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Aldehydes contained in edible oils of a very different nature after prolonged heating at frying temperature: Presence of toxic oxygenated α,β unsaturated aldehydes
Abstract
The evolution of the abundance of the different types of aldehydes, including those that are genotoxic and cytotoxic, oxygenated α,β unsaturated, in the headspace of extra virgin olive, sunflower and virgin linseed oils, submitted to frying temperature for prolonged periods of time, in a discontinuous industrial fryer, was analysed. Very close relationships were found between the abundance of the aldehydes in the three oils at a certain heating time and the original oil composition in the main components. The equations that related these parameters, which can be used for predictive purposes, show not only which acyl group each aldehyde comes from, but also its quantitative influence. This is the first time that the presence of 4-oxo-(E)-2-decenal, and 4-oxo-(E)-2-undecenal have been detected, not only in frying oils, but also in foods. Furthermore, the concentration of aldehydes such as 4-hydroxy-(E)-2-nonenal, (E)-4,5-epoxy-(E)-2-decenal, 4-hydroxy-(E)-2-hexenal, and 4-oxo-(E)-2-nonenal have been determined simultaneously for the first time in these edible oils submitted to frying temperature. The fact that significant concentrations of these toxic compounds were found in some oils before the oil reached 25% of the polar compounds is a cause of concern for human health.
... In the lipid oxidation processes, under very varied conditions, the formation of small molecules by the cleavage of long chain oxidation compounds, is well known. These cleavage compounds can have very varied functional groups such as acid, alcohol, aldehyde, ketone, furanone, epoxide among others [42,[89][90][91], which can be part of small molecules or truncated acyl groups. They can be detected by 1 H NMR if the signals of their protons do not overlap with those of others and if they are in sufficient concentration to be detected by this technique. ...
... These oxylipins are well known oxidation compounds, and have been detected, in previous studies, by gas chromatography as volatile compounds [42,[89][90][91][110][111][112] and by 1 H NMR [37,[113][114][115]. The origin of these oxidation compounds is also in the cleavage of long chain oxidation compounds. ...
... Well known volatile oxidation compounds [42,91] belong to this group of oxylipins. The first two types are formed after molecular rearrangement of others produced in cleavage processes. ...
Sunflower oil samples, both unenriched and enriched with four different concentrations of hydroxytyrosol acetate, were subjected to accelerated storage at 70 °C until a very advanced oxidation stage and the process was monitored by 1H NMR spectroscopy. The aim of the study is to know the effect that the presence of this antioxidant has on the oxidation process of sunflower oil under the aforementioned conditions, as well as on the formation and evolution of the concentration of a significant number of oxylipins. The oxidation process was studied globally by monitoring, during storage time, the degradation of both the linoleic acyl group of sunflower oil, which is the main component of sunflower oil, and the added hydroxytyrosol acetate. Simultaneously, the identification of up to twenty-six different types of oxylipins formed in the oxidation process and the monitoring of the evolution of their concentration over the storage time were carried out. In this way, essential information about the effect that hydroxytyrosol acetate provokes on the oxidation of this oil rich in omega-6 polyunsaturated acyl groups, has been obtained. It has also been shown that the enrichment of sunflower oil with this antioxidant under the conditions tested does not prevent the oxidation process but slows it down, affecting the entire oxidation process.
... The study of several samples through Solid Phase Microextraction followed by Gas Chromatography/Mass Spectrometry (SPME-GC/MS) was carried out, following the same methodology and operating conditions as in previous works [17,34]. The samples, all analyzed in duplicate, were DL, DLVC1-7, DLAsc1-2 and DLAP, obtained in each digestion experiment carried out in triplicate (total n of 6). ...
... Afterward, the fiber containing the extracted components was desorbed for 10 min in the injection port (splitless mode with 5-min purge time) of a 7890 A gas chromatograph equipped with a 5975 C inert mass selective detector MSD with Triple Axis Detector (Agilent Technologies) and a computer operating with the ChemStation program. The column and the operation conditions employed were the same as in previous studies [17,34]. A reference sample of known composition was periodically analyzed in order to verify the extraction efficiency, SPME fiber repeatability and the performance of the equipment. ...
... Among the volatiles coming from linseed oil oxidation during digestion, it can be observed that alkadienals showed the highest abundances in digested samples, followed by alkanals and alkenals, which is in accordance with 1 H NMR data (see Table 3). The main aldehydes detected were reactive 2,4-heptadienals [34,52,53]. Moreover, the oxygenated alpha,beta-unsaturated 4,5-epoxy-2-heptenals and 4,5-epoxy-2-decenals, whose potential toxicity has been described [41,52], were only found in DLAsc1-2 and DLVC1-4. ...
Although widely consumed, dietary supplements based on Vitamin C contain high doses of this compound, whose impact on lipid oxidation during digestion needs to be addressed. Therefore, the effect of seven commercial supplements and of pure l-ascorbic acid and ascorbyl palmitate on linseed oil during in vitro gastrointestinal digestion was tackled. The advance of lipid oxidation was studied through the generation of oxidation compounds, the degradation of polyunsaturated fatty acyl chains and of gamma-tocopherol, by employing Proton Nuclear Magnetic Resonance. Supplements containing exclusively l-ascorbic acid enhanced the advance of linseed oil oxidation during digestion. This was evidenced by increased formation of linolenic-derived conjugated hydroxy-dienes and alkanals and by the generation of conjugated keto-dienes and reactive alpha,beta-unsaturated aldehydes, such as 4,5-epoxy-2-alkenals; moreover, gamma-tocopherol was completely degraded. Conversely, supplements composed of mixtures of ascorbic acid/salt with citric acid and carotenes, and of ascorbyl palmitate, protected linseed oil against oxidation and reduced gamma-tocopherol degradation. The study through Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry of the volatile compounds of the digests corroborated these findings. Furthermore, a decreased lipid bioaccessibility was noticed in the presence of the highest dose of l-ascorbic acid. Both the chemical form of Vitamin C and the presence of other ingredients in dietary supplements have shown to be of great relevance regarding oxidation and hydrolysis reactions occurring during lipid digestion.
... From the early studies in which its usefulness to characterize edible oils and to quantify their unsaturation degree and their molar percentage of the different kinds of acyl groups [35,36] was proved, notable advances have been made in the study of edible oil oxidation processes. These advances refer not only to the evolution of the edible oil oxidation process under different degradative conditions but also to the identification and quantification of new oxidation compounds, many of which are very relevant due to their negative bioactive properties [3][4][5][6][7]9,22,23,32,[37][38][39] Despite these important advances, there are still many unknown aspects related to the complex process of oxidation of edible oils that can be discovered and understood using this technique. ...
... Lipid oxidation is one of the main degradative processes occurring in foods in general and in oil and fats in particular, with serious repercussions for food shelf-life, nutrition, and health. Oils in food processing are submitted to very varied conditions, in both industrial and culinary processes, during which their main and minor components might be degraded [1][2][3][4][5][6][7][8][9][10]. Likewise, some studies have also suggested that during gastrointestinal digestion, oxidation reactions take place, in which lipidic components undergo degradation [11][12][13][14]. ...
... Some of their 1 H NMR signals, whose assignments are given in Table S3, appear at 2.58 (dd), 3.24 (d), 3.98-4.04 (m), 6.05 (dt) and 6.83 (dt) ppm [69]. ...
For the first time, an important number of oxylipins have been identified and quantified in corn oil submitted to mild oxidative conditions at each time of their oxidation process. This oil can be considered as a model system of edible oils rich in polyunsaturated omega-6 groups. The study was carried out using 1H nuclear magnetic resonance spectroscopy (1H NMR), which does not require chemical modification of the sample. These newly detected oxylipins include dihydroperoxy-non-conjugated-dienes, hydroperoxy-epoxy-, hydroxy-epoxy- and keto-epoxy-monoenes as well as E-epoxy-monoenes, some of which have been associated with several diseases. Furthermore, the formation of other functional groups such as poly-formates, poly-hydroxy and poly-ether groups has also been proven. These are responsible for the polymerization and increased viscosity of the oil. Simultaneously, monitoring of the formation of well-known oxylipins, such as hydroperoxy-, hydroxy-, and keto-dienes, and of different kinds of oxygenated-alpha,beta-unsaturated aldehydes such as 4-hydroperoxy-, 4-hydroxy-, 4-oxo-2E-nonenal and 4,5-epoxy-2E-decenal, which are also related to different degenerative diseases, has been carried out. The provided data regarding the compounds identification and their sequence and kinetics of formation constitute valuable information for future studies in which lipid oxidation is involved, both in food and in other scientific fields.
... Lorsque l'huile est chauffée à une température élevée pendant une longue période de temps, des substances toxiques appelées aldéhydes se forment. Les aldéhydes ont été associés à un risque accru de cancer et d'autres maladies ( [90]). Le type d'huile, la température et la durée de cuisson affectent la quantité d'aldéhydes produits. ...
... Le réchauffage de l'huile augmente également la formation d'aldéhyde. Plus la température de chauffage est élevée, plus il y a formation des acides gras atypiques ou des composés néoformés toxiques à l'organisme humain ( [91]; [90]; [92]; [93]). Ceci pourrait engendrer une forte teneur en composés néoformés ou polaires dans les huiles de friture ( [94]). ...
... La chaleur formera entre autre plusieurs composés dans l'huile et les produits frits. Ce qui peut affecter gravement la santé à une certaine dose de composés néoformés comme dont les principaux sont les acides gras trans, les polymères, les monomères cycliques d'acides gras, les hydrocarbures aromatiques polycycliques, l'acrylamide etc ( [91]; [95]; [96]; [92]; [97]; [90]; [98] ; [99]; [93]). [100] et [101] indiquent un risque de mort cardiaque subite, mais aussi de développement de composantes du syndrome métabolique et de diabète suite à une consommation accrue d'acide gras trans. ...
La pandémie de Covid-19 est une pandémie d'une maladie infectieuse émergente, la maladie à coronavirus 2019 (Covid-19), provoquée par le coronavirus SARS-CoV-2. Les pays de l’Afrique subsaharienne affectés par la pandémie sont de plus en plus confrontés à la baisse des matières premières et la chute des échanges internationaux. Les mesures de protection essentielles recommandées par l’OMS (2020) pour limiter la propagation du Coronavirus (Covid-19) caractérisées entre autres par la suppression des déplacements, la quarantaine, le confinement, la fermeture des frontières engendrent une baisse de la productivité des ménages. Les perturbations des termes de l’échange et des chaînes d’approvisionnement agroalimentaire locales affectent déjà la sécurité alimentaire et le bien-être des ménages des pays importateurs de denrées alimentaires. Les prix des aliments augmentent, en particulier les aliments nutritifs. Ne disposant pas encore de traitement universellement accepté contre la Covid-19, il est nécessaire de répertorier les ressources alimentaires capables de booster le système immunitaire de la population vulnérable pour lutter contre le COVID-19 dans un contexte où la sécurité alimentaire est menacée. Le présent document formule des mesures proactives de prévention des risques de malnutrition et de famine liées à la pandémie de Covid-19 et décrit la composition en macronutriments et micronutriments de quelques aliments. Ces mesures sont relatives à une alimentation saine et équilibrée, l’amélioration de l’hygiène alimentaire, l’intensification de la production agricole et agro-alimentaire, l’amélioration des pratiques culinaires et gastronomiques, l’amélioration de la gouvernance de la nutrition et de la sécurité alimentaire dans les pays de l’Afrique Subsaharienne affectés.
Mots clés : Afrique subsaharienne, Covid-19, hygiène, malnutrition, sécurité alimentaire.
... It enables the detection and quantification of certain minor compounds which are present in too low concentrations to be detected by standard pulse experiment. The sample preparation, the acquisition conditions and the study of the spectral data were the same as those used in previous studies (Guillén & Ruiz, 2004;Guillén & Uriarte, 2012;Nieva-Echevarría, Goicoechea, & Guillén, 2019;Ruiz-Aracama et al., 2017). It must be noted that the relaxation delay and acquisition time allow the complete relaxation of the protons, the signal areas thus being proportional to the number of protons that generate them, making it possible to use them for quantitative purposes. ...
... The extraction of the volatile components of the headspace of the samples (0.5 g in 10 mL screw-cap vial) was accomplished automatically using a CombiPAL autosampler (Agilent Technologies, Santa Clara, CA, USA), following the same methodology as in Guillén and Uriarte (2012). The fibre used was coated with Divinylbenzene/ Carboxen/ Polydimethylsiloxane (DVB/CAR/PDMS, 50/30 μm film thickness, 1 cm long), acquired from Supelco (Sigma-Aldrich); this was inserted into the headspace of the sample and maintained for 55 min (50°C), after a pre-equilibration time of 5 min. ...
... follows (Guillén & Uriarte, 2012;Nieva-Echevarría et al., 2017): the oven temperature was set initially at 50°C (5 min hold), increased to 290°C at 4°C/min (2 min hold); the temperatures of the ion source and the quadrupole mass analyser were kept at 230°C and 150°C respectively; helium was used as carrier gas at a pressure of 18.611 psi; injector temperature was held at 250°C; mass spectra were recorded at an ionization energy of 70 eV; and the data acquisition mode employed was Scan (mass spectra range from 40 to 550 m/z). After the first desorption, the fibre was routinely submitted to desorption conditions for a second time to clean up and to determine if the first process was complete. ...
