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Abstract

The effect of heating at 180 °C on the antioxidant activity of virgin olive oil (VOO), refined olive oil (ROO) and other vegetable oil samples (sunflower, soybean, cottonseed oils, and a commercial blend specially produced for frying) was determined by measuring the radical-scavenging activity (RSA) toward 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•). The RSA of the soluble (polar) and insoluble (non-polar) in methanol/water fractions of olive oil samples was also measured. The stability of heated oils was assessed by determining their total polar compound (TPC) content. VOO was the most thermostable oil. Total polar phenol content and the RSA of VOO heated for 2.5 h decreased by up to 70 and 78%, respectively, of their initial values; an up to 84% reduction in RSA of VOO polar and non-polar fractions also occurred. Similar changes were observed in the RSA of ROO and its non-polar fraction after 2.5 h of heating. The other oils retained their RSA to a relatively high extent (up to 40%) after 10 h of heating, but in the meantime they reached the rejection point (25–27% TPC). The results demonstrate that VOO has a remarkable thermal stability, but when a healthful effect is expected from the presence of phenolic compounds, heating has to be restricted as much as possible.

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... The colorimetric approach described by Kalantzakis et al. [16] was used to assess the total polyphenolic content (TPC). In summary, the materials were dissolved in n-hexane (Sigma, Germany) and subjected to extraction using a methanol/water combination (60:40, vol/vol). ...
... There was no significant difference between the four olive cultivars regarding SFA, ranging from 12.95% (Nisiot) to 16 ...
... Following the colorimetric method Folin-Ciocalteau, a quantitative analysis of the phenolic compounds in olive oil was carried out [16]. Depending on many factors, including climate, extraction process [33], degree of maturity [26], and cultivar [34], the amount of phenolic compounds found in olive oil can range anywhere from fifty to one thousand milligrams per kilogram for olive oil. ...
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One of the evergreen plants in the Mediterranean environment is the olive tree. Situated in the Northern Mediterranean, Albania possesses a significant proportion of arable land planted by this tree. Olive trees are grown in the western and southern portions of the country, alongside the Ionian and Adriatic Seas, characterized by a Mediterranean climate. Twenty-two native olive cultivars have been classified via their genetic profile. The potential of olive oil production using native cultivars as the primary source gives the country a significant opportunity to distinguish its olive oils (OO). Among them, Kalinjot and Nisiot, two unique native cultivars grown mostly in southern regions, present significant promise. Their OO chemical characterization is distinguished when compared with two other native cultivars, Ulli i bardhë Tirana (Bianco di Tirana) and Mixan, domesticated in central regions. Regarding fatty acid profiles, there is a significant difference in oleic acid, with Nisiot (80.07 ± 0.04%) higher than Mixan OO (71.91 ± 0.06%). On the other hand, variations in Linoleic acid showed higher differences among two cultivars from the same region, Nisiot (4.10 ± 0.00%) and Kalinjot (10.11 ± 0.01%). The phenolic compounds content in OO show that Ulli i bardhë Tirana cv, referring to Gallic acid equivalent (GAE), is 445.03±16.83 mg GAE/kg, is higher compared to the two cultivars, Kalinjot (216.63±10.76 mg gallic acid/kg) and Nisiot (275.45± 11.63 mg GAE/kg). The latest trends in olive cultivation toward international olive cultivars present an essential and delicate situation for the future of indigenous cultivars, both to preserve the genetic diversity, as well as nutritional and organoleptic characteristics of Albanian OO. Globalization has influenced olive cultivation by exposing indigenous olive cultivars to distinguished cultivars worldwide. Promoting the OO from indigenous olive cultivars needs more profound research to enable and highlight the advantages and disadvantages of persisting the tradition of indigenous olive cultivars cultivation.
... Then, the absorbance was again measured (abs t6). The radical scavenging activity was calculated as % of inhibition [47]. The radical scavenging activity (% of inhibition) was plotted against a Trolox calibration curve and results were then expressed as TEAC values (µmol TE·100 g −1 of fat extracted). ...
... The radical scavenging activity (% of inhibition) was plotted against a Trolox calibration curve and results were then expressed as TEAC values (µmol TE·100 g −1 of fat extracted). The antioxidant capacity was determined following the method proposed by Kalantzakis et al. [47] and the following modifications were applied. ...
... Then, the absorbance was again measured (abs t5). The radical scavenging activity was calculated as % of inhibition [47]. The radical scavenging activity (% of inhibition) was plotted against a Trolox calibration curve and results were then expressed as TEAC values (µmol TE·100 g −1 of fat extracted). ...
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In this work, we compared breadsticks (known as Treccine) flavoured with onions and olives and prepared with olive pomace oil (OPO) or with extra virgin olive oil (EVOO). The effect on one-year shelf life was also studied. The following physical, chemical and sensory analyses were conducted on the breadsticks: water activity, moisture content, colour, texture and sensory analysis (appearance, colour, flavour, taste, texture and overall acceptability). For the oil extracted from the Treccine, we determined acidity, peroxide value, spectrophotometric parameters, ABTS and DPPH assay on the hydrolitic fraction, DPPH on the lipid fraction, and fatty acids. We detected a progressive deterioration in the quality of breadsticks with a decrease in shelf life after 4–6 months in relation to each studied parameter. In the analysed breadsticks, water activity was 0.342 (OPO recipe) and 0.387 (EVOO recipe) after one-year storage; in the same storage period, the moisture content was 6.34 times (OPO) and 5.32 times (EVOO) greater. Appearance and colour were the only two sensory parameters which, after 12 months, remained above or equal to five stated as the minimum quality value. In the extracted oil, Free acidity increased from 0.35 to 0.56% (OPO) and from 0.71 to 0.98% (EVOO); Peroxide value ranged between 6.10 and 102.89 meq/kg oil (OPO) and between 4.41 and 20.91 meq/kg oil (EVOO). K232 was highest in OPO (2.43–3.70) and lowest in EVOO (1.76–2.92), K268 was 1.32–1.580 (OPO recipe) and 0.570–0.640 (EVOO recipe). Treccine prepared with extra virgin olive oil showed better biological properties and longer shelf life.
... Moreover, RSA and polyphenols of VOO deep-fried for 2.5 h reduced approximately up to (70 % and 78 %), respectively, however, maintained its thermal stability for long time. The findings reveal that VOO has notable thermal stability (Kalantzakis et al., 2006). ...
... Total polar phenols were decreased from 162 to 72 (mg caffeic acid/kg oil) at 0 and 2.5 h from frying process respectively, the fried virgin olive oil presented stability against thermal stress. (Kalantzakis et al., 2006) OPO Sterols. Anti-inflammation properties and prompt positive impact on cardiovascular health. ...
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Foods fried in olive oil received great attention due to its bioactive profile, antioxidants, high stability, and health benefits. However, several chemical alterations contribute to olive oil degradation during deep-frying (Dsingle bondF), and negatively modify its safety and quality. Therefore, measuring the quality indices of olive oil is a vital topic. The classical chemical approaches are destructive and use toxic chemicals, thus, a harmless and real-time analytical technique has become increasingly critical. This review highlights the recent advances of spectroscopic technologies (STs) stand-alone or integrated with chemometrics to provide reliable, rapid, low-cost, sustainable, multi-parametric, and eco-friendly method for monitoring the quality and safety of olive oil during thermal processing, moreover, the limitations of STs are included. The present review offers fundamental insights regarding the degradation of deep-fried olive oil and provides recent evidence in spectroscopy that can be used as consistent method, providing more benefits for the consumers and food industry.
... Phenolic compounds are extracted using the method described by Kalantzakis et al., (2006) for colorimetric determination of O-diphenols and antiradical activity. Five grams of olive oil were dissolved in 10 mL n-hexane to remove oil, extracted with 10 mL of a methanol: water mixture (60:40, v/v) and then shaken vigorously using a vortex and centrifuged at 3,500 rpm for 10 min. ...
... The hydromethanolic phase was collected. These extracts were used to analyze o-diphenol and DPPH · according to the method of Kalantzakis et al., (2006). O-diphenols were measured colorimetrically at 370 nm after adding 5% (w/v) sodium molybdate in suitable aliquots of the hydromethanolic extract. ...
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Ayvalik is an important and widely grown olive cultivar in Turkey. Olive fruits were harvested at two different harvesting periods, early and middle. Olive oils were extracted in an industrial two-phase continuous system with/without olive leaves at 2%, 4%, and 6% (w/w) concentrations. Oils were stored at room temperature and 12 °C in darkness. Basic quality parameters such as free fatty acids (FFA), peroxide value and absorbance values (K232 and K270) conformed to the European extra virgin olive oil standards. Besides, the fatty acid composition of samples was consistent with the values for extra virgin olive oil reported by the European Commission. Leaf addition enriched phenolic compounds, antiradical activity, oxidative stability, color parameters, and sensory characteristics of Ayvalik olive oils. During storage, the losses in phenolic compounds, color and sensory properties of the oils enriched by adding leaves were less than in the control sample. The sensory properties and phenolic composition of the cold-stored olive oils differed from those stored in the dark and at room conditions. Regarding positive sensory properties, the oils stored in the cold have less loss in their desired properties than those stored under room conditions. In addition, the breakdown of complex phenolic substances into simple phenolic substances such as tyrosol and hydroxytyrosol was found to be less in the samples stored at cold conditions. It has been shown that hydrolytic and oxidative changes occur less in cold storage.
... Polyphenol extraction from oils was carried out in accordance with a previously described procedure [29], and the Folin-Ciocalteu determination was carried out using a known methodology [30]. A quantity of 1 g of oil was diluted with 2 mL of n-hexane and extracted with 2 mL of a 60% methanol/water combination. ...
... Antiradical activity from oil samples was calculated as previously published [29]. In brief, 5 mL of ethyl acetate was mixed with 0.5 g of oil in a 5 mL volumetric flask. ...
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Prunus avium L. and Prunus spinosa L. are valuable fruit-bearing trees known for their bioactive compounds and medicinal properties. However, limited research exists regarding their kernel oils. This study aimed to compare the chemical composition, quality parameters, and bioactive potential of the kernel oils extracted from Prunus avium L. and Prunus spinosa L. The kernel oils’ fatty acid and tocopherol profiles were characterized, and the presence of bioactive compounds were identified and quantified. Total polyphenol content (TPC) and antioxidant activity (AAC) were also measured, indicating the presence of bioactive compounds in both oils. Additionally, the main quality parameters, including oxidative status, were evaluated. The fatty acid analysis revealed a higher proportion of polyunsaturated fatty acids compared to monounsaturated fatty acids in both kernel oil samples. Linoleic acid (57–64%) and oleic acid (18–29%) were the major fatty acids in both Prunus avium L. and Prunus spinosa L. kernel oils. α-Eleostearic acid (11.87%) was quantified only in Prunus avium kernel oil. Furthermore, the α-, β-, γ-, and δ-tocopherol content were determined, and it was found that both kernel oils contained γ-tocopherol as the major tocopherol (~204–237 mg/Kg). TPC in Prunus avium L. kernel oil was measured at 9.5 mg gallic acid equivalents (GAE)/Kg and recorded as ~316% higher TPC than Prunus spinosa L. kernel oil. However, the recorded AAC were 11.87 and 14.22 μmol Trolox equivalent (TE)/Kg oil, respectively. Both oils recorded low peroxide values (~1.50 mmol H2O2/Kg), and low TBARS value (~0.4 mmol malondialdehyde equivalents, MDAE/Kg oil), but high p-anisidine value (23–32). The results indicated that both Prunus avium L. and Prunus spinosa L. kernel oils exhibited unique chemical compositions.
