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M. C. Dobarganes

M. C. Dobarganes

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189
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Publications (189)
Article
Full-text available
This paper proposes to examine the effect of temperature on the oxidation behavior of biodiesel. Soybean biodiesel was oxidized at different temperatures (room temperature, 60, and 110 °C), and the increase in primary and secondary oxidation products was determined based on the peroxide and anisidine values, respectively, during the induction perio...
Article
Full-text available
The question of whether heated fats in the diet may be detrimental to health is nowadays of the upmost concern, but finding an answer is not easy and requires careful consideration of different aspects of lipid oxidation. This review is divided into two sections. The first part deals with the nature of the new compounds formed at high temperature i...
Article
This paper proposes the use of easy ambient sonic-spray ionization mass spectrometry (EASI-MS) to detect markers of high-level oxidation in biodiesel via a simple and rapid single-shot analytical protocol. Soybean biodiesel was oxidized in Rancimat and then analyzed at different time periods by both EASI-MS and traditional physicochemical methods....
Article
Full-text available
The objective of this study was to know the evolution of the oxidation of soybean oil and biodiesel under the conditions of the oxidation stability test (110 degrees C) using the Rancimat apparatus. Samples were analyzed at different periods of time until the end of the induction period. The analytical determinations related to the changes in oxida...
Article
The analysis of used frying oils to ensure quality of fried foods has become a subject of great concern for health administrations, food processors and consumers, especially since some compounds formed at high temperatures impair the nutritional value of fats and have adverse health effects. At present, three lines of research on the analysis of fr...
Article
Dehydrated o/w emulsions containing sodium caseinate and lactose (sample 1), and gelatine, sucrose and maltodextrin (DE 10) (sample 2) were used to study the influence of homogenisation conditions – homogenisation pressure (15 and 70 MPa) and number of passes (1 and 2) – and the drying method – spray‐drying vs. freeze‐drying – on physicochemical pa...
Article
Native palm trees belong to the Arecaceae family and are among the most useful plant resources in the Amazons. Despite its great diversity and various uses, few species have been study in detail, which makes it necessary to perform more comprehensive studies on the quality and composition of species not yet explored. This study deals with the chara...
Patent
Full-text available
The present invention relates to products obtained from crude olive pomace oil by centrifugation or decantation of the pomace, wherein said products contain a specific composition of triterpenic acids (especially maslinic and oleanolic acids), fatty acids, and ethyl esters; these products are suitable for use as additives in human or animal food pr...
Article
In this paper, the distribution of sterol compounds has been analyzed in 10 samples of new sunflower seeds with high contents of phytosterols. The sunflower seeds were first extracted with hexane and the residual oil was then extracted with a mixture of chloroform:methanol (2:1). In addition, the lipids from the defatted seeds and from the total se...
Article
Full-text available
Olive and sunflower oils were heated at 180 °C for 5, 10 and 15 hours with the aim of defining the changes in the contents of fatty acid methyl esters (FAME) and triacylglycerols (TAG) under frying conditions. Differences between apparent and real loss of FAME or TAG are defined for an adequate interpretation of the changes taking place at high tem...
Article
The use of an ELS detector in NP-HPLC for quantitative analysis of oxidation products in FAME obtained from oils is evaluated in this study. The results obtained have shown that the ELS detector enables the quantitative determination of the hydroperoxides of oleic and linoleic acid methyl esters as a whole, and connected in series with a UV detecto...
Article
Quantitative analysis of the main oxidation products of linoleic acid - hydroperoxy-, keto- and hydroxy-dienes - in refined oils is proposed in this study. The analytical approach consists of derivatization of TAGs into FAMEs and direct analysis by HPLC-UV. Two transmethylation methods run at room temperature were evaluated. The reactants were KOH...
Article
GC-MS and GC-FTIR were complementarily applied to identify oxidation compounds formed under frying conditions in methyl oleate and linoleate heated at 180°C. The study was focused on the compounds that originated through hydroperoxide scission that remain attached to the glyceridic backbone in fats and oils and form part of non-volatile molecules....
Article
Full-text available
The influence of temperature (40, 60 and 80 °C) and addition of α-tocopherol (0, 500 mg/kg) on the formation and distribution of the main oxidation products of linoleic acid, i.e. hydroperoxy-, keto- and hydroxydienes, were studied in samples of fatty acid methyl esters (FAME) derived from high-linoleic (HL) and high-oleic (HO) sunflower oils. In t...
Chapter
: Deep frying, one of the most common processes used for food preparation, is widely used by consumers and the food industry. Owing to the presence of oxygen, high temperature and water the frying process involves numerous reactions among which oxidation and polymerization stand out. This chapter is mainly focused on possibilities for preventing ox...
Article
Full-text available
The action of antioxidants to delay lipid oxidation in fats and oils is well known although most of the information is related to their effects at room temperature during storage or at the moderate temperatures of the accelerated tests to measure oil stability. However, oxidation at the high temperatures of food processes like frying, is more compl...