The performance of commercial non-enriched and lycopene-enriched extra-virgin olive oils (EVOO) during in vitro gastrointestinal digestion was studied in order to elucidate potential benefits of lycopene addition. Samples were analyzed before and after digestion by Proton Nuclear Magnetic Resonance (1H NMR) and Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). EVOO samples differed in both main (oleic and linoleic acyl groups) and minor components (phenolic and oxidation compounds). Regardless of the presence of lycopene, all the samples reached a high degree of lipolysis and showed high stability towards oxidation under digestion conditions. Rather than oxidation reactions, the hydroperoxides initially present in the oil were reduced to more stable hydroxides. Likewise, hydroxy-diene isomerization from cis,trans to trans,trans occurred. Hence, the presumed antioxidant effect of lycopene was not noticed during in vitro digestion of EVOO. Similar experiments carried out with a more polyunsaturated oil (sunflower oil) indicated that lycopene slowed down the advance of oxidation slightly. However, in the case of EVOO, its initial quality prevailed over the slight antioxidant effect exerted by lycopene at the concentration present in commercial samples, determining the oxidation compound profile of the digests.
... A wealth of previous reports has demonstrated that, when standardised to frying type, frying vessel size, and frying temperature and duration, the molecular nature and concentrations of aldehydes detectable in culinary oil samples exposed to high-temperature frying practises is critically dependent upon their FA acylglycerol composition, with PUFArich oils such as corn oil engendering much higher levels than MUFA-rich ones (e.g., olive oil), as noted above. Those with only low UFA levels such as coconut oil generate little or no aldehydes, whereas oils with relatively high contents of ω-3 FAs generate patterns of aldehydes which are both MS-and 1 H NMR-distinguishable from those arising from the peroxidation of ω-6 FAs (45)(46)(47)(48)(49). Although this is indeed a generalised conclusion, it is quite correct, and these observations originally made in out laboratory have been largely ratified and validated by those made in many other laboratories globally (46). ...
... One of our group's previous studies (47) (49,50). Indeed, at the extreme 90 min laboratory-simulated shallow frying episode time period, the total mean ± SEM saturated and α,β-unsaturated aldehyde contents of the oils evaluated were 3.56 ± 0.42 and 17.22 ± 0.60 (sunflower oil); 3.13 ± 0.25 and 15.67 ± 0.47 (corn oil); 2.32 ± 0.04 and 11.53 ± 0.14 (canola oil); 2.48 ± 0.09 and 10.62 ± 0.38 (extra-virgin olive oil); and 0.55 ± 0.09 and 4.78 ± 0.80 (MUFArich algae frying oil), respectively. ...
In this manuscript, a series of research reports focused on dietary lipid oxidation products (LOPs), their toxicities and adverse health effects are critically reviewed in order to present a challenge to the mindset supporting, or strongly supporting, the notion that polyunsaturated fatty acid-laden frying oils are “safe” to use for high-temperature frying practises. The generation, physiological fates, and toxicities of less commonly known or documented LOPs, such as epoxy-fatty acids, are also considered. Primarily, an introduction to the sequential autocatalytic peroxidative degradation of unsaturated fatty acids (UFAs) occurring during frying episodes is described, as are the potential adverse health effects posed by the dietary consumption of aldehydic and other LOP toxins formed. In continuance, statistics on the dietary consumption of fried foods by humans are reviewed, with a special consideration of French fries. Subsequently, estimates of human dietary aldehyde intake are critically explored, which unfortunately are limited to acrolein and other lower homologues such as acetaldehyde and formaldehyde. However, a full update on estimates of quantities derived from fried food sources is provided here. Further items reviewed include the biochemical reactivities, metabolism and volatilities of aldehydic LOPs (the latter of which is of critical importance regarding the adverse health effects mediated by the inhalation of cooking/frying oil fumes); their toxicological actions, including sections focussed on governmental health authority tolerable daily intakes, delivery methods and routes employed for assessing such effects in animal model systems, along with problems encountered with the Cramer classification of such toxins. The mutagenicities, genotoxicities, and carcinogenic potential of aldehydes are then reviewed in some detail, and following this the physiological concentrations of aldehydes and their likely dietary sources are considered. Finally, conclusions from this study are drawn, with special reference to requirements for (1) the establishment of tolerable daily intake (TDI) values for a much wider range of aldehydic LOPs, and (2) the performance of future nutritional and epidemiological trials to explore associations between their dietary intake and the incidence and severity of non-communicable chronic diseases (NCDs).
... Some studies have found that a series of chemical changes occur during the high-temperature frying of vegetable oils, which can produce various aliphatic aldehydes as new substances in the oil (Douny et al. 2015;Reed 2011;VanderJagt et al. 1997). Aliphatic aldehydes have attracted considerable research attention as an identification index for waste vegetable oil and due to their link with numerous diseases, such as chronic inflammation, atherogenesis, neurodegenerative diseases, diabetes, and various types of cancer (Guillen and Uriarte 2012;Li et al. 2018;Uriarte and Guillen 2010;Wang et al. 2020;Kristofer and Dennis 2013). The relationship between the formation of aliphatic aldehydes in vegetable oils and high-temperature frying has not been reported, and the mechanism of the formation of aliphatic aldehydes in different vegetable oils remains to be revealed. ...
... First, the changes in aliphatic aldehydes in olive oil with different frying durations were investigated at 165 ± 1 °C, with the results shown in Fig. 3A and Table S3. It is generally believed that the content of aliphatic aldehydes in vegetable oils increases with increased frying time (Guillen and Uriarte 2012;Li et al. 2018). Compared with fresh olive oil, the content of aliphatic aldehydes formaldehyde, n-hexanal, n-heptaldehyde, n-octanal, and n-nonyl aldehyde increased markedly after frying. ...
The type and content of fatty aldehydes is an important index to evaluate the quality of vegetable oil. In this paper, the formation of aliphatic aldehydes in four vegetable oils was investigated by simulating different frying temperatures and durations. The generated aliphatic aldehydes were analyzed by optimizing HPLC–MS/MS detection conditions using 2,4-dinitrobenzene hydrazine as the derivatizing reagent and p-toluenesulfonic acid as the catalyst. The linearity, detection limit recovery, and repeatability of the method were investigated. The detection results showed that the content of aliphatic aldehyde increased by dozens of times during the high-temperature frying process compared with fresh vegetable oils. This method identified differences in the formation of aliphatic aldehydes in vegetable oils and provides an option to identify waste vegetable oils by evaluating the changes in aliphatic aldehyde content.
... During oil frying processes, several compounds (nonvolatile and volatile) are generated as secondary products, and aldehydes are considered oil quality indicators because of the degraded odor generated by its presence (ben Hammouda et al. 2017;Cao et al. 2014;Guillén and Uriarte 2012;Katragadda et al. 2010). Therefore, in this study, pentanal, hexanal, heptanal, and nonanal were determined by HPLC-DAD in the palm olein, soya bean oil, and sunflower oil. ...
... The chromatograms (Fig. S2) indicate that different carbonyl compounds were obtained; however, pentanal and hexanal are the aldehydes that could be identified in the three oils. These aldehydes were identified in edible vegetable oil evaluations described by Guillén and Uriarte (2012), Peng et al. (2017), and Seppanen and Csallany (2001). For this reason, these compounds were used to evaluate the electrochemical conditions. ...
One of the main concerns about the use of edible vegetable oils in food industry frying processes is the oxidative degradation due to the high temperatures, presence of oxygen, ultraviolet radiation, and the presence of metal ions. The main compounds formed during oxidative reactions include aldehydes, ketones, alcohols, and carboxylic acids, being some of these electroactive compounds, which can be used with quantification purposes. In this work, cyclic voltammetry and a flow method based on headspace sampling with amperometric detection were performed, followed by principal component and cluster analysis to classify palm olein, soya bean, and sunflower oil samples according to their degradation state. The electrochemical techniques were based on the use of 1-butyl-3-methylimidazolium hexafluorophosphate as conductive media. The amperometric profile information provided a clearer classification than the voltammetric profile. Additionally, the amperometric results were applied to determine iodine value and aldehyde content by means of a partial least square regression. The values obtained were statistically similar than the estimated using 1H nuclear magnetic resonance spectroscopy and HPLC. The combination of electrochemical techniques and chemometric analysis offers valuable information for classification and quantification purposes.
... Hence, to date, high-resolution NMR analysis has been proven to provide a highly valuable, virtually non-destructive high-throughput analytical technique for monitoring the molecular nature and levels of many major acylglycerol FA species, along with a wide range of minor lipid-soluble agents such as chain-breaking antioxidants, phytosterols, terpenes and chlorophylls, in edible oil samples [12,21,47,49]. Of especial benefit are the applications of this analytical strategy to determine a series of sequentially generated LOPs, e.g., CHPDs and HPMs, along with a range of aldehydic and further fragmentation products, present in unused or used CFOs [12,20,50]. ...
... Certainly, a large number of the aldehydes generated are volatilised at standard frying temperatures, and this may also present serious health hazards in view of their inhalation by humans, especially those working in fast-food retail outlets or restaurants with insufficient or inadequate ventilation precautions, or those performing classical Chinese-style wok cooking episodes domestically. This is especially the case for aldehydes arising from the peroxidation of linoleoyl-and linolenoyglycerols (particularly deca-trans,trans-2,4-dienal and acrolein, respectively), since the great majority of aldehydic secondary LOPs generated therefrom have boiling-points (b.pts) <180 • C [49], at least some of them substantially so. ...
Continuous or frequent ingestion of fried foods containing cytotoxic/mutagenic/genotoxic lipid oxidation products (LOPs) may present significant human health risks; such toxins are generated in thermally stressed polyunsaturated fatty acid (PUFA)-rich culinary frying oils (CFOs) during standard frying practices. Since monounsaturated and saturated fatty acids (MUFAs and SFAs, respectively) are much less susceptible to peroxidation than PUFAs, in this study CFOs of differential unsaturated fatty acid contents were exposed to laboratory-simulated shallow-frying episodes (LSSFEs). Firstly, we present a case study exploring the time-dependent generation of aldehydic LOPs in CFO products undergoing LSSFEs, which was then used to evaluate the relative potential health risks posed by them, and also to provide suitable recommendations concerning their safety when used for frying purposes. Sunflower, rapeseed, extra-virgin olive and coconut oils underwent LSSFEs at 180 °C: Samples were collected at 0–90 min time-points (n = 6 replicates per oil). Aldehydes therein were determined by high-resolution 1H NMR analysis at 400 and 600 MHz operating frequencies. For one of the first times, CFO LOP analysis was also performed on a non-stationary 60 MHz benchtop NMR spectrometer. 1H NMR analysis confirmed the thermally promoted, time-dependent production of a wide range of aldehydic LOPs in CFOs. As expected, the highest levels of these toxins were produced in PUFA-rich sunflower oil, with lower concentrations formed in MUFA-rich canola and extra-virgin olive oils; in view of its very high SFA content, only very low levels of selected aldehyde classes were generated in coconut oil during LSSFEs. Secondly, 1H NMR results acquired are discussed with regard to the suitability and validity of alternative, albeit routinely employed, spectrophotometric methods for evaluating the peroxidation status of CFOs and lipid-containing foods. Thirdly, an updated mini-review of the toxicological properties of and intake limits for LOPs, and deleterious health effects posed by their ingestion, is provided. In conclusion, exposure of PUFA-rich CFOs to high-temperature frying practices generates very high concentrations of aldehydic LOP toxins from thermally promoted, O2-powered, recycling peroxidation processes; these toxins penetrate into and hence are ‘carried’ by fried foods available for human consumption. Such toxins have the capacity to contribute towards the development and progression of non-communicable chronic diseases (NCDs) if cumulatively ingested by humans.
... Among the aldehydes that increased continuously at 185°C (cluster B in Figure 5m), 2-undecenal (X), 2-decenal (IX), and octanal (V) mainly originate from the hemolytic β-scission of 8-, 9-, and 11-hydroperoxides of oleic acid, respectively (Cao et al., 2020;Ho & Chen, 1994), while 2-nonenal (VI) might from further decomposition of 2-undecenal (Warner et al., 2001). Among the aldehydes that peaked within 2 hr of 185°C heating in VOO (cluster A in Figure 5m), 2,4-decadienal (VIII) and 2-octenal (IV) are the known breakdown products of linoleic acid and trilinolein (Choe & Min, 2006;Warner et al., 2001) while 2,4-heptadienal (II) is the oxidation products of α-linolenic acid (Guillén & Uriarte, 2012;Ho & Chen, 1994). Interestingly, nonanal (VII) has been shown as a degradation product from oleic acid (Cao et al., 2020;Guillén & Uriarte, 2012), but its formation pattern was more comparable to the aldehydes degraded from linoleic acid, such as 2,4-decadienal (VIII) and 2-octenal (IV), than the ones from oleic acid. ...
... Among the aldehydes that peaked within 2 hr of 185°C heating in VOO (cluster A in Figure 5m), 2,4-decadienal (VIII) and 2-octenal (IV) are the known breakdown products of linoleic acid and trilinolein (Choe & Min, 2006;Warner et al., 2001) while 2,4-heptadienal (II) is the oxidation products of α-linolenic acid (Guillén & Uriarte, 2012;Ho & Chen, 1994). Interestingly, nonanal (VII) has been shown as a degradation product from oleic acid (Cao et al., 2020;Guillén & Uriarte, 2012), but its formation pattern was more comparable to the aldehydes degraded from linoleic acid, such as 2,4-decadienal (VIII) and 2-octenal (IV), than the ones from oleic acid. The association between aldehyde formation and fatty acid composition is also supported by our study on the aldehyde formation in soybean oil (Wang, Csallany, et al., 2016). ...