... r Preparation of poplar and non-polar olive oil fractions The separation of polar and non-polar oil fractions was performed according to procedure described by Kalantzakis et al. [2006]. This involved dissolving 2.5 g of each oil in 5 mL of n-hexane and then extracting it with a mixture of 5 mL of methanol and water (60:40, v/v) using a mechanical shaker (Vortex) to ensure thorough mixing. ...
... r Determination of radical scavenging activity of the extra virgin olive oils The ability of the of EVOO polar and non-polar fractions to scavenge the DPPH radical was determined according to Kalantzakis et al. [2006] by adding 250 µL of each oil fraction in ethyl acetate (10%, w/v) to 1 mL of a freshly prepared DPPH radical solution (10 mM in ethyl acetate) in a 2-mL test tube. The mixture was shaken vigorously for 10 s using a Vortex mixer and allowed to stand in the dark for 30 min until a steady state was reached. ...
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Comprehending the variability in the chemical composition of olive oil from the same olive variety, based on its geographical origin, is essential. This study investigated the chemical composition of Chétoui olive oils from thirteen mills located in Northern Tunisia's Béja region. The chemical composition of olive oil exhibits substantial regional variability. Free acidity ranged from 0.57% to 0.73%, and peroxide values varied between 7.33 and 14.00 meq O2/kg. Total phenolic content varied as well, with values ranging from 906.53 to 1,298.60 caffeic acid eq/kg (oils from Amdoun and Testour II, respectively). Chlorophyll contents ranged from 2.03 to 7.85 mg/kg, and carotenoids from 1.28 to 3.92 mg/kg. Olive oils from Amdoun and Dogga II were the richest in these compounds. In terms of tocopherols, the range extended from 282.88 mg/kg (oil from Tibar) to 416.79 mg/kg (oil from Testour II). DPPH radical scavenging activity of the polar fraction of all olive oils was higher than that of the non-polar fraction. Fatty acid profiles were mostly similar with exception of the oil from Tibar with lower saturated fatty acid content and higher monounsaturated fatty acid content. Substantial differences in polyunsaturated fatty acid content were found. Triacylglycerol compositions differed as well, with the lowest triolein percentage around 13.66% and the highest at approximately 34.98%. In summary, this study reveals significant regional variations in the chemical composition of Chétoui monovarietal olive oil, highlighting the collection region impact on oil quality and nutritional properties.
... Polyphenol extraction from oils was performed according to a previously described protocol [14], and Folin-Ciocalteu determination was executed based on a published methodology [15]. An accurate amount of 1 g of oil was diluted with 2 mL hexane and extracted with 2 mL of 60% methanol/water mixture. ...
... TEAC was estimated as reported elsewhere [14]. In short, 0.5 g of oil was dissolved in 5 mL of ethyl acetate. ...
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The current project aimed at examining the effect of the enrichment of commercial seed oils with waste orange peel (WOP) extracts on their polyphenolic profiles and resistance against oxidation. Polyphenol-containing WOP extracts were produced using a novel combination of ethanol and triacetin, and they were incorporated into seed oils (sunflower, soybean, corn oil), at a level of 36.87 mg per kg of oil. The oils were then stored at 60 • C, for 58 days. By performing a Rancimat test, it was shown that enrichment of sunflower, soybean, and corn oils with WOP extracts did not provoke any prooxidant effects, but, to the contrary, exerted an antioxidant action, with protection factors varying from 1.01 to 1.61. Furthermore, in all cases examined, it was demonstrated that, during the storage period, the stabilizing effect of WOP extract against oxidation was comparable to that observed in oil samples containing 200 mg BHT per kg oil. This outcome was ascertained by measuring the onset of peroxide value, thiobarbituric-acid-reactive substances, and the TOTOX value. Furthermore, it was revealed that the Trolox-equivalent antiradical activity of the enriched oils exhibited a decline at the end of the examination period, a fact most probably attributed to the depletion of the antioxidants occurring in the oils. It was concluded that the method proposed might be a means of stabilizing commercial seed oils against oxidation, and of enhancing their nutritional value by enriching them with natural polyphenols.
... After 12h of deep frying, all oils reach extremely low TEAC values. This comes in accordance with Kalantzakis et al. (2006), where olive oil samples practically lost their radical scavenging activity after 5 h of heating at 180 oC [35]. Although, oil samples are not expected to present any radical scavenging activity at the end of the frying experiment, the TEAC values are elevated for all samples ( Figure S1a). ...
... After 12h of deep frying, all oils reach extremely low TEAC values. This comes in accordance with Kalantzakis et al. (2006), where olive oil samples practically lost their radical scavenging activity after 5 h of heating at 180 oC [35]. Although, oil samples are not expected to present any radical scavenging activity at the end of the frying experiment, the TEAC values are elevated for all samples ( Figure S1a). ...
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Fresh potatoes were deep-fried in olive oil (OO) & extra virgin olive oil (EVOO) and their blends with 5%, 10% and 20% v/v sesame oil (SO). This is the first report on the use of sesame oil as natural source of antioxidant for olive oil deep-frying. Oil was evaluated for Peroxide Value (PV), Free Fatty Acids (FFA), K232, K270, Trolox Equivalent Antioxidant Capacity (TEAC) and Total Phenols (TP) until Total Polar Compounds (TPCs) reached 25%. Sesame lignan transformations were monitored through Reverse-phase HPLC. While TPCs in olive oils increased at a steady rate, the addition of 5%, 10% and 20% v/v SO created a time window lasting 1, 2 and 3 hours, respectively, where TPCs were constant. SO addition to OO increased the total frying time. Furthermore, the addition of SO reduced the peroxides formation rate for both OO and EVOO. EVOO was more resistant to oxidation than OO as measured by TPCs and TEAC, while frying time raised from 21.5 to 25.25 h when EVOO replaced OO. The increase in frying time for olive oil but not for extra virgin olive oil, after SO addition, is pointing out a niche market for extra virgin olive oil in deep-frying.
... Antioxidant activity is another important quality parameter of edible oil. The method of measuring the scavenging free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) was normally used to determine the antioxidant activity of oil (Kalantzakis et al., 2006). Oil extraction from plant seed can be conducted by using different solvent polarities (polar and non-polar solvents). ...
... At the same time, the antioxidant activity of other chia seed oils also declined sharply with the value of 40.70% to 1.96% (A8-40) and 32.53% to 3.36% (H8-40). The antioxidant activity of chia seed oils dropped markedly (p < 0.05) when exposed to a higher temperature (40°C).This could be attributed to oils with a high content of PUFA deteriorated after exposing to accelerated temperature and the concentration of antioxidant compounds present (Kalantzakis et al., 2006). According to Alothman et al. (2009), the effectiveness of antioxidant depends on the high polarity of the solvent. ...
Article
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This study consists of two parts. The first part is to identify the fatty acid composition of chia seed oils obtained by Soxhlet method using acetone and hexane as extraction solvents with different extraction times including acetone 4 hrs (A4), acetone 8 hrs (A8) and hexane 8 hrs (H8) as a control. Next, the oxidative stability and antioxidant activity of chia seed oils stored at different temperatures (25°C and 40°C) for 18 days were evaluated. From the study, chia seed oil (A8) had the highest content of α-linolenic acid (67.79%) with significant difference (p < 0.05) followed by other oil samples that were extracted using acetone and hexane for 4 hrs (67.54%) and 8 hrs (66.38%), respectively. The oxidative stability of chia seed oil was determined by peroxide value, p-anisidine value and TOTOX value. The results revealed that chia seed oils stored at room temperature (25°C) had higher oxidative stability compared to oil samples stored at 40°C. Elevated temperature strongly affected lipid oxidation. The control sample had higher oxidative stability than acetone-extracted chia seed oils. Meanwhile, antioxidant activity using DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity test was also carried out. Antioxidant activity of chia seed oil extracted by acetone had higher radical scavenging activity inhibition (p < 0.05) than the control sample at both temperatures (25°C and 40°C).The results confirmed that chia seed oil obtained by acetone had higher polyunsaturated fatty acids and lower oxidative stability than hexane. In conclusion, chia seed oil extracted by hexane showed better oxidative stability at different storage temperatures.
... The fractionation of the oil samples was performed according to the method described by Kalantzakis et al. (2006). Unheated and heated VOO samples (2.5 g) were dissolved in 5 mL of n-hexane and extracted with 5 ml of a methanolwater mixture (60:40, v/v). ...
... VOO samples were analyzed for their capacity to scavenge the stable 1,1-diphenyl-2-picrylhydrazyl radical [DPPH Å ] ( Kalantzakis et al., 2006). One mL of the oil solution in ethyl acetate (10%, w/v) was added to 4 mL of a freshly prepared DPPH Å solution (10 -4 M in ethyl acetate) in a screw-cap 10 mL test tube. ...
... The inhibition of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH • ) was measured with an established method from Kalantzakis et al. [16] with some modifications, since the authors used 1 mL of 10% w/v diluted oil and 4 mL of freshly prepared 100 µM DPPH • solution in ethyl acetate. In brief, a volume of 950 µL of DPPH • solution (100 µM in ethyl acetate) was mixed with 50 µL of a 10-fold diluted oil sample. ...
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Recently, there has been a significant transition in the dietary preferences of consumers toward foods containing health-promoting compounds. In addition, as people’s environmental awareness increases, they are increasingly looking for sustainable solutions. Palm oil, an oil used extensively by the food industry, does not fit these criteria. This study investigated the development of a complex oil blend consisting of commonly used vegetable oils such as corn, rapeseed, sunflower, and palm oil. The aim was to find the optimal blended oil and compare this combination with palm oil in terms of its oxidative stability, antioxidant capacity, and the composition of bioactive compounds (i.e., fatty acids, tocopherols, and carotenoids). Palm oil was found to have greater oxidative stability as a result of its increased concentration of saturated fatty acids. The optimal blended oil, which consisted of corn and rapeseed oil at a ratio of 4:3 w/w, inhibited the superior antioxidant activity, showing a ~33% increase in DPPH• inhibition activity. ATR-FTIR spectra further verified the existence of a significant quantity of saturated fatty acids in palm oil and unsaturated fatty acids in the blended oil. Finally, several correlation analyses revealed interesting connections between oil samples and investigated parameters. This work has the potential to establish a basis for the mass production of oil blends that possess high concentrations of antioxidant compounds and reduce the use of palm oil.
... For the determination of the TPC of the oil samples, a previously described method was followed [34]. ...
Article
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Edible blossoms and extracted oils from various parts of plants have gained the interest of researchers in recent years due to their strong antioxidant activity and their high content of vitamins. In addition, they contain a plethora of polyphenols, and they do not have high caloric content. The blossoms of Prunus dulcis (i.e., almond tree) are edible; however, they have not been examined in terms of nutritional value. The present study aimed to examine the nutritional value of almond blossoms, as well as their extracted oil. The fat content of the blossoms was 1.75 g/100 g dry weight (dw), while the defatted blossoms were found to contain 1.34 g/100 g dw of crude protein and 29.97 g/100 g dw of carbohydrates. In addition, the blossom oil was tested for its composition of fatty acids, polyphenols, and total carotenoids. According to the results, several important fatty acids for human health were identified, such as oleic (25.17%), linoleic (15.64%), and linolenic (10.15%). Simultaneously, a low oxidation index (COX), i.e., 4.05, and many monounsaturated (25.17%) and unsaturated (67.56%) fats were detected, while both polyphenols (51.86 mg GAE/kg) and carotenoids were in abundance. Finally, the combination of simple stirring with ultrasound (a green extraction method) was found to be the most appropriate method to ensure maximum amounts of various antioxidant compounds in the blossom extracts (i.e., polyphenols and L-ascorbic acid). After optimization, the total polyphenol content increased by 23.98% and L-ascorbic acid content by 6.96%. In addition, antioxidant activity was tested by different antioxidant assays and specifically FRAP, DPPH, and H2O2, which showed a corresponding increase (14.46, 17.23, and 8.79%, respectively). Therefore, it can be concluded that Prunus dulcis blossoms, besides being edible, are also highly nutritious, and their oil has nutritional value and deserves further exploration.
... The hexane layer was discarded, and the resulting extract was used for antioxidant analysis. Antioxidant assays 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (RSC), expressed as % inhibition, and total phenolic content (TPC), expressed as mg gallic acid equivalent per g (mg/g), were carried out according to Kalantzakis et al. (2006). ...
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Nigella sativa, commonly known as the black seed, is a culinary spice therapeutic against many ailments. Common preparation practice of roasting or heating the seeds often deteriorates bioactive compounds, which can be remedied with superheated steam (SHS). With roasting temperatures of 150, 200, and 250°C and roasting times of 10, 15, and 20 min, convection and SHS roasting media were tested, and their effects on proximate analysis, antioxidant assays, and oil quality were evaluated. For proximate content, moisture significantly decreased from 9.08% in unroasted seeds to 4.18%-1.04% in roasted seeds, while fat increased to as high as 44.76% from 32.87% in unroasted seeds. Roasting only slightly increased ash content and had no significant impact on protein and carbohydrate content. SHS roasted black seeds had better DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging capacity (RSC) than convec-tion roasted seeds. DPPH RSC decreased with elevated roasting time and temperature , conversely related to total phenolic content, which increased with increased roasting time and temperature. Oil of roasted seeds developed an increasingly intense brown color from an initial light, yellow, unroasted oil with better extraction efficiency in SHS roasting. For oil quality analysis, free fatty acid values were significantly lower in both roasted samples. Peroxide value was initially recorded at 84 in convection and 48 (meq O 2 /kg of oil) in SHS roasted samples. In contrast, p-anisidine values were initially recorded at 28.36 in convection roasted samples compared to 23.73 in SHS roasted samples. Based on all quality analyses, SHS showed better potential in black seed quality preservation.
... Studies were carried out to determine the antioxidant activity in macaúba pulp oil by scavenging the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ORAC (oxygen radical absorbance capacity), showing values of 23.89 µg mL −1 and 42.02 µM TE/g fresh mass, respectively [4,31,32]. ...
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This study discusses the bioactive composition, supercritical extraction, and biological activity of Acrocomia aculeata in publications in the last ten years. Numerous compounds have been identified in A. aculeata, which include fatty acids, carotenoids, phenolic compounds, and tocopherols, discussed in this article. Although there are several studies with the fruit using conventional extraction to obtain oil, there are only a few involving extraction at high pressures. Therefore, this article emphasized the potential of extraction with supercritical fluid (SFC) to obtain oil due to its good selectivity, fractions distributed in terms of mass yield, and chemical composition of the obtained extracts, which provides a solvent-free product, making it safe for application in the food industry. The biological activity of A. aculeata extracts was also discussed, including antidiabetic, anti-inflammatory, diuretic, antimicrobial, antioxidant, neuroprotective, and photoprotective effects, which can produce effects on human health. This review produces important results that can act as a basis for future studies related to obtaining bioactive compounds from A. aculeata with a high degree of purity and good quality in its applications.
... In our study, the total antioxidant capacity was expressed as the Trolox equivalent antioxidant capacity (TEAC), defined as the mmol Trolox/kg of oil. The OO blends with SO initially had higher TEAC values than OO, which were proportional to the percentage of SO in the blend ( [32]. Although the oil samples were not expected to present any radical scavenging activity at the end of the frying experiment, the TEAC values were elevated for all samples ( Figure S1a). ...
Article
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Fresh potatoes were deep-fried in olive oil (OO), extra virgin olive oil (EVOO), and their blends with 5%, 10%, and 20% v/v sesame oil (SO). This is the first report on the use of sesame oil as a natural source of antioxidants during olive oil deep frying. The oil was evaluated for anisidine value (AV), free fatty acids (FFAs), extinction coefficient (K232 and K270), Trolox equivalent antioxidant capacity (TEAC), and total phenols (TPs) until the total polar compounds (TPCs) reached 25%. Sesame lignan transformations were monitored through reversed-phase HPLC. While the TPCs in olive oils increased at a steady rate, the addition of 5%, 10%, and 20% v/v SO delayed TPCs' formation for 1, 2, and 3 h, respectively. The addition of 5%, 10%, and 20% v/v SO increased the olive oil frying time by 1.5 h, 3.5 h, and 2.5 h, respectively. The addition of SO to OO reduced the secondary oxidation products' formation rate. The AV for EVOO was lower than OO and all tested blends, even those with EVOO. EVOO was more resistant to oxidation than OO, as measured by the TPCs and TEAC, while the frying time rose from 21.5 to 25.25 h when EVOO replaced OO. The increase in frying time for OO but not for EVOO, after SO addition, points to a niche market for EVOO in deep frying.
... The DPPH antioxidant assay was performed according to an established method [68], modified as follows: LSBE was diluted with ethyl acetate (1:10, v/v), then 2 mL of a 10 −4 M DPPH• stock solution previously prepared with ethyl acetate was added to 500 µL of diluted LSBE. An absorbance at 515 nm was read immediately after the addition of the (T0) and after 30 min of incubation (T30). ...
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In women, breast cancer is the most commonly diagnosed cancer (11.7% of total cases) and the leading cause of cancer death (6.9%) worldwide. Bioactive dietary components such as Sea buckthorn berries are known for their high carotenoid content, which has been shown to possess anti-cancer properties. Considering the limited number of studies investigating the bioactive properties of carotenoids in breast cancer, the aim of this study was to investigate the antiproliferative, antioxidant, and proapoptotic properties of saponified lipophilic Sea buckthorn berries extract (LSBE) in two breast cancer cell lines with different phenotypes: T47D (ER+, PR+, HER2−) and BT-549 (ER-, PR-, HER2−). The antiproliferative effects of LSBE were evaluated by an Alamar Blue assay, the extra-cellular antioxidant capacity was evaluated through DPPH, ABTS, and FRAP assays, the intracellular antioxidant capacity was evaluated through a DCFDA assay, and the apoptosis rate was assessed by flow cytometry. LSBE inhibited the proliferation of breast cancer cells in a concentration-dependent manner, with a mean IC 50 of 16 µM. LSBE has proven to be a good antioxidant both at the intracellular level, due to its ability to significantly decrease the ROS levels in both cell lines (p = 0.0279 for T47D, and p = 0.0188 for BT-549), and at the extracellular level, where the ABTS and DPPH inhibition vried between 3.38-56.8%, respectively 5.68-68.65%, and 35.6 mg/L equivalent ascorbic acid/g LSBE were recorded. Based on the results from the antioxidant assays, LSBE was found to have good antioxidant activity due to its rich carotenoid content. The flow cytometry results revealed that LSBE treatment induced significant alterations in late-stage apoptotic cells represented by 80.29% of T47D cells (p = 0.0119), and 40.6% of BT-549 cells (p = 0.0137). Considering the antiproliferative, antioxidant, and proapoptotic properties of the carotenoids from LSBE on breast cancer cells, further studies should investigate whether these bioactive dietary compounds could be used as nutraceuticals in breast cancer therapy.
... The extraction of water-soluble components from the AKO samples was carried out according to a modified method previously described [16]. 1 g of AKO sample was diluted with 2 mL of n-hexane, and water-soluble components were extracted with 2 mL of a 60:40 (v/v) methanol/water solution. After vortexing for 2 min, the mixture was centrifuged at 4500 rpm for 5 min. ...
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Apricot kernels are known to be rich in bioactive compounds such as polyphenols, which have applications in various fields such as cosmetology and the food industry. However, the extraction of these compounds has not been extensively studied. In this study, we aimed to extract oil from apricot kernels and investigate its composition and antioxidant properties. Samples from two years of apricot cannery by-products were used in the study. We employed a common extraction procedure using hexane as a solvent, followed by an analysis of the oil’s fatty acid composition and determination of its antioxidant properties using several methods. Our results indicated that the oil extracted from apricot kernels is rich in oleic and palmitoleic acids, which exhibit health benefits. As regards the volatile compounds of the oil, 2-methyl propanal, benzaldehyde, and benzyl alcohol were detected as the main compounds. Benzaldehyde was also found to be the main component of the essential oil of the kernel. Furthermore, the oil exhibited low antioxidant activity, as demonstrated by its ability to scavenge free radicals. Overall, our findings suggest that apricot kernels are a valuable source of oil with potential applications in the food and cosmetic industries.
... The extraction of polyphenols from the olive oils was performed as described by Kalantzakis et al. [21]. Olive oil samples (1 g) were dissolved in 2 mL of n-hexane and 2 mL of a 60:40 (v/v) methanol/water solution. ...