Camellia oil is widely recognized as a high‐quality culinary oil in East Asia for its organoleptic and health‐promoting properties, but its chemical composition and thermal stability have not been comprehensively defined by comparisons with other oils. In this study, the triacylglycerols (TAGs) in camellia, olive, and six other edible oils were profiled by the liquid chromatography‐mass spectrometry (LC‐MS)‐based chemometric analysis. Besides observing the similarity between camellia oil and olive oil, TAG profiling showed that OOO, POO, and OOG (O: oleic acid, P: palmitic acid, and G: gadoleic acid) can jointly serve as the identity markers of camellia oil. Thermal stability of virgin camellia oil (VCO) was further evaluated by extensive comparisons with virgin olive oil (VOO) in common lipid oxidation indicators, aldehyde production, and antioxidant and pro‐oxidant contents. The results showed that p‐anisidine value (AnV) was the sensitive lipid oxidation indicator, and C9‐C11 aldehydes, including nonanal, 2‐decenal, 2,4‐decadienal, and 2‐undecenal, were the most abundant aldehydes in heated VCO and VOO. Under the frying temperature, heated VCO had lower AnV and less aldehydes than heated VOO. Interestedly, the VCO had lower levels of pro‐oxidant components, including α‐linolenic acid, free fatty acids, and transition metals, as well as lower levels of antioxidants, including α‐tocopherol and phenolics, than the VOO. Overall, great similarities and subtle differences in TAG and aldehyde profiles were observed between camellia and olive oils, and the thermal stability of camellia oil might be more dependent on the balance among its unsaturation level, pro‐oxidant, and antioxidant components than a single factor.
... The boiling points of various aldehydes in three edible oils have been evaluated previously [35]. In the current study, the boiling points of individual aldehydes largely match their distribution profile in five OSOs ( ...
... However, hexanal has much lower cytotoxicity than 2,4-decadienal and 4-HNE [69,70], and is not an ideal prediction marker of animal performance. As for 4-HNE and 2,4-decadienal, 4-HNE is one of the most cytotoxic secondary LOP [9,12], while 2,4-decadienal was commonly detected as the most abundant aldehyde in the thermally-oxidized vegetable oils rich in linoleic acid [31,35,71]. Therefore, their robust inverse correlations with ADG were not surprising. ...
Abstract Background The benefits of using the oxidized oils from rendering and recycling as an economic source of lipids and energy in animal feed always coexist with the concerns that diverse degradation products in these oxidized oils can negatively affect animal health and performance. Therefore, the quality markers that predict growth performance could be useful when feeding oxidized oils to non-ruminants. However, the correlations between growth performance and chemical profiles of oxidized oils have not been well examined. In this study, six thermally oxidized soybean oils (OSOs) with a wide range of quality measures were prepared under different processing temperatures and processing durations, including 45 °C-336 h; 67.5 °C-168 h; 90 °C-84 h; 135 °C-42 h; 180 °C-21 h; and 225 °C-10.5 h. Broilers and nursery pigs were randomly assigned to diets containing either unheated control soybean oil or one of six OSOs. Animal performance was determined by measuring body weight gain, feed intake, and gain to feed ratio. The chemical profiles of OSOs were first evaluated by common indicative tests, including peroxide value, thiobarbituric acid reactive substances, p-anisidine value, free fatty acids, oxidized fatty acids, unsaponifiable matter, insoluble impurities, and moisture, and then analyzed by the liquid chromatography-mass spectrometry-based chemometric analysis. Results Among common quality indicators, p-anisidine value (AnV), which reflects the level of carbonyl compounds, had the greatest inverse correlation with the growth performance of both broilers and pigs, followed by free fatty acids and oxidized fatty acids. Among the 17 aldehydes identified in OSOs, C9-C11 alkenals, especially 2-decenal and 2-undecenal, had stronger inverse correlations (r
... It is known, however, that oils degrade while heating, especially when the heating temperatures are high and the time exposed to these temperatures is long. 1 The safety of oils subjected to heating at frying temperatures and the influence of volatile and semi-volatile compounds formed such as aldehydes and polycyclic aromatic hydrocarbons (PAHs), which are considered the most abundant toxic and carcinogenic compounds in frying oil, because it can be ingested either directly from degraded oil or through used frying oil, in addition to alkyl-and alkenyl-benzene derivatives occurrence, had gained great attention by researchers. 2,3 To prevent frying in unsafe oil or fried food, there are many countries and organizations that have established maximum residue limit values MRL for PAHs in edible oil. ...
... [9][10][11] Recently, many studies have addressed the presence of a,b-unsaturated aldehydes in different types of food: French fries, extra virgin olive, sunflower, and virgin linseed oils. 1,3,6,[8][9][10]12 Saral et al. in 2019 studied a total of a,b-unsaturated aldehydes in different types of culinary oils such as Extra-virgin oil, sunflower, and corn at 20 and 90 minutes, in which the total concentrations were found between 0.51-3.9 and 4.78-17.72 ...
In this study, an efficient gas chromatography with mass-spectrometric detector (GC/MS) method has been developed for extraction and quantita-tion of 16 carcinogenic polycyclic aromatic hydrocarbons PAH in frying edible oil. The method showed satisfactory linearity (R 2 > 0.995) over the range (1.00-100.0 mg kg À1), the limits of detection were 0.0700 to 1.26 mg kg À1 , limits of quantitation ranged from 0.230 to 4.20 mg kg À1 , and the recovery ranged from 71.5% to 101. %. Samples of used frying edible oils have been collected from different fast food restaurants in Jordan. The mean of the 16 PAH in the oil samples ranged from 1.49 to 65.7 mg kg À1 , while the concentration of Benzo[a]pyrene ranged from 3.08 to 4.09 mg kg À1. In addition, the incremental lifetime cancer risk (ILCR) associated with PAH was estimated, and ranged from 1.01 Â 10 À9 to 3.33 Â 10 À6 , indicating a slight potential risk. A second objective of this research involved calculation of p-Anisidine values (AVs) in the collected frying oil samples as an indicator for the presence of a,b-unsaturated aldehydes. The AVs in the investigated oil samples ranged from 14.3 to 71.3 and the estimated concentration of a,b-unsaturated aldehydes was 33 lmol g À1 which is higher that the internationally proposed maximum limits. The outcomes of this study show that regulations on PAHs and a,b-unsaturated aldehydes in frying oils must be established in Jordan. ARTICLE HISTORY
... In recent years, many studies have found that most complex chemical reactions in the frying process lead to the degradation of oil, which affects the safety of fried food. In addition, the degradation of oil can easily produce many toxic and harmful compounds such as aldehydes, ketones, and trans fatty acids, which are harmful to human health [13][14][15][16]. A previous report showed that a large amount of (E,E)-2,4-decadienal produced after frying produces a pleasant deep-fried flavor, while the formation of hexanoic acid, heptanic acid, octanoic acid, and nonanoic acid is related to an unpleasant rancidity flavor [17]. ...
Fragrant rapeseed oil (FRO) is a frying oil widely loved by consumers, but its quality deteriorates with increasing frying time. In this study, the effect of high-canolol phenolic extracts (HCP) on the physicochemical properties and flavor of FRO during frying was investigated. During frying, HCP significantly inhibited the increase in peroxide, acid, p-anisidine, and carbonyl values, as well as total polar compounds and degradation of unsaturated fatty acids. A total of 16 volatile flavor compounds that significantly contributed to the overall flavor of FRO were identified. HCP was effective in reducing the generation of off-flavors (hexanoic acid, nonanoic acid, etc.) and increased the level of pleasant deep-fried flavors (such as (E,E)-2,4-decadienal). Therefore, the application of HCP has a positive effect on protecting the quality and prolonging the usability of FRO.
... Since the α-amino group of lysine is the target group of saturated aldehydes and the thiol group of cysteine is the target group of unsaturated aldehydes in proteins, if these susceptible amino acids are involved in protein function, aldehyde modification will lead to the inactivation of the protein, thereby exerting cytotoxic effects 20 . Unsaturated aldehydes are more dangerous because they are more lipophilic and can destroy biofilms with the intake of oils into the body 21 . α,β oxidized unsaturated aldehydes are a kind of free aldehydes produced by the degradation of hydroperoxides of unsaturated fatty acids 22 , which are active in nature, of which 4-hydroxy-2-trans-nonenal HNE is suspected to be associated with atherosclerosis, liver disease, Parkinson s disease, Alzheimer s disease, and Huntington s syndrome 23 . ...
Thermal processing, a common processing method of vegetable oil in daily life, is accompanied by the formation of some harmful substances. This study determined the peroxide value, anisidine value, total peroxide value, polar compound content, fatty acid content, and core aldehyde content of hazelnut oil under different thermal processing conditions. The oxidation kinetics equation of fatty acid and temperature of hazelnut oil was established, and the correlation between the contents of fatty acid and core aldehyde and four oxidation indexes was analyzed. The results showed that the TPC of hazelnut oil exceeds 24% when heated for 10 min at 210ºC, indicating that hazelnut oil is not suitable for high temperature and long-time heating. The contents of linoleic acid and oleic acid in hazelnut oil varied significantly at different thermal processing temperatures (p ≤ 0.01). The change of linoleic acid was more consistent with the first-order oxidation kinetics model. Two core aldehydes were detected in hazelnut oil, aldehyde 9-oxo and aldehyde 10- oxo-8. The core aldehyde 9-oxo content changed most obviously with the heating temperature, and it was the main non-volatile aldehydes of hazelnut oil thermal oxidation. Correlation analysis showed that the heating temperature of hazelnut oil had a significant effect on the oxidation index (p ≤ 0.01), and linoleic acid had the strongest correlation with the oxidation index, which could reflect the overall oxidation of hazelnut oil. The total amount of core aldehyde and the content of core aldehyde 9-oxo strongly correlated with the oxidation index (p ≤ 0.01), which can be used as one of the indicators to evaluate the oxidation degree of hazelnut oil. This study is of great significance for promoting the application of hazelnut oil in daily cooking and processing.
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... Dominguez et al. (6) replaced 100% of the fat with olive oil in pork pate, which considerably increased the level of MUFAs and tocopherol in the final product without changing the physicochemical characteristics. The use of fish oil, olive oil, and a combination of olive and fish oil to replace 25-75% of the pork fat drastically increased the PUFAs content in Spanish salchichon and frankfurter sausages (7,8). ...
Fatty acid profile, protein and fatty acid oxidation and flavor profile of pan-fried chicken patties formulated with various levels of Perilla frutescens seed meal (PSM) as a fat substitute was investigated in this study. The formation of heterocyclic amines (HCAs) in the chicken patties was also evaluated. The results showed that pan-fried patties formulated with 20% PSM (PSM4) had the highest ranges of oleic acid and ΣMUFA content and ΣPUFA/ΣSFA ratio. Low to medium levels of PSM (PSM1, 2, and 3 corresponding to 5, 10, and 15% of PSM, respectively) reduced the content of lipid peroxidation products, while high level (PSM4) increased it. All levels of PSM were also found to be effective against elevation in carbonyl content relative to the control. Moreover, the PSM effectively inhibited HCA formation in the chicken patties. The total contents of HCAs in PSM1, PSM2, PSM3, and PSM4 samples were significantly (P < 0.05) lower than that of the control sample, corresponding to 31.9, 46.1, 57.2, and 44.8% inhibition, respectively. PSM4, however, had no or very little effect on the formation of PhIP, 4,8-DiMeIQx and AαC, despite a strong inhibitory effect on MeIQx formation. These findings not only support the promising potential of PSM for application as a fat substitute to improve the fatty acid profile and reduce the content of harmful by-products in heat-processed chicken, but also highlight that appropriate addition level is a critical factor in optimizing the functional capacity of this natural agent.
... The generated aldehydes could impart undesirable flavors to the oil, such as oily, green, paint, metallic, and beany [5], which in turn affect the oil quality. Consequently, there is a growing body of literature that recognizes the importance of aldehydes in frying oil [6][7][8]. ...
To establish a practical model for evaluating the oxidation of frying oil using aldehydes, the aldehydes of 10 commercial oils during frying at 180 °C were identified using headspace-gas chromatography/mass spectrometry, and the changes of common aldehydes and their correlation with carbonyl values (CV) were analyzed. The results showed that the total peak area of aldehydes increased significantly with heating time, which was related to the fatty acid and tocopherol contents of the oils. There were four common aldehydes with different trends during frying, namely, pentanal, hexanal, (E)-hept-2-enal, and nonanal. Moreover, pentanal with a high correlation with CV was selected as the quality evaluating index of frying oil due to its stable accumulation over time. Based on the linear fitting relationships between CV and pentanal, as well as the initial content ratio of linoleic acid to palmitic acid and total tocopherols in oils, a predictive model was established for evaluating the quality of frying oils with high precision and non-reagent by using mass spectrometry. In summary, this work provides theoretical support for using aldehyde as the quality evaluation index of frying oil and provides a new idea for evaluating oil deterioration from the perspective of volatile compounds.
... As mentioned earlier, the aldehyde is a secondary lipid oxidation product from the degradation of fatty acids in oil via hydroperoxide. Guillen and Uriarte (2012) reported that the non-volatile aldehydes remained in the oil during the (a) deep-frying process, hence, they can be found in fried foods. ...
Palm olein oil is widely used as a medium for deep-frying purposes in the domestic and commercial sectors. However, repetitive usage beyond the recommended cycle leads to significant deterioration and spoilage of the oil. Therefore, this research investigated the effect of long-term repetitive deep-fat frying on the physicochemical properties of Refined, Bleached and Deodorised Malaysian Tenera Palm Olein oil (RBDPO) as well as the suitability of poly(L-lactic acid) (PLLA) film as a potential rapid indicator to determine the spoilage level of recycled palm olein oil. The study was carried out using three different RBDPO conditions; RBDPO without potatoes (RBDPO-1), RBDPO with potatoes (RBDPO-2), and RBDPO with Afdhal Oil (AO, an oil additive chemical) and potatoes (RBDPO-3). The deep-frying process was performed for 15 mins at 180 ± 5 °C for 15 cycles. Based on the results, the oil temperature fluctuation during the frying process was insignificant for every cycle (p > 0.05). After 15 frying cycles, all oil samples demonstrated a considerably altered and deteriorated composition, both physically and chemically. The comparison between the 1st and 15th frying cycles showed a significant difference (p 0.05) between the 1st and 15th frying cycles for all types of oil. Besides, the peroxides value (PV) was steadily increased within the safety limit of Food Act (1983) (Laws of Malaysia: Act 281), with the aldehyde (CO) functional group was detected in all oil samples throughout the 15 frying cycles. Hence, the high correlation between the contact angle and all parameters except density showed that contact angle analysis using PLLA film was a suitable technique for rapid oil spoilage indicator model.