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The extraction of olive oil produces significant residual olive-mill wastewater (OMW). The composition of OMW varies according to the type of olive, the fruit’s ripeness level, and the extraction method (traditional one-pressing system or continuous systems based on centrifugation of the olive pulp). In olive-producing countries, OMW is important for the environment and the economy and is also a low-cost source of polyphenolic compounds with high antioxidant properties. Olive oil’s properties, such as its anti-atherogenic, anti-inflammatory, anti-aging, and immunological modulator effects, have been attributed to its polyphenols. In this study, the cloud point extraction (CPE) method was used to recover polyphenolic compounds from OMW. The total micellar phase of the three recoveries was 24.2% and the total polyphenols (after sonication) was 504 mg GAE/Kg. Furthermore, the addition of polyphenols recovered from OMW enhanced the olive oil and extended its shelf life without changing its organoleptic properties. There was a 42.2% change in polyphenols after 0.5% enrichment of micellar dispersions. Thus, it is suggested that the CPE method could lead to better waste management in the olive oil industry and improve the nutritional quality of food products.
... The DPPH radical scavenging capacity of cocoa extract samples was assessed using the process of Kalantzakis et al. (2006). At 517 nm, the scavenging effect was measured spectrophotometrically, and the percentage of DPPH radical inhibition was calculated using the equation given as below: ...
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This research focused on the roasting of cocoa beans at 184°C for 16 minutes duration in a superheated steam oven using two separate modes of heating: convection mode and superheated steam mode. After roasting, the antioxidant properties of the cooked cocoa were assessed as ferric reducing antioxidant power activity (FRAP), DPPH radical scavenging activity, total flavonoid content (TFC) and total phenol content (TPC). The micro structural properties of raw and processed cocoa beans were observed using scanning electron microscopy (SEM). As discovered in the scan, conventional roasting showed a nearly complete rapture of the cytoplasmic network system and the destruction of the organelles, whereas superheated steam mode showed satisfactory images. Studies indicated that superheated steam roasting preserved significantly (p < 0.05) greater antioxidant properties as opposed to conventional method of roasting.
... Tocopherol samples were analyzed for their capacity to scavenge the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) in accordance with Kalantzakis et al. [39], with some modifications. Briefly, a 25 µL volume of tocopherol sample (in pure form or mixture) was mixed with 975 µL of DPPH solution (100 µM in ethyl acetate) and absorbance was read at 515 nm immediately after mixing (A 515(i) ) and after exactly 30 min (A 515(f) ), using a Shimadzu UV-1700 UV/vis spectrophotometer (Kyoto, Japan). ...
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Tocopherols are natural bioactive compounds with several health benefits. This study evaluated the effect of different ratios of α- and δ- tocopherol homologs to protect sunflower oil (SO) and olive pomace oil (OPO) against oxidation. A synergistic effect was recorded when the two tocopherols were combined at a ratio of 7:1 (α-T/δ-T). The oil samples were exposed to accelerated oxidation conditions using a Rancimat (90 °C and airflow of 15 L/h for 24 h) and protection from tocopherols was compared with that from butylated hydroxytoluene (BHT). Assessment of oil stability was examined using well-known parameters such as peroxide value (PV), thiobarbituric acid reactive substances (TBARS), p-anisidine value (p-AV), conjugated dienes (CD) and trienes (CT), and total oxidation (Totox) value, which were all significantly reduced when tocopherols were added at a ratio of 7:1 α-T/δ-T. Primary oxidative compounds measured according to PV were only reduced in SO samples (6.11%). Off-flavor compounds measured via TBARS assay in SO samples were reduced by above 20%, while p-AV was also reduced. CDvalue was correlated with PV in SO samples, while the 7:1 mixture was more effective than BHT for CTvalue. Total oxidation values in SO samples and OPO samples were reduced by 6.02% and 12.62%, respectively. These values in SO samples also provided a remarkable correlation (R2 > 0.95) with incubation time. Moreover, the synergistic effect was not only effective in reducing the oxidation values of oil samples, but also in lowering the degradation rate of tocopherols. Protective effects from tocopherols were mainly observed in SO samples, as OPO samples were more resistant to oxidation processes. This effect was even observed in fatty acid analysis, where the 7:1 mixture provided better results than BHT-spiked samples. Thus, it is suggested that tocopherol mixtures might be used as a natural preservative in the food industry to restrain lipid oxidation processes.
... The extraction of total polyphenols from olive oil was carried out according to a previous report [28]. Olive oil samples (1 g) were dissolved in 2 mL of n-hexane before being extracted with 2 mL of a 60:40 (v/v) methanol/water solution. ...
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In this study, an alternative debittering technique for olives, invented and patented by Prof. Vassilis Dourtoglou, was employed. Olive fruits (Olea europaea cv. Megaritiki) were stored under CO2 atmosphere immediately after harvest for a period of 15 days. After the treatment, a sensory evaluation between the olives stored under CO2 and those stored under regular atmospheric conditions (control) was performed. Additionally, the CO2-treated olives were used for the cold press of olive oil production. The volatile profile of the olive oil produced was analyzed using headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC-MS). A total of thirty different volatile compounds were detected. The volatile characteristics of olive oil are attributed, among others, to aldehydes, alcohols, esters, hydrocarbons, alkanes, and terpenes. The volatile compounds’ analysis showed many differences between the two treatments. In order to compare the volatile profile, commercial olive oil was also used (produced from olives from the same olive grove with a conventional process in an industrial olive mill). The antioxidant activity, the content of bioactive compounds (polyphenols, α-tocopherol, carotenoids, and chlorophylls), and the fatty acids’ profile were also determined. The results showed that the oil produced from CO2-treated olives contains different volatile components, which bestow a unique flavor and aroma to the oil. Moreover, this oil was found comparable to extra virgin olive oil, according to its physicochemical characteristics. Finally, the enhanced content in antioxidant compounds (i.e., polyphenols) not only rendered the oil more stable against oxidation but also better for human health. The overall quality of the olive oil was enhanced and, as such, this procedure holds great promise for future developments.
... The antioxidant activity of Lepidium sativum seed oil was evaluated through DPPH and ABTS assays. For the DPPH assay, a Lepidium sativum seed oil sample was tested for its scavenging ability against the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals (Kalantzakis et al., 2006). One millilitre of a compound of 0.5 g oil in a 5 mL of ethyl acetate was mixed with 4 mL of a 10 -4 M ethyl acetate DPPH solution within a 10 mL screw cap test tube. ...
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Lepidium sativum is cultivated mainly for the edible oil from its seeds, and considered as an unutilized and neglected crop despite its important properties. Its oil fraction is used to produce soap and stabilize linseed oil when it is mixed with wild mustard seed oil. Once converted into fatty acid methyl esters, it represents a good substitute for imported petroleum diesel after alkaline transesterification reaction. In the current study, Lepidium sativum seeds cultivated in Tunisia and the physicochemical properties and nutrient profile of its cold pressed seed oil were investigated. The antioxidant, antibacterial, and anti-inflammatory activities of the above oil were also assessed. Lepidium sativum seed oil was abundant in both linolenic (35.59 ± 1.9 %) and oleic (21.14 ± 0.63 %) acids, and high amounts of β-sitosterol (42.57 ± 2.96 mg/100g), campesterol (20.04 ± 1.4 mg/100g) and Δ 5,24 stigmastadienol (11.82 ± 0.45 mg/100g) were detected. The total tocopherol content of Lepidium sativum seed oil reached 136.83 ± 7.6 mg/100g with a predominance of γ-tocopherol (86.23 %). Its seed oil exhibited an IC50 of 10.33 ± 0.05 mg/mL and a radical scavenging activity of 415.6 ± 40 Trolox Equivalent Antioxidant Capacity (TEAC) for the DPPH and the ABTS assays, respectively. While the thermal analysis proved a high thermal stability of Lepidium sativum seed oil, that of eight bacteria and one fungal strain showed no noticeable bacterial or antifungal effects. It was also revealed that Lepidium sativum seed oil held a remarkable anti-inflammatory activity. Hence, the obtained results evidenced remarkable chemical, antioxidant and anti-inflammatory properties of Lepidium sativum seed oil, which might potentially be promising for enhancing human health and preventing age-related diseases.
... The determination of % scavenging activity of DPPH radical was according to a modified method described in the literature [32]. Briefly, 1 mL of the oil solution in ethyl acetate (10% w/v) was added to 4 mL of a freshly prepared DPPH solution (10 -4 M in ethyl acetate). ...
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Among the various parameters affecting olive oil quality, ripening stage is one of the most important. Optimal harvest time ensuring target quality for the final product varies in relation to the effect of many intrinsic and extrinsic factors. Therefore, its determination necessitates thorough examination of each case. The present study explores the impact of six harvest times on volatile profile and quality attributes of olive oils from “Chondrolia Chalkidikis” Greek cultivar. All samples examined were classified “Virgin Olive Oils” (VOOs) according to findings of acidity, peroxide, and K values. The low values for the principal official quality indices, the high oleic acid percentages (76–78%), the high oxidative stabilities (up to 36 h induction period), and phenols content (606–290 mg/kg) were considered nutritionally promising. Total phenols, carotenoids and chlorophylls contents, as well as oxidative stability (induction period values) decreased with ripening. Harvest time had a strong impact on HS-SPME–GC–MS volatile fingerprint. Optimal volatile profiles were related to intermediate examined ripening stages. Fatty acid composition did not show remarkable trends. Chondrolia Chalkidikis VOOs perform as interesting candidates of high quality. Findings of the study may support existing databases with scientific records for Chondrolia Chalkidikis VOOs, boost their competitiveness in the global market, and encourage worldwide exploitation of VOOs from similar cultivars (table olives oriented).
... There was a significant decrease (p≤0.05) in antioxidant activity by 11.49% at 140°C (66.15 %) and by 29.64% 180°C (52.58%). Similar findings were reported byKalantzakis et al., 2006 where the DPPH scavenging activity of various vegetable oils decreased during heating at 180°C. The antioxidant activity of oil can be directly related to the amount of phenols present owing to the presence of hydroxyl groups that have the ability to destroy the radicals and form stable phenoxyl radicals(Bajalan et al., 2017), thus rendering free radical scavenging activity. ...
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The effect of heating flaxseed oil at varied temperatures on the TPC (total phenol content), TFC (total flavonoid content) and DPPH (1, 1-diphenyl-2-picrylhydrazyl) radical scavenging activity was evaluated. Oil was heated at varied temperatures of 25ºC, 60ºC, 100ºC, 140ºC, 180ºC for duration of 30 minutes each. Results indicated that TPC increased upto 100°C followed by a decreasing trend at 140°C and 180°C. On the other hand the TFC content decreased dramatically (p≤0.05) upon heating. The DPPH scavenging activity showed more or less similar results upto 100 ºC thereafter decreased at 140 ºC. The result suggests that antioxidative and radical scavenging activity deteriorated on heating the oil at higher temperature (at 140 ºC and above).