... Frying is a popular cooking method, which causes deterioration of oil quality and formation of toxic oxidation products (Guillén & Uriarte, 2012). Vegetable oils containing high levels of unsaturated fatty acids have many health benefits, yet they are prone to oxidation due to those unsaturated fatty acids (Choe & Min, 2006). ...
Previous studies reported that several amino acids had strong antioxidant activity in vegetable oils under frying conditions. In this study, the carboxylic acid group of amino acids was converted to a carboxylate group (-COO-Na+ or -COO-K+), a heating study was conducted with amino acid salts in soybean oil at 180 ºC. Sodium salts of amino acids including alanine, phenylalanine, and proline and disodium glutamate had significantly stronger antioxidant activity than the corresponding amino acids, and potassium salts had stronger antioxidant activity than sodium salts. Potassium salts of alanine and phenylalanine more effectively retained tocopherols in soybean oil than the corresponding amino acids during heating. Phenylalanine potassium salt had stronger antioxidant activity than phenylalanine in other vegetable oils including olive, high oleic soybean, canola, avocado, and corn oils. Phenylalanine potassium salt at 5.5. mM more effectively prevented oil oxidation than tert-butyl hydroquinone (TBHQ), a synthetic antioxidant, at its legal concentration limit (0.02%) indicating its feasibility as a new antioxidant for frying.
... Cooking oils also contain a remarkable 32 aliphatic aldehydes (alkanals, alkenals, and diand trienals), some of which are toxic. Essential oils used for their antimicrobial activities in medicine, agriculture, and food preservation also contain a range of aldehydes, including cinnamaldehyde, citral, 4-anisaldehyde, vanillin, hexenal, hexanal, and cuminaldehyde (51,52). Hence, aldehydes from digested foods as well as antimicrobials are potentially toxic to healthy gut microbes. ...
Significance
The diverse microorganisms contained within the human gut are known to have significant effects on human health. Herein, we show that genes encoding members of the tungsten oxidoreductase (WOR) family of enzymes and a tungstate-specific transporter are prevalent in the human gut microbiome and metagenome. We demonstrate that two model gut microbes assimilate tungsten into multiple WOR enzymes and that some of these enzymes catalyze the conversion of gut aldehydes to the corresponding acid, likely as a detoxification strategy to remove these reactive compounds.
... Similar results were also reported by authors. 84,85 3.6.3 | Catalytic tests Table 5 presents the results of the experimental planning developed to optimize the input variables in the simultaneous esterification and transesterification reactions, where the catalytic tests with Ni 0.5 Zn 0.5 Fe 2 O 4 MNPs were conducted using waste frying oil samples. ...
Different types of waste oils (soybean, sunflower, corn, and cottonseed) were evaluated in simultaneous esterification and transesterification reactions for more sustainable production of biodiesel by heterogeneous magnetic catalysis. The Ni0.5Zn0.5Fe2O4 magnetic nanoparticles (MNPs) were synthesized by combustion reaction on a pilot‐scale of 200 g/batch, showing obvious conditions for possible scalability for large scale production. The properties of the MNPs were investigated by X‐ray diffraction, Rietveld refinement, UV‐Vis, Brunauer, Emmett, and Teller/Barrett, Joyner, and Halenda method, granulometric distribution, pH, zeta potential, and NH3‐TPD. The results confirmed the formation of the majority phase of the inverse NiZn spinel, with median particle of 39.6 nm, and surface area of 64 m²/g with acid character. The quality measures provide the adequacy of the biodiesel obtained and the gas chromatography showed conversions from 86.65% to 98.12%. Finally, the MNPs were successfully recovered and reused in three more cycles without activity loss, and with capacity for new recycles due to its high reactivity and stability.
... The volatile aldehydes in fish oil were determined according to previous studies. 10,16 Briefly, 3 mL of 17 mg/mL PFBHA solution in methanol was put into 15 mL amber Teflon-capped vials with a 1 cm stirring bar. A solid-phase microextraction (SPME) fiber coated with PDMS/DVB (65 μm) was placed in the headspace of the vial for 5 min to adsorb the volatile PFBHA. ...
In this research, we studied the antioxidative properties and chemical changes of quercetin in fish oil during accelerated storage at 60 °C for 5 days. Gas chromatography (GC) analysis showed that quercetin inhibited aldehyde formation and unsaturated fatty acid oxidation in fish oil significantly; however, the inhibitory effects decreased gradually with prolonged heating time. Moreover, quercetin was consumed with increasing heating time. Some new phenolic derivatives were discovered in the fish oil with quercetin, with their structures fully elucidated by LC-MS/MS and comparison with newly synthesized ones (characterized by MS and NMR spectroscopy). Based on their chemical structures, we proposed that quercetin reacted with EPA and DHA to form the corresponding quercetin fatty acid esters in fish oil. In addition, the newly formed quercetin-3-O-eicosapentaenoate and quercetin-3-O-docosahexaenoate showed weaker DPPH and ABTS radical cation scavenging activity but much improved lipophilicity, higher cell membrane affinity, and hence enhanced cellular antioxidant activity compared with the parent quercetin. Overall, quercetin could be used as a safe dietary polyphenol to inhibit lipid oxidation. The newly formed quercetin-polyunsaturated fatty acid esters may render improved bioactivity to humans, which needs further investigation.
... Les réactions thermiques des corps gras, en absence d'oxygène sont à l'origine de la formation de nombreuses substances [76] : ...
Le projet de recherche appliquée portait sur la valorisation des huiles de friture usagées en tant que biolubrifiant pour chaîne de tronçonneuse. Ces huiles collectées dans les différentes enseignes de restauration présentent une teneur élevée en composés polaires, une acidité élevée, une grande variabilité dans leur composition en acides gras, relatives aux différentes marques d'huiles végétales utilisées. Ces mélanges d'huiles végétales (colza, tournesol, arachide, palme, coprah), déjà valorisés dans la filière des biocarburants, présentent des propriétés physico-chimiques intéressantes (indice de viscosité, biodégradabilité, composition en acides gras) qui leur permettraient de concurrencer les lubrifiants d'origine minérale ou végétale que l'on trouve sur le marché, notamment dans le secteur forestier. Un procédé d'ultrafiltration par membrane céramique a permis de réduire la teneur en composés polaires ainsi que l'acidité consécutive au procédé de friture profonde, tout en réduisant le phénomène de colmatage. L'utilisation de la méthodologie des surfaces de réponse a contribué à optimiser les paramètres de température, pression, porosité des membranes, afin d'améliorer les débits de filtration. La formulation de ce biolubrifiant à partir du mélange d'huiles obtenu, optimisé par plan de mélanges, a conduit à l'obtention d'un produit de grade ISO 150 dont les caractéristiques «filant», «adhésivité » et « point d'écoulement » répondent au cahier des charges. Une étude de biodégradabilité selon la norme OCDE 301B a montré que l'huile formulée est biodégradable à 90%, faiblement toxique selon les tests OCDE 201, 202, 203, et ne présente pas d'allergénicité
... Todos estos aldehídos son muy reactivos y pueden interaccionar con proteínas, hormonas, enzimas y otros componentes del organismo, modificando su estructura y en ocasiones su función (1) . ...
El objetivo del presente estudio fue evaluar el efecto hepatoprotector del gel de Aloe vera modificado (GAVM) frente a la injuria inducida en ratones albinos por la administración, vía oral, de aceite comestible recalentado (ACR) mezclado con dimetilsulfóxido (DMSO) (1:1). Las dosis de ACR usadas fueron 2,3 y 3,1 mL/kg, administradas por 14 días, lo cual produjo incremento de las transaminasas (ALT, AST) y triglicéridos. A los ejemplares que recibieron la menor dosis de ACR (2,3 mL/kg de peso), a partir del día 14 y por 18 días, se les suministró, adicionalmente, cuatro gotas diarias de GAVM equivalente a 6,1 mL/kg de peso. Al analizar los resultados obtenidos a los 14, 19, 28 y 33 días de iniciado el tratamiento, se observó disminución progresiva significativa de ALT, AST y triglicéridos. Sin embargo, los ejemplares que recibieron mayor dosis de ACR (3,1 mL/kg de peso) más GAVM, presentaron incremento en los niveles de ALT, AST y triglicéridos conforme transcurrió el tiempo, sugiriendo que la peroxidación lipídica y los radicales libres formados rebasan el efecto hepatoprotector del GAVM. Los niveles de proteínas no experimentaron variaciones significativas. Los ratones de tres grupos control no presentaron variaciones significativas en los indicadores bioquímicos estudiados, sin embargo, en el grupo control que recibió GAVM se observó disminución de triglicéridos. En conclusión, el GAVM mostró efecto hepatoprotector ante una dosis 2,3 mL/kg de peso de ACR, no sucediendo lo mismo al aumentar el ACR (3,1 mL/kg de peso), ante lo cual la dosis de GAVM fue insuficiente.
... This waste cooking oil may be carcinogenic. Scientists have found that, repeated use of waste cooking oil is dangerous for health, because it releases toxic aldehydes and alylbenzenes (1,2), which may be linked to serious illnesses like cardiac problems, dementia and cancer. Keeping the large population of India in mind, dumping of waste cooking oil may enforce severe ecological issues. ...
Brazil is using bio-diesel as an alternate fuel to run cars. Rapid growth of bio-fuels all around the world is mainly due to energy crisis and ecological concerns, and in this dynamic market mechanisms, lot of efforts are being made to facilitate the growth of bio-fuels. In India, the main Goal of the Biofuel Policy is to make sure that, a bare
minimum level of bio-fuels turns out to be readily accessible in the marketplace, to meet up the requirement at any given time. A pinpointing objective of 20% blending of bio-fuels, by 2017 was to be achieved, but still we are far behind. Even though raw vegetable oils can also be used in compression ignition engines, however, their high viscosities, poor flow properties in cold and low volatilities have made them unsuitable. Consequently, we need to investigate various other
derivatives. In this research, Biodiesel was prepared by the process of trans-esterification, from waste cooking refined soyabean oil. Thereafter, an experimental investigation was carried out on a 4-stroke Compression ignition engine, with single cylinder which is fueled with blends of Biodiesel and petro diesel. 6 blends of biodiesel were taken for investigating performance characteristics of engine, under different conditions of load. Blend B20 of biodiesel was found most suitable among all blends of biodiesel and petro diesel
Keywords: Biodiesel, Performance, Diesel Engine & Waste Cooking Oil
... Trans, trans-2,4-decadienal (tt-DDE) is a highly reactive α,β-unsaturated aldehyde. It is not only a food additive/flavoring agent, a major byproduct of polyunsaturated lipid oxidation during storage and heating [21] but also an endogenously generated product of oxidative stress-mediated lipid peroxidation of cell membranes [22]. Dietary tt-DDE was reported to be absorbed and distributed to multiple organs and tissues, promoting enlargement of atherosclerotic lesions [23]. ...
Aldehydes are implicated in the development of hypertension. Trans, trans-2,4-decadienal (tt-DDE), a dietary α,β-unsaturated aldehyde, is widespread in many food products. However, the role of tt-DDE in the pathophysiology of hypertension remains unknown. This study was designed to investigate whether tt-DDE consumption evokes hypertension and to explore the mechanisms underlying such a role. Sprague-Dawley rats were administered different concentrations of tt-DDE. After 28 days, blood pressure and endothelial function of mesenteric arteries were measured. Results showed that tt-DDE treatment significantly increased blood pressure and impaired endothelial function based on endothelium-dependent vasorelaxation and p-VASP levels. Mechanistically, tt-DDE induced oxidative/nitrative stress in the arteries of rats as evidenced by overproductions of superoxide and peroxynitrite, accompanied with increased expressions of iNOS and gp91phox. To further investigate the effects of tt-DDE on endothelial cells and underlying mechanisms, human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of tt-DDE. tt-DDE induced oxidative/nitrative stress in HUVECs. Moreover, tt-DDE induced endothelial cells apoptosis through JNK-mediated signaling pathway. These results show, for the first time, that oral intake of tt-DDE elevates blood pressure and induces endothelial dysfunction in rats through oxidative/nitrative stress and JNK-mediated apoptosis signaling, indicating that excess ingestion of tt-DDE is a potential risk factor for endothelial dysfunction and hypertension.
... Food lipid oxidation is an issue of great importance in field of the food technology because it causes food degradation with economic and health repercussions. This can occur during food processing and storage [1,2]. A common strategy to avoid oxidation consists of the incorporation of compounds with antioxidant abilities in foods. ...
The effect of enriching virgin flaxseed oil with dodecyl gallate, hydroxytyrosol acetate or gamma-tocopherol on its in vitro digestion is studied by means of proton nuclear magnetic resonance and solid phase microextraction followed by gas chromatography/mass spectrometry. The extent and pattern of the lipolysis reached in each sample is analyzed, as is the bioaccessibility of the main oil components. None of the phenolic compounds provokes inhibition of the lipase activity and all of them reduce the lipid oxidation degree caused by the in vitro digestion and the bioaccessibility of oxidation compounds. The antioxidant efficiency of the three tested phenols is in line with the number of phenolic groups in its molecule, and is dose-dependent. The concentration of some minor oil components such as terpenes, sesquiterpenes, cycloartenol and 24-methylenecycloartenol is not modified by in vitro digestion. Contrarily, gamma-tocopherol shows very low in vitro bioaccessibility, probably due to its antioxidant behavior, although this increases with enrichment of the phenolic compounds. Oxidation is produced during in vitro digestion even in the presence of a high concentration of gamma-tocopherol, which remains bioaccessible after digestion in the enriched samples of this compound.