... The DPPH assay of the extracted fat was performed without extracting antioxidant compounds from the fat. It was conducted in an UV/Vis Spectrometer λ 2 from Perkin Elmer (Waltham, MA, USA) using the method proposed by Kalantzakis et al. [25], modified as follows. The fat was diluted with ethyl acetate (1/10, v/v). ...
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Olive oil is recognised for its beneficial effects on human health, mainly due to it containing oleic acid (a monounsaturated fatty acid), whereas fats of animal origin or margarine, which are often used in recipes for biscuit production, contain mainly saturated fatty acids. The aim of this study was to evaluate the shelf-life and physicochemical properties of biscuits and of the fats contained in original recipe Italian Cantuccini biscuits (50% cow’s butter and 50% margarine). Additionally, the sensory properties of the biscuits were evaluated, including their colour, appearance, taste, flavour, texture and overall acceptability. At the same time, the fat composition of the original recipe was also modified to contain 30% cow’s butter and 70% extra virgin olive oil, in order to replace an aliquot of the saturated fatty acid content with unsaturated fatty acids, in particular with one monounsaturated fatty acid, oleic acid. Colour (CIELab), water activity, relative humidity, hardness and fracturability analyses were conducted on Cantuccini biscuits. Colour (CIELab), free acidity, spectrophotometric characteristics, DPPH assay and fatty acid methyl ester (FAMEs) analyses were conducted on the fat extracted from Cantuccini biscuits prepared from both the original and modified recipes.
... The DPPH (2,2-diphenyl-1-picryhydrazal) solution was used to assess the DPPH radical scavenging activity of the aqueous extract according to the procedure as described by Kalantzakis et al. [36]. In brief, a DPPH solution was prepared by adding 0.00394 g DPPH in 100 mL 80% methanol, mixed well and kept in a dark place for about 24 hours. ...
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This research was done to optimize the influence of various egg albumin (EA) concentrations of 2, 4, and 6% as a foaming agent and whipping times of 5, 10, and 15 minutes, on physicochemical and antioxidant properties of plum powder produced using response surface methodology (RSM). Physical properties of the foam such as density, porosity, and expansion were determined. After drying and powder manufacturing, physical properties, namely, the water absorption index (WAI) and water solubility index (WSI), as well as chemical characteristics such as pH, titratable acidity, and browning index, were assessed. Finally, antioxidant capabilities such as the total phenol content (TPC), DPPH scavenging activity, beta carotene, and total flavonoid content (TFC) were measured. According to the findings, both whipping duration and EA concentration had a substantial effect on the foam forming characteristics. Foam expansion increased significantly with EA concentration and whipping time increase, but foam density exhibited an inverse relationship as expected. Increases in EA concentration and whipping duration both raised pH values whereas titratable acidity exhibited an inverse tendency as variable quantity rose. The browning index dropped as EA concentration increased. Antioxidant qualities were retained in dried sample powder as compared with the fresh sample, and they were also altered by variable changes. Overall, a 4% EA concentration for 10 to 15 minutes produced the best dehydration effects with the most antioxidant retention.
... The 2-2-diphenyl-1-picrylhidrazil (DPPH) radical scavenging activity of corn germ oils was determined according to Kalantzakis et al. (2006), with minor modifications. Nearly 200 mg of corn germ oil was mixed with 1 mL of methanol and vigorously shaken for 5 min. ...
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The extraction of corn germ oil was evaluated using pressurized propane as solvent in semi-batch process as an alternative approach to organic solvent extraction. The effect of temperature (20, 40, 60 °C), pressure (20, 60, 100 bar), particle size and confinement time were studied. Moreover, the extraction kinetics for the pressurized solvent were determined. Temperature and pressure had no effect on the extraction yield. Consequently, the lowest temperature and pressure involved in this study (20 °C and 20 bar) could be used without implications on yield. An increase in confinement time had a positive effect and the increase of particle size had a negative effect on the yield. The extracted oils were characterized by physicochemical properties, total phenolic content (TPC) and antioxidant activity. In general, pressure exerted a positive effect on these properties for propane-extracted oils, indicating that the pressure may be managed to improve the quality of the extracted oil. The antioxidant activities of propane-extracted oils, which seemed to be correlated with their corresponding TPC value, were closer to those obtained with hexane. For propane extracts, the highest TPC of 29.89 mg GAE/100 g of oil was obtained by extracting wet-milled corn germs at 60 °C and 100 bar. The highest extraction yield with propane was 38.4 ± 1.2 wt% at 20 °C, 20 bar, 30 min and 0.95 mm particle size.
... A capacidade de eliminação do radical DPPH • foi determinada de acordo com Kalantzakis et al. (2006) e o resultado foi expresso em porcentagem. O método baseado na redução do radical ABTS •+ foi realizado conforme metodologia descrita por Re et al. (1999), cujos resultados foram calculados por uma curva padrão obtida pela medida das absorvâncias da solução de trolox (50 μM/L-2000 μM/L), com coeficiente de determinação (R 2 ) de 0,9990. ...
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p class="Normal1"> Este trabalho teve como objetivos caracterizar as sementes de chia ( Salvia hispanica L.), gergelim ( Sesamum indicum L.) e linhaça ( Linum usitassimum L.) quanto à composição centesimal, bem como avaliar as propriedades físico-químicas e capacidade antioxidante dos seus óleos. As sementes apresentaram elevadas quantidades de lipídios (31,3-46,7%) e proteínas (16,6-25,5%). O óleo de chia mostrou maior degradação hidrolítica e oxidativa devido aos índices de acidez (5,27 mg KOH/g), peróxidos (2,76 meq/kg), ρ -anisidina (3,15) e, consequentemente, o valor Totox (8,79). Quanto aos ácidos graxos, os óleos mostraram ser predominantemente constituídos por ácidos graxos insaturados, sobressaindo o de chia com maior quantidade de ácido α-linolênico (58%). Os óleos de gergelim mostraram quantidades consideráveis de tocoferóis totais (2538,10-2645,59 mg/kg). O óleo de gergelim branco mostrou teor significativo de carotenoides totais (128,44 µg β-caroteno/g), enquanto o de linhaça dourada se destacou com maior conteúdo de fenólicos totais (287,29 mg/kg) e o de chia com 199,03 mg/kg de fitosteróis totais. Os óleos avaliados também demonstraram elevada capacidade antioxidante. Assim, é possível concluir que são óleos importantes do ponto de vista funcional, devido à presença de compostos bioativos. </p
... However, unrefined oils like EVOO also contain some other compounds, such as terpenoids, vitamins, carotenoids, and polyphenols, among others which provide a protective effect during cooking (Blasi et al., 2018;Jiménez, García, Bustamante, Barriga, & Robert, 2017). As a consequence of their protective properties these compounds tend to degrade during cooking (Kalantzakis, Blekas, Pegklidou, & Boskou, 2006). In the case of phenolic compounds, previous studies found that despite the degradation, cooking at moderate temperature (i.e., 120 • C), the EVOO preserve enough phenolics to comply with the European Health claim (European Commission Regulation EC No. 432/2012Lozano-Castellón et al., 2020). ...
Article
In this work, the major changes in extra-virgin olive oil (EVOO) composition during cooking were assessed. A foodomics approach based on both metabolomics and lipidomics was used to evaluate the impact of six different cooking techniques, three traditional and three more innovative (Crock-pot®, Roner® and Gastrovac®), and the effect of temperature and cooking time. The lipophilic and hydrophilic fractions of EVOO that underwent different cooking processes were characterized by untargeted high-resolution mass spectrometry approaches. Multivariate statistics were used to unravel the differences in chemical signatures. The different cooking methods resulted in broadly different phytochemical profiles, arising from thermally driven reactions accounting for hydrolysis, synthesis, and oxidation processes. The innovative cooking techniques marginally altered the phytochemical profile of EVOO, whereas sauteing was the cooking method determining the most distinctive profile. Conventional cooking methods (oven, pan-frying, and deep-frying) produced more oxidation products (epoxy- and hydroxy-derivatives of lipids) and markedly induced degradation processes.
... Radical scavenging activity was determined by the method described by Kalantzakis et al. [33], and was defined as the ability of oil to quench the stable 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). Reduction of the amount of free DPPH radical was determined spectrophotometrically by measuring the color change of the reaction solution at 515 nm. ...
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In our study, we assessed whether the addition of basil, fennel, oregano, rosemary, and chili can improve oxidative stability and sensory properties of flaxseed oil (FO) during 180 days of storage or induce oil contamination by microorganisms. Results showed that addition of spices and herbs in FO affected the hydrolytic changes, but far less than 2% of free fatty acids after storage, which was in line with regulations. Further, the addition of spices and herbs in FO decreased peroxide value (even up to 68.7% in FO with oregano) vs. FO whose value increased during storage, indicating increased oxidative stability and prolongation of shelf life of infused oils. The antioxidant activity of the infused oils ranged from 56.40% to 97.66%. In addition, the phenol content was higher in all infused oils (6.81–22.92 mg/kg) vs. FO (5.44 mg/kg), indicating that herbs and spices could scavenge free radicals and inhibit lipid peroxidation, while sensory analysts showed that FO infused with chili had the lowest bitterness intensity. According to the presence of certain microorganisms, results highlighted the need to develop new methods for inactivating microorganisms that would not only provide a microbial safety, but also preserve the beneficial properties of the oils/products.
... IC50 values denote the concentration of the sample, which is required to scavenge 50% of DPPH free radicals. For the analysis of EVOO, the measurement of DPPH was conducted using the analytical methods described by Kalantzakis et al. 18 . EVOO samples were diluted in ethyl acetate (10%, w/v); Nor. ...
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Background: In response to consumer demand for novel and healthy foods, the presence in the market of olive oils (OOs) flavored with different plants, spices, herbs or fruits is increasingly common. All these flavoring agents have been used over the years due to its content in compounds with biological activities. Aim: The aim of this study was to investigate the potential role of the addition of S. montana EO at 100 ppm (0.01%, v/v), known for its high content of bioactive compounds, good flavor, and aroma in improving oxidative stability and quality profile of EVOO subjected to conditions causing accelerated oxidation (Light storage at 900 lux). Materials and methods: The S. montana EO chemical components were identified using Gas Chromatography–Mass Spectrometry (GC/MS). Enriched and non-enriched EVOO samples were examined as function of time (30, 60 and 9 days) of display for different quality indices. Results: Using GC/MS analysis of S. montana EO: thymol (28.36%), carvacrol (17.45%), p-cymene (10.91%), trans-caryophyllene (5.54%), ɤ-terpinene (5.03%) and geraniol (4.50%) were identified. The results highlighted that the enrichment with S. montana EO led to lower values of lipid oxidation indicators (K232, K270, peroxide value) and higher concentration of antioxidants (total phenols and pigments). In sum, the use of bioenrichment methods could be a sustainable solution for the promotion of the quality characteristics of EVOO in Algeria. Keywords: Bioenrichment, Satureja montana L., Essential oil, Extra virgin olive oil, Display, Quality stability.