... [1][2][3] . However, during long-term storage or the deep-frying process, vegetable oils are prone to complex chemical reactions such as polymerization, oxidation, and hydrolysis, which produce free fatty acids or peroxides [4][5][6] . These can further decompose to small molecular products such as fatty aldehydes, which are highly cytotoxic and may cause harm once they enter the human body [7][8][9][10] . ...
A new turn-on fluorescent probe, based on a hydrazine group placed in the meso-position of the BODIPY molecule, was synthesized. It was then used for detecting long-chain fatty aldehydes, which can be harmful to human health, in edible vegetable oils. In acetonitrile, the probe produced strong “turn on” and 100-fold fluorescence enhancement with high sensitivity and rapid response to saturated fatty aldehydes. A highly sensitive detection method for long-chain fatty aldehydes was established using pre-column derivation fluorescence procedure by high-performance liquid chromatography. The chromatographic method established provided satisfactory precision (1.91%-5.93%), good linearity (R² ≥ 0.999), an acceptable accuracy (83.7%-108%) and a low limit of detection (6.4-12.4 ng/mL). The experimental results indicated that the probe could qualitatively and quantitatively detect six fatty aldehydes in vegetable oils, thus providing the potential for use in routine analysis for identifying the type of vegetable oil and for controlling its quality and safety.
... 350 and 430 mol./L when it was thermally-stressed at 190 °C for prolonged 17.5 and 20.0 hr. durations, respectively [29]. These large differences observed between the HNE contents of fried potato chips and the oils in which they are fried are presumably explicable by the higher reactivity of 4-hydroxy-trans-2-alkenals with HNEscavenging potato chip biomolecules than that of trans-2-alkenals and n-alkanals, and/or an enhanced level of their degradation or further oxidation therein when expressed relative to those for the other aldehyde classes detectable. ...
Exposure of polyunsaturated fatty acid (PUFA)-rich culinary oils (COs) to high temperature frying practices generates high concentrations of cytotoxic and genotoxic lipid oxidation products (LOPs) via oxygen-fueled, recycling peroxidative bursts. These toxins, including aldehydes and epoxy-fatty acids, readily penetrate into fried foods and hence are available for human consumption; therefore, they may pose substantial health hazards. Although previous reports have claimed health benefits offered by the use of PUFA-laden COs for frying purposes, these may be erroneous in view of their failure to consider the negating adverse public health threats presented by food-transferable LOPs therein. When absorbed from the gastrointestinal (GI) system into the systemic circulation, such LOPs may significantly contribute to enhanced risks of chronic non-communicable diseases (NCDs), e.g. cancer, along with cardiovascular and neurological diseases. Herein, we provide a comprehensive rationale relating to the public health threats posed by the dietary ingestion of LOPs in fried foods. We begin with an introduction to sequential lipid peroxidation processes, describing the noxious effects of LOP toxins generated therefrom. We continue to discuss GI system interactions, the metabolism and biotransformation of primary lipid hydroperoxide LOPs and their secondary products, and the toxicological properties of these agents, prior to providing a narrative on chemically-reactive, secondary aldehydic LOPs available for human ingestion. In view of a range of previous studies focused on their deleterious health effects in animal and cellular model systems, some emphasis is placed on the physiological fate of the more prevalent and toxic α,β-unsaturated aldehydes. We conclude with a description of targeted nutritional and interventional strategies, whilst highlighting the urgent and unmet clinical need for nutritional and epidemiological trials probing relationships between the incidence of NCDs, and the frequency and estimated quantities of dietary LOP intake.
... Recently, heme-iron intake was positively associated with CRC and colon adenoma risk in a prospective cohort study [18,19]. Heme-iron from meat plays a role promoting experimental CRC, associated with enhanced luminal lipoperoxidation and leading to the subsequent formation of α-β-unsaturated aldehydes (alkenals), such as 4hydroxynonenal (HNE) from Ω-6 fatty acids [85,86]. A defective mucosal barrier in response to heme exposure, facilitates access to the mucosa for both deleterious luminal heme-induced compounds and opportunistic pathogens, able to promote changes in permeability [87,88], inflammation [89] and genotoxicity [90,91], which are correlated with luminal heme and lipoperoxidation markers and closely associated with a shift in the gut microbiome [92]. ...
Background and purpose: As in many countries, Colorectal Cancer (CRC) incidence and mortality in Uruguay show increasing trends among men but relative stability among women. Dietary iron has shown inconsistencies regarding the CRC risk. Based on iron contents in representative foods, we carried out the present study, in order to accurately analyzing dietary iron and its role in CRC risk. Subjects/methods: A case-control study was performed on 611 CRC incident cases and 2394 controls, using a specific multi-topic questionnaire including a food frequency questionnaire. The sample included 1937 men and 1068 women. Controls were matched by sex and age (± 5 years) to cases. Food-derived nutrients were calculated from available databases. Dietary iron was calculated according to its heme or non-heme source, additionally adjusted by energy. Odds Ratios (OR) was calculated through unconditional logistic regression, adjusting for potential confounders. Animal/plant and heme/non-heme (H/NH) ratios were created for analysis purposes. Results: Total iron intake was inversely associated with CRC risk among men (OR=0.65 for 3 rd vs. 1 st tertile). Heme-iron was inversely associated among women (OR=0.47). Plant-based and non-heme-iron showed an inverse association among men (OR=0.62 and OR=0.60, respectively). Animal-based iron lacked risk association, suggesting opposite trends between sexes. The Animal/Plant iron ratio was directly associated with CRC risk among men (OR=1.77) and inversely associated among women (OR=0.51). The same occurred to the H/NH ratio, whose risks increased among men (OR=1.53) but decreased among women (OR=0.53). Conclusion: Dietary iron showed different associations with CRC risk, regarding iron source and sex. The available iron type, due to its wide hormonal, red-ox, and metabolic interactions, might play also different roles linked to colorectal carcinogenesis. Nevertheless, the different associations observed for each sex demand further studies to clarify this point.
This study assessed the stability of commonly used frying oils submitted to a specific heat treatment. Gas chromatographic analysis (GC-FID) revealed a decrease in the content of polyunsaturated fatty acids (PUFAs) and production of linolelaidic acid (18: 2n-6t). Furthermore, electrospray ionization mass spectrometry (ESI-MS) analysis demonstrated that the triacylglycerol (TAG) content of molecules composed of linoleic acid (L), oleic acid (O), and linolenic acid (Ln) exhibited the greatest decrease during heating. Among the evaluated vegetable oils, soybean oil exhibited the lowest temperature of stability. Conversely, the lowest concentration of trans-fatty acids (TFA) was observed for canola oil.
Antioxidant activity of bicarbonates and carbonates including NaHCO3, Na2CO3, KHCO3, and K2CO3 was evaluated in soybean oil (SBO) at 180°C. KHCO3 and K2CO3 had stronger activity than NaHCO3 and Na2CO3. KHCO3 (5.5 mEq/L, 0.060 wt.%) and K2CO3 (5.5 mEq/L, 0.041 wt.%) were more effective than 0.02 wt.% tert‐butylhydroquinone (TBHQ) in preventing oxidation of SBO. While the antioxidant activity of KHCO3 and K2CO3 increased with increasing their concentrations up to 5.5 mEq/L, it decreased at 11 mEq/L. KHCO3 and K2CO3 were also effective in preventing oxidation of other vegetable oils including avocado, canola, corn, high oleic soybean, and olive oils. Correlation tests conducted with the results from the six oils showed that KHCO3 and K2CO3 had weak to moderate positive correlations with γ‐ and δ‐tocopherols. In a separate study in stripped SBO, it was found that KHCO3 had a synergistic effect with α‐tocopherol, but not with γ‐ and δ‐tocopherols. KHCO3 had additive or synergistic effect with rosemary extract, epigallocatechin gallate, ascorbic acid, and ascorbyl palmitate. Antioxidant activity of KHCO3 was confirmed in frying of potato cubes in SBO and canola oil. Although more studies should be conducted for better understanding of the mechanisms and factors affecting the antioxidant activity of bicarbonates and carbonates, this study demonstrated that they could serve as antioxidants or co‐antioxidants of other antioxidants in frying. Inorganic salts including NaHCO3, KHCO3, Na2CO3, and K2CO3 hadstrong antioxidant activity in vegetable oils at frying temperatures when they wereadded as powder. Antioxidant activity of 0.06 wt.% KHCO3 was higherthan that of 0.02 wt.% TBHQ in soybean oil and canola oil during frying potato. KHCO3 had additive orsynergistic effect with rosemary extract, epigallocatechin gallate, ascorbicacid, and ascorbyl palmitate indicating that these inorganic salts can be usedas co‐antioxidants to enhance the antioxidant activity of existing antioxidantswhile they can be used alone as well.
To compare the oxidation products of four types of vegetable oils (palm oil, soybean oil rapeseed oil, and flaxseed oil) during thermal processing, lipidomics, volatolomics and simulation analyses were integrated to investigate the evolution of volatile profiles. The evolution of volatile profiles in different vegetable oils were found to be different, which are attribute to their different lipid composition. There were potential markers of palmitic acid-based vegetable oils as undecanal, dodecanal and 2-hexanone. A potential marker of oleic acid-based vegetable oils was 2-undecenal. (E,E)-2,4-nonadienal, 3-octen-2-one, and 3-nonen-2-one were potential markers of linoleic acid-based vegetable oils. The potential markers of linolenic acid-type vegetable oils were 1-penten-3-ol, (E)-2-butenal, (E)-2-pentenal, (E,E)-2,4-heptadienal (1), (E,E)-2,4-heptadienal (2), 2-ethyl-furan (1), 2-pentanone, and 3-hexen-2-one. The present study provides a new and comprehensive strategy to elucidate the changes of volatile compounds in thermal processed vegetable oil.
Previous studies reported that several amino acids had strong antioxidant activity in vegetable oils under frying conditions. In this study, amino acids were converted to their sodium or potassium salts, and a heating study was conducted with 5.5 mM amino acid salts in soybean oil (SBO) at 180°C. Sodium salts of amino acids including alanine, phenylalanine, and proline and disodium glutamate had significantly stronger antioxidant activity than the corresponding amino acids, and potassium salts had stronger antioxidant activity than sodium salts. Potassium salts of alanine and phenylalanine more effectively retained tocopherols in SBO than the corresponding amino acids during heating. Phenylalanine potassium salt had stronger antioxidant activity than phenylalanine in other vegetable oils including olive, high oleic soybean, canola, avocado, and corn oils. Phenylalanine potassium salt at 5.5 mM more effectively prevented oil oxidation than tert‐butyl hydroquinone, a synthetic antioxidant, at its legal concentration limit (0.02%) indicating its feasibility as a new antioxidant for frying.
The detection of benzo(a)pyrene (BaP), a strong carcinogen, in edible oil has been widely reported. This work studied the concentration of BaP in different parts of tea seeds generated during roasting from a new perspective. A novel method was established and used to calculate the actual generated concentration of BaP, which is different from the previous direct determination of BaP concentration and also takes into account the concentration of the lost BaP. The results showed that the loss rate of BaP in husks was the highest (92.7%), while that in the peeled tea seeds was the lowest (66.9%). Conversely, the generated concentration of BaP in peeled seeds was the highest (6.7 μg·kg-1), while that in husks was the lowest (2.8 μg·kg-1). The change in concentration of BaP during roasting was mainly related to the components of different parts of tea seeds. Finally, the lost BaP-d12 in tea seeds was detected in other parts of the semi-closed simplified model, which confirmed that BaP will migrate during roasting. This work emphasised that it was necessary to modify the calculation method for the generated concentration of BaP in food during thermal processing, which will be helpful to explore the generation mechanism of BaP.
The activated carbons (ACs) from shells of horse chestnut, chestnut, acorn, pistachio, apricot kernel, and wood shavings were evaluated to recover used oil (UO). The effects of the amount of AC, adsorption time, and temperature on the purification of the UO were investigated using the apricot kernel shells due to the high apricot production of Turkey. Kinetic evaluation was also done. The percentage improvements (PIs) in total polar materials (TPM), free fatty acids (FFA), p‐anisidine value (p‐AV), conjugated diene content (CD), and color of UO were found as 100, 56, 92, 51, and 90% for the apricot kernel AC in the column treatment. The most effective other ACs in decreasing FFA, p‐AV, CD, and color were the horse chestnut (59%), chestnut (74%), chestnut (43%), and pistachio (72%), respectively. Consequently, these ACs can be used for the purification of UO.
The oxidation process of soybean oil enriching with the phenolic extract of Camellia oleifera seed cake (PE), tertiary butylhydroquinone (TBHQ) and tea polyphenol palmitate (TPP) was evaluated under frying condition with ¹H nuclear magnetic resonance (NMR). The results showed that PE and TBHQ could inhibit the degradation of unsaturated acyl groups and reduce the generation rate and concentration of oxidative compounds, with PE having better performance. The hydroperoxides and their associated (Z,E)- and (E,E)-conjugated dienes of soybean oil were only detected at 220 min, and soybean oil with PE had the lower intensity of ¹H NMR signals. In addition, the nine individual polyphenols significantly reduced during frying, and only three phenolic acids were detected even after 420 min, although their content was extremely low. All results suggested that phenolic extracts could provide an effective alternative to synthetic antioxidants during the frying process.