... IC50 values denote the concentration of the sample, which is required to scavenge 50% of DPPH free radicals. For the analysis of EVOO, the measurement of DPPH was conducted using the analytical methods described by Kalantzakis et al. 18 . EVOO samples were diluted in ethyl acetate (10%, w/v); Nor. ...
Article
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Background: In response to consumer demand for novel and healthy foods, the presence in the market of olive oils (OOs) flavored with different plants, spices, herbs or fruits is increasingly common. All these flavoring agents have been used over the years due to their content in compounds with biological activities. Aim: The aim of this study was to investigate the potential role of the addition of S. montana EO at 100 ppm (0.01%, v/v), known for its high content of bioactive compounds, good flavor, and aroma in improving oxidative stability and quality profile of EVOO subjected to conditions causing accelerated oxidation (Light storage at 900 lux). Materials and methods: The S. montana EO chemical components were identified using Gas Chromatography–Mass Spectrometry (GC/MS). Enriched and non-enriched EVOO samples were examined as function of time (30, 60 and 90 days) of display for different quality indices. Results: Using GC/MS analysis of S. montana EO: thymol (28.36%), carvacrol (17.45%), p-cymene (10.91%), trans-caryophyllene (5.54%), ɤ-terpinene (5.03%) and geraniol (4.50%) were identified. The results highlighted that the enrichment with S. montana EO led to lower values of lipid oxidation indicators (K232, K270, peroxide value) and higher concentration of antioxidants (total phenols and pigments). In sum, the use of bioenrichment methods could be a sustainable solution for the promotion of the quality characteristics of EVOO in Algeria. Keywords: Bioenrichment, Satureja montana L., Essential oil, Extra virgin olive oil, Display, Quality stability.
... The DPPH radical scavenging activity of reconstituted sample was determined following the process of Kalantzakis et al. (2006). To make methanol extracts, 2.5 g tomato powder was dissolved in 10 mL of 70% methanol in a test tube. ...
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The purpose of the study was to optimize the effective drying conditions and different foaming agent concentrations on the biochemical properties of foam mat dried tomato powder. Foaming was achieved by using egg albumin as foaming agent and sodium salt of Carboxymethyl Cellulose (CMC) as foam stabilizer with different concentrations. Drying was achieved by using different drying temperatures. The changes in different physicochemical properties of foam mat dried powder viz. total soluble solid (TSS), pH, ascorbic acid, titratable acidity, β-Carotene, DPPH radical scavenging activity were observed. Foams were prepared from different concentrations of egg albumin (3-7% w/w) and sodium salt of Carboxymethyl Cellulose (1%, 0.5%). The drying temperatures were varied from 60°C to 70°C. The drying time changes with different drying temperatures. It was found that the drying time decreased with the increased foaming agent concentrations as well as with higher drying temperature. It takes almost 13 hrs for drying at 70°C. TSS and pH content was increased with the increase of foaming agent concentrations and foam stabilizer's concentrations but decreased with the increasing temperatures. Ascorbic acid decreased with the increase of foaming agent concentrations and temperatures but increased with CMC concentration. Titratable acidity content of foam mat dried tomato powder was decreased with the increasing foaming agent concentrations but increased with the higher temperatures and decreased CMC concentration. β-Carotene contents increased with the increase of foaming agent concentrations but decreased with the increase of temperatures and foam stabilizer concentration. DPPH free radical scavenging activity increased with the increase of foaming agent, foam stabilizer and temperatures. Based on the maximum retention of physicochemical properties, the optimum treatment of foaming agent was found to be 7% egg white + 1% CMC at 60°C.
... The components were vortexed for 0.5 h and the absorbance of the mixture was then measured at 517 nm using a UV-Vis spectrophotometer. EC 50 value was expressed in mg mL -1 (Brand-Williams et al., 1995;Kalantzakis et al., 2006). ...
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The bioactive compounds and the antioxidant capacities of mangaba, mango and papaya oils were investigated. Determinations of fatty acid composition, tocopherol, phytosterols, phenolic compounds profile, total carotenoids, and antioxidant activity were carried out in the oils of mangaba, mango and papaya seeds. The analysis of antioxidant activity was performed by the methods DPPH•, ABTS•+, FRAP, and β-carotene/linoleic acid. Only essential fatty acid C18:2 was detected, in an average of 6.2%. In contrast, the main fatty acids quantified were oleic, palmitic, and stearic. The amount of phytosterols in mangaba (1951.7 mg kg-1), papaya (3540.3 mg kg-1), and mango (4565.7 mg kg-1) oils was higher than that of conventional oils, such as soybean oil. α-tocopherol was the main tocopherol found in all oils analyzed. Quantities of phenolic compounds were found only in mango seed oil. Papaya seed oil showed high quantity of total carotenoids (49.90 µg g-1). The possible use of the seeds studied to produce oils appears to be favorable. The information available in this study is of great importance for investigations regarding the use of vegetable oils as raw material for food, pharmaceutical, and chemical industries.
... Methanolic/water (80/20:V/V) extraction was performed following the method described by Kalantzakis et al. (2006). A sample of oil (1 g) was dissolved with 5 ml of n-hexane, and then, 5 ml of methanol/water was added. ...
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... Oil sample without extract was considered the control sample. Extraction of polyphenols from enriched oil This procedure was adapted from the methodology described by Kalantzakis et al. (2006). A sample of 2.5 g of oil was added to 5 mL of hexane (99 %) and 5 mL of methanol/water (6/4, v/v), then vortexed for 2 min and centrifuged at 3500 rpm for 10 min. ...
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... To evaluate the antioxidant capability of vegetable oils, it is possible to proceed by a direct determination with a simple dilution of the oil in an nonpolar solvent such as n-hexane (Bordbar et al., 2013) or intermediate polarity with ethyl acetate (Kalantzakis et al., 2006) another way to determine the antioxidant capacity of the oil is by carrying out an extraction of polar compounds with methanol in such a way that the antioxidants present in the vegetable oil will be present in the polar fraction after separation (Owen et al., 2000) and this is what we did in the present study, the methanol fraction obtained served us as a sample for the determination of the antioxidant capacity and also for the determination of the total phenolic compounds (TPC). ...
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... Sopan et al. (2014) reported that the uses of pumpkin powder extracts led to improvement in the absorption of DPPH radical after the reaction between the antioxidant molecules and the extracts, resulting in the scavenging of the radical by hydrogen donation. Kalantzakis et al. (2006) observed a difference in antioxidant activity in many vegetable oils such as soybeans cottonseed, olive oil, sunflower and commercial oils. The cause may be different content of phenolic compounds and tocopherol which directly affect oxidative stress. ...
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... DPPH • scavenging capacity: DPPH • scavenging capacity of sucupira seed oil (100 mg) was determined according to the previously reported procedure using the stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH • ) [24]. This method consists of spectrophotometric measurement of the intensity of color change in the solution, depending on the amount of DPPH • . ...
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The present study aims to evaluate the influence of extraction methods on the quality of bioactive compounds and antioxidant capacity in Pterodon emarginatusVogel (sucupira) oils. The oils were extracted from the sucupira seeds by Soxhlet and by the extraction system of Bligh & Dyer. The oils were analyzed as to fatty acid profile, tocopherols, phytosterols, carotenoids, total phenolics, and total antioxidant capacity. The extraction by Soxhlet showed better yield of total lipids and was more efficient to extract tocopherols, phytosterols, and carotenoids, besides presenting better antioxidant activity by DPPH•. However, this method showed insufficient capacity to extract the polar lipid components of the sample, as evidenced by the low results of total phenolic compounds. On the other hand, the Bligh & Dyer method preserved the fatty acid profile and was also effective to extract higher phenolic compounds content and presented superior antioxidant activity when assessed by FRAP, ABTS•+, and oxidative stability index.
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This study explored the efficacy of rosemary as a natural antioxidant and preservative to combat oxidative rancidity in linseed oil. The characterization of rosemary essential oil and extract demonstrated a high phenolic content, particularly in rosmarinic and carnosic acids. Utilizing optimized mixture design, a potent fat preservative was developed that leveraged the synergistic interactions of these rosemary compounds. The preservative exhibited significant antioxidant activity, evidenced by reductions in acidity levels (0.773 to 1.097) and peroxide values (1.473 to 2.494), as well as notable shifts in extinction values of linseed oil subjected to thermo-oxidative stress. Furthermore, it effectively preserved the stability of key fatty acids, outperforming the synthetic preservative BHT in preventing the oxidation of primary fatty acids, including stearic, oleic, linoleic, and α-linoleic acids. These findings underscored the potential of rosemary-derived preservatives to enhance oxidative stability and extend the shelf life of linseed oil, offering promising implications for food quality and safety.
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Background In some villages in Northern Jordan, farmers boil part of their olive fruit harvest before oil extraction to increase the quantity of oil, get a desirable acquired taste, as they claim, and get additional health benefits. Locals call this oil Boiled oil (BO), and its price is about 20% higher than virgin olive oil (VOO) produced by the same farmer. Objective The hypothesis was that boiling olive fruits may affect the quality of the produced oil. Therefore, our study aimed to determine the chemical and physical characteristics of boiled oil in comparison with VOO and the effect of storage of both types of oils for one year. Methods Total phenolic compounds, ferric-reducing antioxidant power assay (FRAP), and radical scavenging activity (RSA) were evaluated. Moreover, the quality indices of BO and VOO were also evaluated. Results Total phenolic compounds decreased significantly (p <0.05) from 8.7 mg GAE/100g in VOO to 2.47 mg GAE/100g in BO. The antioxidant activity measured using FRAP assay also decreased significantly (p <0.05) from 962 to 379 micromole/kg. Half-maximum inhibitory concentration (IC50) of the RSA was significantly higher (p <0.05) in BO samples (414 mg/ml) in comparison with VOO samples (38.9 mg/ml). Moreover, there was a significant increase (p <0.05) in acid value in BO samples (0.943%) in comparison with VOO samples (0.518%). However, the increase in acid value after one year of storage was higher in VOO than in BO. The peroxide value also increased significantly in boiled oil (500 meq/kg) in comparison with VOO (19 meq/kg). Additionally, a significant increase in ultraviolet absorption was observed in BO at k232 and k270 (3.5), which is considered unsuitable for human consumption compared with VOO (2.43). Conclusion In conclusion, these results showed that boiling olive fruits before oil extraction deteriorates oil quality as expected, and consumers should be educated that this type of oil is hazardous to human health and is a waste of effort and money.