This study investigated the toxic effects of trans,trans-2,4-decadienal (tt-DDE) on vascular endothelial cells as well as the underlying mechanisms involved. Human umbilical vascular endothelial cells (HUVECs) were treated with different concentrations of tt-DDE for 24 h, and cell viability, colony formation ability, apoptosis, mitochondrial function and autophagy pathway were determined. The results showed that tt-DDE dose-dependently inhibited cell viability and colony formation, and increased lactate dehydrogenase (LDH) release and apoptosis in HUVECs. Besides, tt-DDE exposure induced extensive mitochondrial damage, as evidenced by the decreased mitochondrial DNA copy number, ATP synthesis, and mitochondrial membrane potential, and increased mitochondrial reactive oxygen species (ROS) production and cytochrome c release from mitochondria. tt-DDE also induced mitochondrial fragmentation and fission by increasing DNM1L protein expression and DNM1L mitochondrial translocation. Additionally, tt-DDE treatment resulted in the blockage of autophagic flux and accumulation of autophagosomes in endothelial cells. Further investigation revealed that the inhibition of autophagy by 3-methyladenine aggravated tt-DDE-induced mitochondrial dysfunction and cell injury. However, scavenging of ROS by N-acetyl-l-cysteine (NAC) significantly prevented tt-DDE-induced mitochondrial damage, autophagy dysfunction, and cell injury. These data indicated that tt-DDE induced endothelial cell injury through impairing mitochondrial function and autophagic flux.
This study investigated the effects of frying of foods on the fatty acids and formation of carbonyl compounds in frying soybean oils. Rice cakes and hairtails were selected as typical starch/protein-based foods for frying using soybean oil. In this study, fifteen carbonyl compounds were detected by an efficient high performance liquid chromatography (HPLC) developed by this paper. During frying with rice cakes or hairtails, the linolenic acid in frying oils was reduced by approximately 20% compared with that in the no-food frying system. Fewer types of carbonyl compounds (frying without food: 11; frying of rice cakes: 9; frying of hairtails: 6) were detected, and the levels of some carbonyl compounds such as trans-2-nonenal were decreased. Results suggested that frying rice cakes or hairtails can substantially influence the contents of fatty acids and the formation of carbonyl compounds in frying oils. This study provides references for evaluating the quality of fried oil and food.
Aldehydes are known carcinogens and irritants that can negatively impact health. They are present in tobacco smoke, the environment, and food. The prevalence of aldehyde exposure and potential health impact warrants a population-wide study of serum aldehydes as exposure biomarkers. We analyzed 12 aldehydes in sera collected from 1843 participants aged 12 years or older in the 2013-2014 National Health and Nutrition Examination Survey. Several aldehydes were detected at high rates, such as isopentanaldehyde (99.2%) and propanaldehyde (88.3%). We used multiple linear regression models to examine the impact of tobacco smoke and dietary variables on serum concentrations of isopentanaldehyde and propanaldehyde. Although 12 serum aldehydes were analyzed and compared to tobacco smoke exposure, only isopentanaldehyde and propanaldehyde showed any significant association with tobacco smoke exposure. Survey participants who smoked 1-10 cigarettes per day (CPD) had 168% higher serum isopentanaldehyde and 28% higher propanaldehyde compared with nonusers. Study participants who smoked 11-20 CPD had higher serum isopentanaldehyde (323%) and propanaldehyde (70%). Similarly, study participants who smoked >20 CPD had 399% higher serum isopentanaldehyde and 110% higher serum propanaldehyde than nonexposed nonusers. The method could not, however, differentiate between nonexposed nonusers and nonusers exposed to secondhand smoke for either of these two aldehydes. No dietary variables were consistently predictive of serum isopentanaldehyde and propanaldehyde concentrations. This report defines baseline concentrations of serum aldehydes in the U.S. population and provides a foundation for future research into the potential health effects of aldehydes. In addition, this study suggests that tobacco smoke is a significant source of exposure to some aldehydes such as isopentanaldehyde and propanaldehyde.
Lipid peroxidation-derived reactive carbonyl species (RCS) such as acrolein and 4-hydroxynonenal pose health risks. We characterized the RCS-scavenging reactions of tea catechins in an aqueous solution and in baked cake. Acrolein’s reaction with each of the major tea catechins (epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate) resulted in the formation of mono-, di-, and tri-acrolein conjugates of each catechin as revealed by our LC-linear ion trap MS analysis. The formation of the acrolein-conjugates of the four catechins was confirmed in the reaction of acrolein with green tea powder (matcha) extract. The addition of matcha tea powder to cake dough significantly suppressed the accumulation of RCS during cake baking. The mono-acrolein conjugates of the four major catechins were detected in the baked cake. The RCS-scavenging capability of tea catechins offers a new functionality of matcha tea powder, and its heat stability demonstrates the usefulness of matcha as a food additive.
Undoubtedly, significant advances were performed concerning 4-hydroxy-2-alkenals research on foods, and their formation by double oxidation of polyunsaturated fatty acids. But further studies are still needed, especially on their occurrence in foods enriched with n-3 and n-6 fatty acids, as well as in foods for infants and processed foods. Major factors concerning the formation of 4-hydroxy-2-alkenals were discussed, namely the influence of fatty acids composition, time/temperature, processing conditions, salt, among others. Regarding mitigation, the most effective strategies are adding phenolic extracts to foods matrices, as well as other antioxidants, such as vitamin E. Exposure assessment studies revealed 4-hydroxy-2-alkenals values that could not be considered a risk for human health. However, these toxic compounds remain unaltered after digestion and can easily reach the systemic circulation. Therefore, it is crucial to develop in vivo research, with the inclusion of the colon phase, as well as, cell membranes of the intestinal epithelium. In conclusion, according to our review it is possible to eliminate or effectively decrease 4-hydroxy-2-alkenals in foods using simple and economic practices.
Edible oils oxidize during microwave heating, which may affect their nutritional value and safety. Exploring the oxidation mechanisms of unsaturated fatty acids in edible oils to determine which are suitable for microwave heating is therefore important. We used GC-MS, low-field NMR, and ¹H NMR techniques to study functional-group oxidation, the unsaturated fatty acid change law, and the distribution and migration of protons in various functional groups of four common vegetable cooking oils during microwave treatment. We show that the acid values of sunflower, soybean, peanut, and corn oil increased by 14%, 31%, 36%, and 101%, respectively, while the concentrations of malondialdehyde increased by 115%, 664%, 158%, and 333%, respectively, and the peroxide value fluctuated with increasing microwave power. The C16:0 concentrations of all four edible oils increased by more than 50%, and the concentration of polyunsaturated fatty acids decreased by more than 30% during microwave treatment; hence sunflower oil is the most suitable of the above-mentioned oils for daily microwave heating. In addition, we recommend the use of three characteristic functional groups to monitor the oxidative changes undergone by oils: olefinic H (CH = CH), diallyl CH2 (CH = CH–CH2–CH = CH), and allyl CH2 (CH = CH–CH2).
To demonstrate the oxidation evolution and thermal stability of blended oils during the deep-frying process, the relationship between unsaturated fatty acids, the distribution and migration of H protons and functional groups was investigated. The results showed that blended oils had high onset and peak oxidation temperature, and the peroxide value, p-anisidine value and polar compounds were low due to high tocopherols, which implied that blended oils had better thermal stability. The levels of linoleic and linolenic acids decreased significantly, as well as the ratio of C18:2/C16:0 except sunflower seed oil blended with raspberry seed oil. Moreover, there was also a significant decrease in relaxation times T22 and T23. The ratios of olefinic H, bisallylic CH2, allylic CH2 relative to glyceride CH2 slowly decreased along with the increase of Rab and Rao, except corn oil blended with raspberry seed oil. For corn oil blended with raspberry seed oil, the ratio of olefinic H, bisallylic CH2, allylic CH2 increased and then slowly decreased. Rao, Rab and Raa reached the highest value on the forth day, then decreased, and Rab was higher than Rao and Raa. In addition, T22, T23 and functional groups significantly correlated with unsaturated fatty acids.
Formation of toxic alkylbenzenes, total polar compounds (%TPC) and degradation of tocochromanol are monitored. Analyses of the oil extracted from fried potatoes confirm the trend observed in the frying oil. The fresh oil has a TPC content of 3%, which increases with the frying time, exceeding the acceptable value (25%) after about 25 h for deep‐frying and 1.5 h for pan‐frying. During deep‐frying, total tocochromanol decreases to about half (25 mg per 100 g) of the initial value, pan‐frying shows faster, degradation (complete after 1.5 h). Toluene concentration increases with the frying time reaching a maximum, and afterwards gradually decreases. Except for butylbenzene during pan‐frying, pentylbenzene and butylbenzene concentration, increase with the frying time, but remain much lower than toluene.
Practical Applications: This is the first systematic work comparing alkylbenzenes evolution under different frying conditions. Different from previous works, frying experiments are carried out following the indication of many European countries that recommend using temperature lower than 180 °C. The amount of alkylbenzenes assumed through a standard portion of fried potatoes (200 g) is assessed, which is relevant for evaluating dietary exposure to these contaminants.
Consumer preferences, labeling mandates, and dietary health concerns are driving changes to ingredient selection within the food industry. Many conventional oilseeds are being selected or genetically modified to improve the seed oil fatty acid composition ranging from raising/lowering saturates or unsaturates to incorporating new fatty acids abundant in other species. Most of these new oils have significant improvements over their commodity oil counterparts. This article reviews the most common and commercially viable new oilseed varieties providing trait‐modified oils developed within the last 10–15 years.
Background
Lipid peroxidation yields a large number of aldehydes and carbonyl-containing compounds, of which the reactive and toxic compound 4-hydroxy-2-nonenal (4-HNE) derived from ω-6 polyunsaturated fatty acids (ω-6 PUFAs) is the most extensively studied. The high reactivity of 4-HNE enables this compound to crosslink with various biomolecules and thus contribute to the pathological processes of several diseases, such as atherosclerosis, cancer, diabetes mellitus, and neurodegenerative disorders.
Scope and approach
From the perspective of food safety, the emergence of lipid peroxidation contaminants in foodstuffs remains a major concern of consumers, health departments, and industries. This review highlights the latest developments regarding the formation pathways, toxicity, analysis methods, occurrence in foodstuff, and mitigation strategies for 4-HNE. Future prospects on measuring and controlling 4-HNE in food are also discussed.
Key findings and conclusions
The determination of 4-HNE levels in different types of foods indicates that PUFAs-rich vegetable oil and oil-based food are major intake sources of 4-HNE. Considering the toxicity of 4-HNE, sensitive detection techniques combined with feasible control methods should be an effective solution for food quality maintenance and safety assurance. However, current detection methods and 4-HNE control strategies possess inherent advantages and limitations. Therefore, effective 4-HNE detection and new controlling technologies that are practically viable at the industrial level need to be developed.
The present work investigated the formation of three toxic aldehydes, malondialdehyde (MDA), 4‐hydroxy‐hexenal (HHE), and 4‐hydroxy‐nonenal (HNE), during deep‐frying of different foods in corn oil (CO), rapeseed oil (RO), and linseed oil (LO). Besides, their contents in French fries (FF), and fried chicken breast meat (FCBM) were also explored. Results showed that the MDA/HHE/HNE levels in frying groups were all lower than those in control, indicating the incorporation into the fried foods. Apart from the different levels, MDA/HHE/HNE in FF and FCBM possessed similar variation tendencies, revealing the matrix‐mediated distribution. The combined exposure assessment based on the threshold of toxicological concern (TTC) levels were conducted, and risks of exceeding the limitation values (1.5 μg/kg bw/day) for HNE in CO, and HHE in LO were exhibited. The consumption of both FF and FCBM should be regulated, considering the levels of MDA, HHE, and HNE these fried foods may contain.
Emissions of volatile organic compounds, including aldehydes, formed during heating of cooking oils: coconut, safflower, canola, and extra virgin olive oils were studied at different temperatures: 180, 210, 240, and 240°C after 6h. Fumes were collected in Tedlar® bags and later analysed by GC–MS. The emissions of volatiles were constant with time and increased with the oil temperature. When the temperature of the oil was above its smoke point, the emission of volatiles drastically increased, implying that oils with low smoke point, such as coconut, are not useful for deep-frying operations. Canola was the oil generating the lowest amount of potentially toxic volatile chemicals. Acrolein formation was found even at low temperatures, indicating that home cooking has to be considered as an indoor pollution problem.
Two epimers of methyl (12S,13S)-(E)-12,13-epoxy-9-hydroperoxy-10-octadecenoate were isolated after esterification of a mixture of fatty acids obtained from
decomposition of (13S)-(9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid by an Fe++-cysteine catalyst. These epimeric epoxyhydro-peroxyoctadecenoates were decomposed by heat (210 C) in the injection port of
a gas chromatograph, and the cleavage fragments were subsequently separated by gas chromatography (GC) and identified by mass
spectrometry (MS). Among the scission products obtained, the most prominent in the GC peak profile were methyl octanoate and
methyl 9-oxononanoate. Other peaks were identified as pentane, 1-pentanol, hexanal, 2-heptanone, 2-pentylfuran, methyl heptanoate,
2-octenal, 4,5-epoxy-2-decenal, methyl 8-(2-furyl)-octanoate, 11-oxo-9-undecenoate and methyl 13-oxo-9,11-tridecadienoate.
In addition, 3,4-epoxynonanal, methyl 8-oxooctanoate, 3-hydroxy-2-pentyl-2,3-dihydrofuran and methyl 10-oxodecanoate were
tentatively identified. Except for the furan compounds, the formation of the fragmentation products could be explained by
conventional free-radical scission mechanisms.
Volatile aldehydes were generated in the exhaust of high-oleic safflower oil during heating at 180°C by spraying water into
atmospheres with four levels of oxygen concentrations (2, 4, 10, and 20%). These aldehydes were quantitatively analyzed by
HPLC after the conversion to 2,4-dinitrophenyl hydrazones. Ten alkanals (C2 through C10), eight 2-alkenals (C3 through C10) and three 2,4-alkadienals (C7, C9, and C10) were found. These aldehyde levels were found to be positively correlated with both the heating time and the atmospheric
oxygen concentration. The total amounts of aldehydes were the lowest in the oil heated in an atmosphere with 2% O2, and corresponded to 1/10 of those in the atmosphere with 20% O2. Acrolein was not found in oils heated in the atmosphere with 2% oxygen. These results suggest that frying in atmospheres
with low oxygen levels can effectively decrease the generation of volatile aldehydes in the exhaust.
In previous work with soybean (Glycine max), it was reported that the initial product of 3Z-nonenal (NON) oxidation is 4-hydroperoxy-2E-nonenal (4-HPNE). 4-HPNE can be converted to 4-hydroxy-2E-nonenal by a hydroperoxide-dependent peroxygenase. In the present work we have attempted to purify the 4-HPNE-producing oxygenase from soybean seed. Chromatography on various supports had shown that O2 uptake with NON substrate consistently coincided with lipoxygenase (LOX)-1 activity. Compared with oxidation of LOX's preferred substrate, linoleic acid, the activity with NON was about 400- to 1000-fold less. Rather than obtaining the expected 4-HPNE, 4-oxo-2E-nonenal was the principal product of NON oxidation, presumably arising from the enzyme-generated alkoxyl radical of 4-HPNE. In further work a precipitous drop in activity was noted upon dilution of LOX-1 concentration; however, activity could be enhanced by spiking the reaction with 13S-hydroperoxy-9Z, 11E-octadecadienoic acid. Under these conditions the principal product of NON oxidation shifted to the expected 4-HPNE. 4-HPNE was demonstrated to be 83% of the 4S-hydroperoxy-stereoisomer. Therefore, LOX-1 is also a 3Z-alkenal oxygenase, and it exerts the same stereospecificity of oxidation as it does with polyunsaturated fatty acids. Two other LOX isozymes of soybean seed were also found to oxidize NON to 4-HPNE with an excess of 4S-hydroperoxy-stereoisomer.
Thermal stressing of polyunsaturated fatty acid (PUFA)- rich culinary oils according to routine frying or cooking practices generates high levels of cytotoxic aldehydic products (predominantly trans-2-alkenals, trans,trans-alka-2,4-dienals, cis,trans-alka-2, 4-dienals, and n-alkanals), species arising from the fragmentation of conjugated hydroperoxydiene precursors. In this investigation we demonstrate that typical trans-2-alkenal compounds known to be produced from the thermally induced autoxidation of PUFAs are readily absorbed from the gut into the systemic circulation in vivo, metabolized (primarily via the addition of glutathione across their electrophilic carbon-carbon double bonds), and excreted in the urine as C-3 mercapturate conjugates in rats. Since such aldehydic products are damaging to human health, the results obtained from our investigations indicate that the dietary ingestion of thermally, autoxidatively stressed PUFA-rich culinary oils promotes the induction, development, and progression of cardiovascular diseases.
The oxidative deterioration of glycerol-bound polyunsaturated fatty acids (PUFAs) in culinary oils and fats during episodes of heating associated with normal usage (30-90 min at 180 degrees C) has been monitored by high field 1H NMR spectroscopy. Thermal stressing of PUFA-rich culinary oils generated high levels of n-alkanals, trans-2-alkenals, alka-2,4-dienals and 4-hydroxy-trans-2-alkenals via decomposition of their conjugated hydroperoxydiene precursors, whereas only low concentrations of selected aldehydes were produced in oils with a low PUFA content, lard and dripping when subjected to the above heating episodes. Samples of repeatedly used, PUFA-rich culinary oils obtained from restaurants also contained high levels of each class of aldehyde. The dietary, physiological and toxicological ramifications of the results obtained are discussed.
Sunflower oil at a specific oxidation stage (when several oxygenated alpha,beta-unsaturated aldehydes are generated, mainly 4-hydroperoxy-trans-2-alkenals and 4-hydroxy-trans-2-alkenals), caused at 70 degrees C with aeration for 7 days, was administered intraperitoneally to rats. This oil was studied by means of solid phase micro-extraction followed by gas chromatography/mass spectrometry (SPME-GC/MS) and by proton nuclear magnetic resonance ((1)H-NMR). Oxidized sunflower oil (3 ml/kg/day) was administered to male Sprague-Dawley rats for 21 days. The control group was administered non-oxidized sunflower oil in the same volume and for the same duration as the experimental group. A significant decrease in the number of neural cells positively immunostained for TrkA receptor was detected in the frontal cortex of the experimental group, with respect to controls, suggesting both neuronal damage as well as a deficit in neuronal survival signalling at this level. This could lead to apoptosis of cholinergic neurons, which play a key role in memory and attention function. These results indicate that toxic substances present in the oxidized sunflower oil, among them 4-hydroxy-trans-2-nonenal (HNE) and 4-hydroperoxy-trans-2-nonenal (HPNE), could disrupt survival signalling of frontal cortex cholinergic neurons, which could lead to apoptosis and neurodegenerative diseases. In the case of humans, this fact reinforces the necessity of avoiding the re-utilization of oxidized sunflower oil, in order to contribute to long-term neurodegenerative diseases prevention.
1. Methods using t.l.c. and high-pressure liquid chromatography (h.p.l.c.) have been used to separate the complex variety of substances possessing a carbonyl function that are produced during lipid peroxidation. 2. The major type of lipid peroxidation studied was the ADP-Fe2+-stimulated peroxidation of rat liver microsomal phospholipids. Preliminary separation of the polar and non-polar products was achieved by t.l.c.: further separation and identification of individual components was performed by h.p.l.c. Estimations were performed on microsomal pellets and the supernatant mixture after incubation of microsomes for 30 min at 37 degrees C. 3. The polar fraction was larger than the non-polar fraction when expressed as nmol of carbonyl groups/g of liver. In the non-polar supernatant fraction the major contributors were n-alkanals (31% of the total), alpha-dicarbonyl compounds (22%) and 4-hydroxyalkenals (37%) with the extraction method used. 4. Major individual contributors to the non-polar fraction were found to be propanal, 4-hydroxynonenal, hexanal and oct-2-enal. Other components identified include butanal, pent-2-enal, hex-2-enal, hept-2-enal, 4-hydroxyoctenal and 4-hydroxyundecenal. The polar carbonyl fraction was less complex than the non-polar fraction, although the identities of the individual components have not yet been established. 5. Since these carbonyl compounds do not react significantly in the thiobarbituric acid reaction, which largely demonstrates the presence of malonaldehyde, it is concluded that considerable amounts of biologically reactive carbonyl derivatives are released in lipid peroxidation and yet may not be picked up by the thiobarbituric acid reaction.
Since the first edition of Deep Frying was published in 1996, there have been many changes to the U.S. Dietary Guidelines and nutritional labeling laws, and improvements in frying technology and practices have made a significant impact on the industry. This book will cover everything you need to know to create fat and oil ingredients that are nutritious, uniquely palatable and satisfying.
There has been increased recognition that improper use of frying fats degrades the fat and reduces the quality of fried food. However, there are no worldwide regulations and guidelines for control of frying fat. Although no regulations have been established in the United States, a number of European countries promulgated specific laws and regulations. In addition, the Swedish Food Regulations include an ordinance with general advice on how to handle frying fat and oil. Deep fat frying is a complex method of food preparation in which many reactions occur, resulting in oxidative and hydrolytic degradation and polymerization of the oil. Many studies in the past 50 years showed that thermally oxidized oil affects the growth of test animals. Conversely, additional studies indicated that optimal frying conditions cause no significant change in the fatty acid composition of the frying oil and no toxicity in test animals. Formal laws and regulations for control of frying fat quality have been adopted by only a few countries. Several other countries, however, employ practical guidelines and test procedures to control the quality of frying fats and fried food. In addition, there is increasing awareness that good frying practice and proper control of frying fat improve the quality and acceptability of fried food. Guidelines for handling frying fat and on-site tests to check fat quality are useful tools for overall food sanitation and quality control programs worldwide.
Mixtures of either sunflower oil or thermodegraded sunflower oil and a standard meal were submitted to an in vitro digestion model. The same experiment was carried out with fluid deep-frying fat and thermodegraded fluid deep-frying fat. The thermodegradation of the oil and fat was provoked by submitting them to 190 degrees C with aeration in a convection oven, and the presence in the headspace of the thermodegraded oil and fat of oxygenated alpha,beta-unsaturated aldehydes (OalphabetaUAs), such as 4-hydroxy-2-nonenal (HNE), 4-oxo-2-nonenal (ONE), and 4,5-epoxy-2-decenal (EDE), was monitored by solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). The digestion products were separated by centrifugation in a lipidic phase, an aqueous phase, and a pellet phase. The headspace of these three phases was also studied by SPME/GC-MS to check if the toxic and very reactive OalphabetaUAs above-mentioned remained unaltered after the in vitro digestion process or if they had reacted with the various compounds present in the digestion products, so disappearing from the samples. With the same aim the extract in ethyl acetate of the aqueous and pellet phases, and of the lipidic phase after dilution, were studied by GC-MS. All results obtained showed that a certain proportion of the toxic OalphabetaUAs remains unaltered after digestion, dispersed in the three phases above-mentioned, and thus are bioaccessible in the gastrointestinal tract and so could reach the systemic circulation. Compounds that may originate in Maillard type reactions (2-pentylpyridine) are found among digestion products, proving that these reactions are possible in this process if adequate substrates are present. In addition, it has been shown that toxic metabolites from the synthetic antioxidant BHT, present in fat before digestion, remain unaltered after this process and could reach the systemic circulation.
Humans are exposed to oxidized fats in the diet from fatty fish and fish oils, deep fat frying and powdered foods. Air-oxidized fish oils can induce toxic symptoms by stressing the vitamin E antioxidant system. Although primary hydroperoxides and lipid polymers produced from thermally stressed oils are not toxicologically important, toxic effects may be induced by secondary lipid peroxides. Recent studies indicate that thermally stressed oils may have a role in the acceleration of atherosclerosis. There is increasing evidence that cholesterol oxides found in some deep fat fried and dehydrated foods can exert atherogenic effects. Weak mutagenic activity has also been detected in deep-fried fats, although the toxicological significance is unclear.
Thermal degradation of several possible precursors of the intense flavor compoundtrans-4,5-epoxy-(E)-2-decenal in model experiments revealed that the odorant is formed in significant yields from 13-hydroperoxy-9,11-octadecadienoic
acid (13-HPOD) and 9-hydroperoxy-10,12-octadecadienoic acid (9-HPOD). Of these hydroperoxides, arising in equal amounts during
autoxidation of linoleic acid, the 9-HPOD was established as the more effective precursor. The key intermediates in the generation
of the epoxyaldehyde were found to be 2,4-decadienal, arising from 9-HPOD, and 12,13-epoxy-9-hydroperoxy-10-octadecenoic acid,
a degradation product of 13-HPOD. Isolation and characterization of the precursors from a baking margarine confirmed glycerine-bound
9- and 13-HPOD as the intermediates in the formation of the epoxyaldehyde during heating of fats that contain linoleic acid.
A few odor-active epoxyaldehydes, formed during lipid peroxidation, have recently been reported as intense aroma compounds in foods. However, very little is known about their flavor properties in general. Syntheses of homologous trans-2,3-epoxyalkanals (C(6)-C(12)) and trans-4,5-epoxy-(E)-2-alkenals (C(7)-C(12)) followed by structural characterization using mass spectrometry (MS/EI; MS/CI) and (1)H NMR measurements were performed. An evaluation of their odor qualities and odor thresholds by gas chromatography-olfactometry revealed the following: within the trans-2,3-epoxyalkanals, the odor quality changed from grassy for the compounds with six and seven carbon atoms to citrus-like or soapy for aldehydes with eight and more carbon atoms. The odor thresholds lay in the range of 3-15 ng/L (in air) and were nearly identical within the series; however, a slight minimum was measured for trans-2,3-epoxyoctanal to trans-2,3-epoxydecanal. In the series of the trans-4,5-epoxyalk-(E)-2-enals the C(10) compound was characterized by the lowest odor threshold of 0.6-2.5 pg/L of air. However, all trans-4,5-epoxy-alk-(E)-2-enals smelled intensely metallic.
Relationships between the time at which edible oils reach 25% in weight of polar compounds and their original composition, expressed as molar percentage of their acyl groups, were tested; the aim was to analyze the influence of oil composition on its performance at high temperature. Likewise, relationships between the composition of the oils and their original percentage in polar compounds were explored. It has been shown for the first time that a very close relationship between the percentage in weight of polar compounds of the original oils, and the time at which they reach 25% of polar compounds exits. This relationship permits the prediction, in a very simple, fast and non-destructive way, of the performance of edible oils at frying temperature from their original percentage in polar compounds, in other words from their original dielectric constant. This approach is very useful for food safety, with important technological and economic repercussions.
The volatile constituents of used frying oils obtained from a local food-processing plant were isolated by simultaneous distillation−extraction and fractionated by silica gel column chromatography. The isolates were analyzed by capillary gas chromatography and combined capillary gas chromatography−mass spectrometry, resulting in the identification of 140 compounds. The major constituents identified were 1-pentanol, hexanal, furfuryl alcohol, (E)-2-heptenal, 5-methylfurfural, 1-octen-3-ol, octanal, 2-pentylfuran, (E)-2-octenal, nonanal, (E)-2-nonenal, and hexadecanoic acid. Keywords: Frying oil; volatiles; simultaneous steam distillation−extraction; deep-fat frying
As part of our efforts to identify volatile decomposition products in used frying oils, a series of 4-and 5-oxoaldehydes were synthesized, purified, and characterized by gas chromatography, gas chromatography - mass spectrometry, gas chromatography-Fourier transform infrared spectrometry, and nuclear magnetic resonance spectrometry. Oxoaldehydes have been proposed as possible precursors of alkylfurans, which have potential anticancer effects. In a model reaction 4-oxononanal was refluxed in hexane for 40 days and only trace amounts of 2-pentylfuran were produced, suggesting that it is not a major precursor of the furan. The volatile constituents of used frying oils obtained from commercial food processors were studied, and 4-oxohexanal, 4-oxooctanal, 4-oxononanal, and 4-oxodecanal were identified.