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Vegetable oils like extra virgin olive oil, Moringa oleifera oil, sunflower, and corn oils are regularly used for cooking purposes in the Arabian region. Additionally, the consumption of fried food is becoming increasingly popular in this region. The current study is to find out how temperature affects oils without using food of any kind. The fatty acid and antioxidant profiles of these four vegetable oils (extra virgin olive oil, Moringa oleifera oil, sunflower oil, and corn oil) have been investigated in terms of temperature during deep-frying and re-heating. In this process, an electric fryer is used for deep-frying and reheating oil without adding any kind of food. The collected vegetable oil samples were heated for six hours on five different time periods to a temperature of up to 175 ± 5 °C, and the fatty acid profiles were analysed before and after each cycle by using gas chromatography and were characterized by means of UV and FTIR techniques as well. The composition of oil fatty acids is more affected by re-heating than by deep-frying, as the results indicated. The antioxidant activity of the different oils was assessed using the diphenyl-1-picrylhydrazyl (DPPH) scan; the findings revealed that, whereas antioxidant activity dropped sharply in re-heated oils, it did so gradually for deep-frying samples.
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Olive pests and diseases influence olive oil quality. Ayvalik olive cultivar is important between local cultivars grown in Turkey. This study aimed to monitor the effects of olive pests and diseases (olive fruit fly attack and olive anthracnose) on Ayvalik olive oil quality parameters such as free fatty acids (FFA), peroxide value (PV), specific extinction coefficients (K232, K270, and ΔK). Besides, Ayvalik olive fruits were collected at six harvest times, and the level of ripening with olive pests was also evaluated. Results showed that the FFA level influenced negatively by olive pests, mainly olive anthracnose. At the end of harvesting, FFA of oils from damaged olive anthracnose reached up to 5.42 (% oleic acid). Except for the first harvest period, the other quality parameters remained between limit values, and slight differences were observed between healthy and damaged olives. At the first harvest period, PV and K232 (7.02 mEq O2/kg, 2.22) of olive oil from fly-infected olive had higher values than the other samples. The stage of ripening, healthy, and damaged olives affected slightly certain fatty acids of the oils. Total phenolics, o-diphenol, and α-tocopherol content of oils from healthy fruits had higher values than oils from damaged olives. Besides, the antioxidant activity of oils obtained from healthy olives showed higher values compared to the oils from infected olive fruits.Graphical abstract
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Early studies used extremely overheated fats which were toxic if fed to animals. Later fats and oils were heated in equipments for deep-fat frying under the conditions of good commercial practice. Such heated fats showed no detrimental effects even if fed in long-term feeding trials. The results are reported and critically evaluated. However, certain fractions of the heated fats, e.g. the so called “Total Polar Materials” caused clearly noticeable effects in the feeding studies: growth retardation, increased liver and kidney weights, and disorders of the enzyme system but only if fed in high doses. In the last years several research groups specialized in the use of cell cultures and enzymological methods and gained insight into resorption and metabolism. Model compounds or compound mixtures have been synthesized. Their structure and/or composition deviated more or less from the genuine compounds or fractions of the heated fats and the results of these studies must not be generalized.New analytical procedures allow to isolate well-defined fractions, and quantitative data about their contents in heated fats are obtained: (a) harmless mono- and diglycerides and free fatty acids, (b) dimeric and polymeric triglycerides and dimeric fatty acids, harmless as well because of very low resorption rates and (c) oxidized triglyceride monomers. Their saponification and degradation products are oxidized monomeric and dimeric acids, oxidized cyclic fatty acids, and other polar compounds. These low molecular oxidized compounds are nutritionally suspect.Since 60 years and with considerable effort more or less systematic investigations have been performed in many countries to answer the question, if heated fats are detrimental to health.
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Triolein, trilinolein and a mixture of both (1:1) were heated at 180 °C for 2, 4, 6, 8 and 10 h in the absence of tocopherols or in the presence of α-tocopherol (500 mg kg−1), δ-tocopherol (500 mg kg−1) or a mixture of α-, β-, γ- and δ-tocopherol (200–250 mg kg−1 each). Losses of tocopherols as well as increases in polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10 h heating. Results demonstrated that the antipolymerisation effect of tocopherols at high temperature depended on the degree of unsaturation affecting to a greater extent the less unsaturated substrate, triolein. The maximum effect for the three substrates was found when the tocopherol mixture was added. Interestingly, α-tocopherol losses were very rapid and independent of the unsaturation of the triacylglycerol system under the conditions used, although degradation of the substrate was significantly higher as the degree of unsaturation increased for any period of heating.© 1999 Society of Chemical Industry
Article
The performance of virgin olive oil and a commercial vegetable shortening was investigated during 10 successive pan-fryings of potatoes at 180 °C for a total period of 60 min and during 10 successive deep-fryings at 170 °C for a total period of 120 min. These are typical conditions of Greek domestic cooking. For both the oils tested the effect of pan-frying on K232, K268, K316, α-tocopherol, total polar artefacts, Rancimat induction times, octanoic acid formation and linoleic acid decomposition was worse than the effect of deep-frying on the same variables. The same was true for visible spectrum and total phenols in virgin olive oil. No systematic variations of oleic acid, refractive index and trans-isomers of fatty acids were detected. None of the oils reached the limit of 25–27% total polar artefacts. Both oils performed similarly during pan-frying, while virgin olive oil performed better during deep-frying. A very strong correlation between octanoic acid formation and total polar artefacts in the whole data set was observed.
Article
The objective of this study was to compare the stabilizing effects of tocotrienols and their corresponding tocopherols at 60 °C and 160 °C. Stability was determined in coconut fat by observing the Oil Stability Index (OSI), the peroxide value (POV) and conjugated dienes (CD), α-and β-tocotrienols as well as α-tocopherol induced susceptibility of the systems against oxidative deterioration and reduced the life time of coconut fat. δ-and γ-tocotrienols increased the fat's shelf-life at ambient temperature (60 °C). At frying conditions the antioxidative potential increased in the following order: (α<γ<δ (Tocopherols) α<β<γ<δ (Tocotrienols). Under these conditions γ-and δ-tocotrienols were significantly more active than their corresponding tocopherols. Irrespective of the temperature employed, the protective effects of tocochromanols were dose dependent at 160 °C (mg/kg): 1000>500>100 (tocotrienols) and 5000 > 2000 > 1000 > 100 (tocopherols). Among the tested antioxidants δ-tocopherol and δ-tocotrienol were found to be most efficient against lipid oxidation both at 60 °C and at 160 °C. This study showed, that γ-and δ-tocotrienols, similar to the much better investigated tocopherols, are good food antioxidants to enhance shelf-life of coconut fat both at frying and at low temperature.
Article
The effect of lipid profile, vitamin E and total phenolic content was studied in relation to the antioxidant capacity (measured by ESR) of three edible oils (virgin olive, sunflower and olive oils), using short-time deep fat frying as a model. Physico-chemical changes in the oils were also studied. Samples were analysed before and after 15, 30, 45 and 60 min fryings. Determination of free radicals, by electron spin resonance spectroscopy, revealed the highest antioxidant capacity in virgin olive oil and sunflower oil. This parameter was mainly influenced by vitamin E content, followed by lipid profile and phenolic content. The frying procedure decreased the antioxidant capacity in all tested oils. Sunflower oil underwent more chemical changes by frying than did olive and virgin olive oils. Antioxidant capacity of the edible oils was correlated with polar components and ultraviolet indices but not with peroxide index or acidity value. The use of ESR, as a rapid and very sensitive method for determining antioxidant capacity of edible oils, is suggested.
Article
In a major pathway of the autoxidation of methyl linolenate, peroxyl radicals of the internal hydroperoxides undergo rapid 1,3-cyclisation to form hydroperoxyepidioxides. Because linolenate hydroperoxides are relatively unstable, free radical antioxidants are much less effective in linolenate oils than in linoleate oils. Tocopherols and carotenoids effectively, inhibit photosensitised oxidation of vegetable oils. Direct gas chromatographic analyses of malonaldehyde do not correlate with the TBA test. Model fluorescence studies indicate that malonaldehyde may not be so important in crosslinking with DNA. In contrast to oxidised methyl linoleate, oxidised trilinolein does not form dimers. Although trilinolein oxidises with no preference between the 1(3)- and 2-triglyceride positions, the n-3 double bond of trilinolenin oxidises more in the 1(3)- than in the 2-position. Synthetic triglycerides oxidise in the following decreasing relative rates: LnLnL, LnLLn, LLnL, LLLn (Ln = linolenic and L = linoleic). To estimate the flavour impact of volatile oxidation products their relative threshold values must be considered together with their relative concentration in a given fat.
Article
The frying life of two monoenoic oils, extra virgin olive oil (EVOO) and high oleic acid sunflower oil (HOSO), used to fry potatoes following a domestic frying model, by replenishing the oil in the fryer with fresh oil after each use to maintain the oil volume/fresh potato ratio, was studied by measuring polar content (PC) and triglyceride oligomer (TO) content. A combination of column and high-performance size-exclusion chromatography was used. Changes in the PC and TO content of both oils according to the number of frying uses were adjusted to linear, logarithmic, and power equations. While all three equations reflected the alterations quite accurately (p < 0.001), the logarithmic and power equations defined them best. Frequent replenishment of both frying oils with fresh oil produced a stabilization of PC and TO levels after 20-40 uses. According to the linear adjustment equation, 321 +/- 33 frying operations with EVOO and 290 +/- 40 with HOSO would be needed to raise PC to 25%. To reach the 10% TO level set for discarding oil used in frying, EVOO and HOSO would have to be used 319 +/- 35 and 241 +/- 37 times, respectively. Using the power adjustment, however, the theoretical frying life of both oils would be much higher (at least 4460 frying uses before reaching a 25% PC and 538-1552 uses for the EVOO and 249-1319 uses for the HOSO to reach a 10% TO level). The frying life of EVOO and HOSO would be extended almost indefinitely (at least 170 000 uses) when the logarithmic adjustment was applied. These data suggest that frequent replenishment of used monoenoic oil with fresh oil permits one to fry sets of fresh potatoes a very high number of occasions.
Article
Aim of this study was to evaluate the total antioxidant activity (TAA) of extra virgin olive oil (EVOO) and the effect of heating on the alpha-tocopherol content and TAA in relation to the presence of polyphenols, heating time, and temperature. Experiments included the measurement by ABTS decolorization assay of antioxidant capacity of alpha-tocopherol and 14 simple phenolic compounds present in EVOO, either dissolved in ethanol or added to refined olive oil, and the evaluation of TAA, total phenols, and alpha-tocopherol of six commercial EVOO and three olive oils. Finally, four experimental oils were prepared from refined olive oil containing a fixed amount (300 ppm) of alpha-tocopherol and increasing amounts of polyphenols (25, 125, 225, and 326 ppm) extracted from EVOO. The thermal stability of experimental oils under domestic heating conditions (heating time from 30 to 120 min, heating temperature from 160 to 190 degrees C) was studied by evaluating the loss of alpha-tocopherol and TAA according to a Latin square design. Results indicate that TAA of commercial oils is mainly due to their phenol and alpha-tocopherol content. Heating experiments suggest that polyphenols from EVOO are effective stabilizers of alpha-tocopherol during olive oil heating, thus contributing to the nutritional value of cooked foods.