The volatile compound produced in greatest yield from the aerobic incubation at 35°C for 35 h of a mixture of butterfat, cupric palmitate and α-tocopherol was characterised by chromatography and spectroscopy. The same compound was also isolated from a similar reaction mixture containing cod-liver oil instead of butterfat. The compound was identified as trans-4,5-epoxyhept-trans-2-enal and was found to have the same properties as that synthesised by the epoxidation of hepta-trans-2,trans-4-dienal. Volatile epoxyalkenals of this type have not been previously identified as products from lipid oxidation.
1H NMR spectra of 66 samples of edible oils from 14 different botanical origins were acquired. Assignment of signal spectra to the different types of hydrogen atoms was made and the areas of the signals determined. Considering that the area of the signals of the spectra is proportional to the number of hydrogen atoms of each type in the sample, it is possible to calculate not only the iodine value, but also the proportion of different acyl groups from the data. Determination of both parameters requires only a few minutes and one spectroscopic run. Classical methodology however, requires two separate wet methods for determining the unsaturation degree (iodine value) and the proportions of different acyl groups; both of them involve chemical transformations of the sample and considerable time and cost. Determination of acyl group proportions in samples by 1H NMR, which was validated with mixtures of standard triglycerides, provides accurate results and is able to detect small differences between samples of very similar composition.
Several samples containing different proportions of standard compounds such as tristearin, triolein, trilinolein, and trilinolenin, covering a broad range of compositions, some similar to those of edible oils, were prepared by weight. The 1H nuclear magnetic resonance (NMR) spectra of these samples were recorded and their signals were assigned. It was shown that concentrations of linolenic acyl groups close to 0.4% or higher can be detected by this technique. The area of 5 discrete proton signals of the spectrum was determined. Considering the ratio between this area and the concentration of the corresponding types of hydrogen atoms in the sample, equations calculating the proportions of the acyl groups were deduced. The high level of agreement between data coming from 1H NMR spectra and data obtained by weight shows the usefulness of this methodology. In addition, it has the advantage that it is very fast and simple in comparison with the classical methods, and does not require a chemical modification of the sample. For this reason, the described method constitutes a valuable alternative for the determination of the proportions of different acyl groups in acylglycerol mixtures, such as, for example, oils and fats.
The purpose of the present study was to compare the emission of volatile aldehydes from diacylglycerol-rich oils (DAG-OILs)
and triacylglycerol-rich oils (TAG-OILs) with different degrees of unsaturation of fatty acid moieties during the deep-frying
of sliced potatoes. To examine the effect of fatty acid composition, four kinds of oils with different fatty acid compositions
were selected: rape seed (RS); sunflower oil as a high oleic (HO); safflower oil as high linoleic (HL); and, perilla oil as
high linolenic (HLn) oils. The emissions of volatile aldehydes were determined during the deep-frying of sliced potatoes by
using the above fresh test oils or deteriorated RS oils. The statistical analysis showed no significant difference in volatile
aldehyde emission and profile between the DAG-OIL and TAG-OIL with the fatty acid composition of RS, HL, and HLn. Although
a statistically significant difference was noted in the volatile aldehyde emission between the DAG-OIL and TAG-OIL with HO,
this difference was extremely small when compared to the variations found in the oils with four types of fatty acid composition.
Finally, no difference was found in the volatile aldehyde emissions between the deteriorated DAG-OIL and TAG-OIL, although
volatile aldehyde emissions increased with frying time. In addition, the acrylamide contents in potato chips prepared with
RS–DAG or RS–TAG were at comparable levels.
A compound identified from air-entrained volatiles produced by adult female Geocoris punctipes attracted male bugs and stimulated males to investigate nearby moving objects of the appropriate size in their search for females. The compound was identified as (E)-2-octenyl acetate, a relatively common component of the volatile semiochemicals produced by a number of heteropteran species. This compound comprised a significant proportion of the female volatiles, whereas it was detected in only trace amounts in volatiles collected from live males. Other components in the extracts from adults of both sexes included (E)-2-hexenyl acetate, (E)-2-octenal, and several saturated hydrocarbons, but these components were not part of the attractant. These compounds plus (E)-2-hexenal, (E)-4-oxo-2-hexenal, and (E)-2-decenal were found in extracts of homogenized adults, whereas the cast skins from late instar nymphs contained (E)-2-octenal, (E)-4-oxo-2-octenal, (E)-2-octenoic acid, and several saturated hydrocarbons.
Pure trilinolein and mixtures of trilinolein-tristearin, trilinolein-triolein, and trilinolein-triolein-tristearin were heated
to 192 C in air. Volatiles were collected, separated, and identified by gas chromatography-mass spectrometry. Major volatiles
observed from each heated sample produced compounds unique to the autoxidation-decomposition of the trilinolein component
and included: pentane, acrolein, pentanal, 1-pentanol, hexanal, 2- and/or 3-hexenal, 2-heptenal, 2-octenal, 2,4-decadienal,
and 4,5-epoxydec-2-enal. When samples containing both trilinolein and triolein were heated, volatiles were produced that could
be ascribed to each triglyceride. However, heated mixtures containing tristearin produced no observable volatiles that could
be related to the oxidized saturated triglyceride. Minor volatiles identified from the heated trilinolein and its mixtures
included; aliphatic acids, saturated and unsaturated aldehydes, primary and secondary alcohols, gamma lactones, furans, hydrocarbons,
and methyl ketones.
To clarify the sources of undesirable flavors, pure hydroperoxides from autoxidized and photosensitized oxidized fatty esters
were thermally decomposed in the injector port of a gas chromatograph-mass spectrometer system. Major volatile products were
identified from the hydroperoxides of methyl oleate, linoleate and linolenate. Although the hydroperoxides from autoxidized
esters are isomerically different in position and concentration than those from photosensitized oxidized esters, the same
major volatile products were formed but in different relative amounts. Distinguishing volatiles were, however, produced from
each type of hydroperoxide. The 9- and 10-hydroperoxides of photosensitized oxidized methyl oleate were thermally isomerized
in the injector port into a mixture of 8-, 9-, 10- and 11-hydroperoxides similar to that of autoxidized methyl oleate. Under
the same conditions, the hydroperoxides from autoxidized linoleate and linolenate did not undergo significant interconversion
with those from the corresponding photosensitized oxidized esters. The compositions of the major volatile decomposition products
are explained by the classical scheme involving carboncarbon scission on either side of alkoxy radical intermediates. Secondary
reactions of hydroperoxides are also postulated, and the hydroperoxy cyclic peroxides from methyl linoleate (photosensitized
oxidized) and methyl linolenate (both autoxidized and photosensitized oxidized) are suggested as important precursors of volatiles.
The influence of oil composition in the main components and of heating time at frying temperature on the formation of toxic alkylated monoaromatic hydrocarbons in oils is studied. Oils of very different compositions such as extra virgin olive, sunflower and virgin linseed oils were submitted to frying temperature in an industrial fryer for prolonged periods of time and the components of their headspace were periodically extracted by solid phase microextraction and studied by gas chromatography mass spectrometry; simultaneously, the formation of polar compounds was also monitored by means of dielectric constant measures. The results obtained evidence the formation of a very high number of alkylbenzenes with molecular weights ranging from 92 to 190. Evolution, during heating time, of the concentration of these compounds in the headspace of the three oils is reported for the first time. Taking these data into account, the ability of these oils to generate these kinds of compounds is evaluated. The formation of unsaturated alkylbenzenes in edible oils during heating at frying temperature is reported for the first time. Relationships between the nature and concentration of alkylbenzenes found and composition in the main components of the original oils are commented on. Significant increases in the concentrations of these toxic compounds in some of the oils studied, occurring before the oil reaches its permitted limit in polar compounds, suggests the advisability of analysing the safety of this limit, in order to protect public health.
The study of the volatile components presents in the headspace of 27 sunflower oil samples, stored over different periods of time, at room temperature in closed receptacles, in presence of limited amounts of air, has been carried out by solid phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS). The composition of the headspace of the studied samples is highly varied, ranging from the characteristic of non-oxidized oils to that of oils with a high oxidation level. Among the detected compounds are alkanals, (E)-2-alkenals, 2,4-alkadienals, ketones, acids, esters, alcohols, as well as aliphatic and aromatic hydrocarbons. In samples having a certain oxidation degree it is worth noting the presence of a significant number of genotoxic and cytotoxic oxygenated α,β−unsaturated aldehydes (OαβUΑs), such as 4-hydroxy-2-nonenal, 4-oxo-2-nonenal or 4,5-epoxy-2-decenal, which have been considered responsible for various degenerative diseases which are widespread nowadays; some of these compounds are described in this manuscript for the first time as coming from edible oil oxidation at room temperature. In addition, it has been found the occurrence of polycyclic aromatic hydrocarbons (PAHs) in concentrations in line with the oxidation level of the sample.
The volatile components of virgin and refined oils whose compositions were very different in terms of oleic, linoleic and linolenic acyl groups were studied by solid phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS), and their composition of acyl groups was determined by proton nuclear magnetic resonance (1) H NMR. The virgin oils studied were olive, linseed and walnut oils, while the refined oils were sunflower and rapeseed oils.
Large differences were found among the headspace compositions of the virgin oils. These were due in part to compounds that could be considered as markers of different vegetable origins and manufacturing processes, but also to compounds resulting from degradative oxidation of the main acyl group components. By virtue of their being refined, fewer components were present in the refined oils, although differences in their headspaces were found owing to the presence of compounds resulting from oxidation of the determined acyl groups.
The studied oils show specific characteristics regarding not only their main components, which are well known, but also their volatile components. The latter provide information on some of the processes to which oils have been submitted, on their oxidation level, on their botanical origin and on the compounds responsible for their odour.
Alzheimer disease elevates lipid peroxidation in the brain and data indicate that the resulting lipid-aldehydes are pathological effectors of lipid peroxidation. The disposition of 4-substituted nonenals derived from arachidonate (20:4, n-6) and linoleate (18:2, n-6) oxidation is modulated by their protein adduction targets, their metabolism, and the nature of the 4-substitutent. Trans-4-oxo-2-nonenal (4-ONE) has a higher toxicity in some systems than the more commonly studied trans-4-hydroxy-2-nonenal (HNE). In this work, we performed a structure-function analysis of 4-hydroxy/oxoalkenal upon mitochondrial endpoints. We tested the hypotheses that 4-ONE, owing to a highly reactive nature, is more toxic than HNE and that HNE toxicity is enantioselective. We chose to study freshly isolated brain mitochondria because of the role of mitochondrial dysfunction in neurodegenerative disorders. Whereas there was little effect related to HNE chirality, our data indicate that in the mitochondrial environment, the order of toxic potency under most conditions was 4-ONE>HNE. 4-ONE uncoupled mitochondrial respiration at a concentration of 5μM and inhibited aldehyde dehydrogenase 2 (ALDH2) activity with an IC(50) of approximately 0.5μM. The efficacy of altering mitochondrial endpoints was ALDH2 inhibition>respiration=mitochondrial swelling=ALDH5A inhibition>GSH depletion. Thiol-based alkenal scavengers, but not amine-based scavengers, were effective in blocking the effects of 4-ONE upon respiration. Quantum mechanical calculations provided insights into the basis for the elevated reactivity of 4-ONE>HNE. Our data demonstrate that 4-ONE is a potent effector of lipid peroxidation in the mitochondrial environment.
In this study it was proved the formation of oxygenated alpha,beta-unsaturated aldehydes (OαβUAs) of 6, 7, 9 and 10 carbon atoms during the thermal treatment (190°C with aeration) of a commercial vegetable oil rich in omega-3 and omega-6 acyl groups, which also contained small amounts of added proteins and carbohydrates to produce barbecue aroma when heated. The OαβUAs detected by Solid Phase Microextraction (SPME) followed by Gas Chromatography/Mass Spectrometry (GC/MS) were: 4-hydroxy-2-hexenal, 4-oxo-2-hexenal and 4,5-epoxy-2-heptenals, coming from omega-3 acyl groups; and 4-hydroxy-2-nonenal, 4-oxo-2-nonenal and 4,5-epoxy-2-decenals, coming from omega-6 acyl groups. Mixtures of this oil, either thermodegraded or not, with standard food were submitted to an in vitro digestion model. The study of the digestion products obtained revealed that OαβUAs remained unaltered, being bioaccessible in the gastrointestinal tract and so able to reach the systemic circulation. Besides, it was evidenced that during digestion Maillard, esterification and oxidation reactions take place.
To clarify the sources of undesirable flavors, pure hydroperoxides from autoxidized and photosensitized oxidized fatty esters
were thermally decomposed in the injector port of a gas chromatograph-mass spectrometer system. Major volatile products were
identified from the hydroperoxides of methyl oleate, linoleate and linolenate. Although the hydroperoxides from autoxidized
esters are isomerically different in position and concentration than those from photosensitized oxidized esters, the same
major volatile products were formed but in different relative amounts. Distinguishing volatiles were, however, produced from
each type of hydroperoxide. The 9- and 10-hydroperoxides of photosensitized oxidized methyl oleate were thermally isomerized
in the injector port into a mixture of 8-, 9-, 10- and 11-hydroperoxides similar to that of autoxidized methyl oleate. Under
the same conditions, the hydroperoxides from autoxidized linoleate and linolenate did not undergo significant interconversion
with those from the corresponding photosensitized oxidized esters. The compositions of the major volatile decomposition products
are explained by the classical scheme involving carboncarbon scission on either side of alkoxy radical intermediates. Secondary
reactions of hydroperoxides are also postulated, and the hydroperoxy cyclic peroxides from methyl linoleate (photosensitized
oxidized) and methyl linolenate (both autoxidized and photosensitized oxidized) are suggested as important precursors of volatiles.