Article
Virgin olive oils were subjected to simulated common domestic processing, including frying, microwave heating, and boiling with water in a pressure cooker. The impact of these processes on polyphenol content and physicochemical characteristics of oils was assessed. Thermal oxidation of oils at 180 degrees C caused a significant decrease in hydroxytyrosol- and tyrosol-like substances. In contrast, oils heated for 25 h still retained a high proportion of the lignans 1-acetoxypinoresinol and pinoresinol. Thermal oxidation also resulted in a rapid degradation of alpha-tocopherol and the glyceridic fraction of oils. Microwave heating of oils for 10 min caused only minor losses in polyphenols, and the oil degradation was lower than that in thermoxidation assays. Again, lignans were the least affected polyphenols and did not change during microwave heating. Boiling a mixture of virgin olive oil and water in a pressure cooker for 30 min provoked the hydrolysis of the secoiridoid aglycons and the diffusion of the free phenolics hydroxytyrosol and tyrosol from the oil to the water phase. Losses of polyphenols were detected only at pH lower than 6. Moreover, alpha-tocopherol and the glyceridic fraction of oils were not modified during this process. It is worth noting that all the heating methods assayed resulted in more severe polyphenols losses and oil degradation for Arbequina than for Picual oil, which could be related to the lower content in polyunsaturated fatty acids of the latter olive cultivar. These findings may be relevant to the choice of cooking method and olive oil cultivar to increase the intake of olive polyphenols.
Article
The phenol content and antioxidant activity of extra virgin olive oils (EVOOs) differing in their origins and degradation degrees were studied. The o-diphenolic compounds typical of olive oil, namely, the oleuropein derivatives hydroxytyrosol (3',4'-dihydroxyphenylethanol, 3',4'-DHPEA), the dialdehydic form of elenolic acid linked to 3',4'-DHPEA (3',4'-DHPEA-EDA), and an isomer of oleuropein aglycon (3',4'-DHPEA-EA), were analyzed by HPLC. The antioxidant activity was studied by (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radical and hydrogen peroxide; (b) the diaphorase (DIA)/NADH/juglone system, which generates superoxide radical and semiquinonic radical; and (c) the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) test. Results showed that EVOOs with a low degradation level (as evaluated by acidity, peroxide number, and spectroscopic indices K(232), K(270), and deltaK according to the EU Regulation) had a higher content of 3',4'-DHPEA-EDA and a lower content of 3',4'-DHPEA than oils having intermediate and advanced degradation levels. EVOOs with a low degradation degree were 3-5 times more efficient as DPPH scavengers and 2 times more efficient as inhibitors of the XOD-catalyzed reaction than oils with intermediate and advanced degradation levels. The DIA-catalyzed reaction was inhibited by EVOOs having low or intermediate degradation levels but not by the most degraded oils.
Article
The concentration of hydroxytyrosol (3,4-DHPEA) and its secoiridoid derivatives (3,4-DHPEA-EDA and 3,4-DHPEA-EA) in virgin olive oil decreased rapidly when the oil was repeatedly used for preparing french fries in deep-fat frying operations. At the end of the first frying process (10 min at 180 degrees C), the concentration of the dihydroxyphenol components was reduced to 50-60% of the original value, and after six frying operations only about 10% of the initial components remained. However, tyrosol (p-HPEA) and its derivatives (p-HPEA-EDA and p-HPEA-EA) in the oil were much more stable during 12 frying operations. The reduction in their original concentration was much smaller than that for hydroxytyrosol and its derivatives and showed a roughly linear relationship with the number of frying operations. The antioxidant activity of the phenolic extract measured using the DPPH test rapidly diminished during the first six frying processes, from a total antioxidant activity higher than 740 micromol of Trolox/kg down to less than 250 micromol/kg. On the other hand, the concentration of polar compounds, oxidized triacylglycerol monomers (oxTGs), dimeric TGs, and polymerized TGs rapidly increased from the sixth frying operation onward, when the antioxidant activity of the phenolic extract was very low, and as a consequence the oil was much more susceptible to oxidation. The loss of antioxidant activity in the phenolic fraction due to deep-fat frying was confirmed by the storage oil and oil-in-water emulsions containing added extracts from olive oil used for 12 frying operations.
Article
The aim of this study was to compare the contents of the main biochemical compounds and the antioxidant capacity of five Spanish olive oils by four different antioxidant tests and to find out the most valuable oil for disease preventing diets. Fatty acids, sterols and individual antioxidant compounds in Arbequina, Hojiblanca, Extra Virgin, Picual and Lampante Spanish olive oils were determined. Antioxidant activities were done as well using different radical scavenging activities: total radical-trapping antioxidative potential by ABAP (TRAP-ABAP), radical scavenging activity by DPPH (RSA-DPPH), antioxidant assay by beta-carotene-linoleate model system (AA-beta-carotene) and total antioxidant status by ABTS (TAA-ABTS). The highest content of all studied antioxidant compounds (353; 329; 4.6 and 2.7 mg/kg for tocopherols, tocotrienols, polyphenols and o-diphenols, respectively) was found in Extra Virgin oil. Also the highest antioxidant capacity was observed in Extra Virgin oil (668 nM/ml; 29.4%; 40.4% and 2.64 mM TE/kg for TRAP-ABAP, RSA-DPPH, AA- beta-carotene and TAA-ABTS, respectively). The correlation between total phenols and antioxidant capacities measured by four methods was very high, but the highest for the beta-carotene (R = 0.9958). In conclusion, the best method for determination of the antioxidant capacity of olive oils is the beta-carotene test. Extra Virgin olive oil has high organoleptic properties and the highest antioxidant activity. The above-mentioned makes this oil a preferable choice for diseases preventing diets.
Article
Crude vegetable oils are usually oxidatively more stable than the corresponding refined oils. Tocopherols, phospholipids (PL), phytosterols, and phenols are the most important natural antioxidants in crude oils. Processing of vegetable oils, moreover, could induce the formation of antioxidants. Black cumin (Nigella sativa L.), coriander (Coriandrum sativum L.), and niger (Guizotia abyssinica Cass.) crude seed oils were extracted with n-hexane and the oils were further fractionated into neutral lipids (NL), glycolipids (GL), and PL. Crude oils and their fractions were investigated for their radical scavenging activity (RSA) toward the stable galvinoxyl radical by electron spin resonance (ESR) spectrometry and toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical by spectrophotometric method. Coriander seed oil and its fractions exhibited the strongest RSA compared to black cumin and niger seed oils. The data correlated well with the total content of polyunsaturated fatty acids, unsaponifiables, and PL, as well as the initial peroxide values of crude oils. In overall ranking, RSA of oil fractions showed similar patterns wherein the PL exhibited greater activity to scavenge both free radicals followed by GL and NL, respectively. The positive relationship observed between the RSA of crude oils and their color intensity suggests the Maillard reaction products may have contributed to the RSA of seed oils and their polar fractions. The results demonstrate the importance of minor components in crude seed oils on their oxidative stability, which will reflect on their food value and shelf life. As part of the effort to assess the potential of these seed oils, the information is also of importance in processing and utilizing the crude oils and their byproducts.
Article
The antioxidant activity (IC(50)) of extra virgin olive oil (EVOO), commercial olive oil, and other vegetable oils (soybean, sunflower, and corn oil) was determined by UV-vis and by electron paramagnetic resonance (EPR) spectroscopy of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Also, we studied the antioxidant activity of the methanol soluble phase (methanolic, MF) and the nonsoluble phase (lipidic, LF) of oils by the same methods. Similarly, we studied the effect of heating on the antioxidant activity at 160 and 190 degrees C. Also, the MF, containing the polyphenolic substances, was used for measurements of the radical scavenging capacity toward the most important oxygen free radicals, superoxide anion (O(2)(*)(-)) and hydroxyl (HO(*)) radicals. Results showed that soybean oil and EVOO had the highest antioxidant potential and thermal stability. In the case of soybean oil, the antioxidant capacity is the result of its high content of gamma- and delta-tocopherols (with the highest antioxidant capacity and thermostabilities), whereas in EVOO, the antioxidant potential is the result of the combination of specific antioxidant polyphenols, which are acting additionally as effective stabilizers of alpha-tocopherol. The high content of EVOO in tyrosol, hydrotyrosol, and oleuropein and other polyphenolics with radical scavenging abilities toward superoxide anion and hydroxyl radical suggests that olive oil possesses biological properties that could partially account for the observed beneficial health effects of the Mediterranean diet.
Article
Squalene was determined in commercial frying oils and fats (sunflower oil, cottonseed oil, corn oil, soybean oil, palm kernel oil, palm oil, vegetable shortening oil, and cooking fats) sampled during deep-frying of potatoes from 21 restaurants in Athens, Greece, and in domestic frying oils [virgin olive oil (VOO), vegetable shortening and sunflower oil] used during the domestic pan-frying and deep-frying of potatoes. The analyses were carried out after cold saponification of the oils followed by gas chromatography-mass spectrometry of the hexane extract. Quantification was carried out by reference curve, using standard squalene solutions. Fresh vegetable oils and fats were found to contain small amounts of squalene (10.2-49.3 mg/100 g oil or fat), with the exception of fresh VOO, which contained 454 mg/100 g. The squalene content of the frying oils was reduced during frying, its lower concentration found in cooked fats (5.9 mg/100 g fat) and its higher in fried VOO (428 mg/100 g oil) after the first frying session. Squalene appeared to be rather stable during frying. Its retention in used restaurant seed oils and fats remained over 50% even after 30 h of frying while a high recovery of 84-96% was observed during the domestic deep-frying of potatoes in VOO. It seems that by using VOO as frying medium a considerable amount of squalene is absorbed by the fried potatoes, thus becoming part of our diet.
Standard Methods for the Analysis of Oils, Fats and Derivatives. 7 th Edn
  • Iupac
IUPAC: Standard Methods for the Analysis of Oils, Fats and Derivatives. 7 th Edn. Eds. C. Paquot, A. Hautfenne, Blackwell Scientific Publications, Oxford (UK) 1987.
The Oily Press, Dundee (UK)
  • Frankel
Frankel, The Oily Press, Dundee (UK) 1998, pp. 227–248.
Frankel: Frying fats In: Lipid Oxidation
E. N. Frankel: Frying fats. In: Lipid Oxidation. Ed. E. N. Frankel, The Oily Press, Dundee (UK) 1998, pp. 227–248.
  • Wagner
  • Billek