Article
Full-text available
The objective of this work was to study the quantitative formation of hydroperoxydienes, ketodienes and hydroxydienes during autoxidation at 40 °C of fatty acid methyl esters derived from two sunflower oils with different degree of unsaturation, high-linoleic sunflower oil and high-oleic sunflower oil. The analysis of the oxidation compounds was ca...
Article
Full-text available
The determination of polar compounds is the most commonly applied technique in the analysis of used frying fats and oils. High-temperature gas chromatography allows for a quantitative determination of oxidized monomeric FAME and dimeric FAME thus giving extra information on oil degradation starting from the fraction of polar compounds. Polar compou...
Article
Oxidative rancidity, one of the major causes of quality deterioration in foods, is caused by the oxidative deterioration of lipids by atmospheric oxygen. Lipids oxidize through a complex series of reactions giving rise to a myriad of non-volatile and volatile compounds that are responsible for off-flavours even at concentrations in the parts-per-bi...
Article
The objective of this work was to evaluate the effect of relative humidity (RH) on oxidation of the free and encapsulated oil fractions of dried microencapsulated oils (DMOs) during long-term storage at 30 °C. Sunflower and fish oils with different tocopherol content were encapsulated in a milk-based encapsulation matrix. The total non-volatile oxi...
Article
Full-text available
Discordances exist in epidemiological studies regarding the association between the intake of nutrients and death and disease. We evaluated the social and health profile of persons who consumed olive oil in a prospective population cohort investigation (Pizarra study) with a 6-year follow-up. A food frequency questionnaire and a 7 d quantitative qu...
Patent
Full-text available
Procedure of refining crude olive pomace oil obtained through centrifuging or decantation of the pomace, comprising the stage of filtration of the starting crude olive pomace oil carried out through filters having a pore size comprised in the interval from 0.1 to 20 microns and at a temperature below 70 C, preferentially between 35 and 45 C
Article
This study was aimed at evaluating the effectiveness of phenolic antioxidants with a similar structure but having a different polarity in dried microencapsulated sunflower oil. The antioxidants tested were, on one hand, α-tocopherol and its water soluble analogue, Trolox, and on the other, gallic acid and its ester derivatives, propyl gallate and d...
Article
Full-text available
Peroxide value and the determination of conjugated dienes by UV absorption at 232 nm are normally applied alternatively for the evaluation of primary oxidation compounds. The objective of this study was to define the relationship between both indexes during oil oxidation in sunflower oils with different degree of unsaturation. The oils studied were...
Article
Fats and oils are often submitted to technological treatments before being consumed. Some treatments like refining, hydrogenation, and frying often lead to the formation of modified fatty acids such as cyclic fatty acid monomers (CFAM), geometrical fatty acid isomers, and/or oxidized fatty acids and sterols (cholesterol and phytosterols). Both chol...
Article
The aim of this research was to study lipid oxidation in dried microencapsulated oils (DMOs) under Rancimat test conditions (100 °C, 20 L air/h). Samples were prepared by freeze-drying of sunflower-oil-in-water emulsions containing sodium caseinate and lactose. Lipid oxidation was evaluated in the free and encapsulated oil fractions of DMOs by quan...
Article
Full-text available
The detection of compounds giving information on the use of used frying oils as raw material in the production of biodiesel is of interest to guarantee the quality of the product. In this study, the most characteristic groups of compounds formed after used frying oil transesterification were analyzed by means of the standard technique using gas chr...
Article
Triterpenic acids are natural compounds present in plants and foods with beneficial properties for human health and thus they are desirable in the food, cosmetics and pharmaceutical industries. Pomace olive is considered a good source of these substances. In this study, oleanolic and maslinic acids were found to be the main triterpenic acids identi...
Article
Full-text available
Palm and soybean oils were used in experiments of frying of potatoes in 1 L, household electric deep fryers with a surface-to-volume ratio of 0,3 cm-1. The oils were heated for five hours every day for five consecutive days at a temperature of 183.1 ± 1.7 °C. the evaluation of oil degradation was followed by the increase of polymer contents and cha...
Article
A method based on derivatization to fatty acid methyl esters and GC is proposed for the quantitative analysis of hydroxy acids, keto acids and epoxy acids in fats and oils. Isolation of the analytes by solid-phase extraction is proposed to prevent analytical interferences caused by non-altered fatty acids naturally occurring in oils. In addition, h...
Article
Palm and soybean oils were used in experiments of frying of potatoes in 1 L, household electric deep fryers with a surface-to-volume ratio of 0,3 cm(-1). The oils were heated for five hours every day for five consecutive days at a temperature of 183.1 +/- 1.7 degrees C, the evaluation of oil degradation was followed by the increase of polymer conte...
Article
Full-text available
Na fritura, os óleos e gorduras sofrem degradação formando os compostos polares, como os triacilgliceróis polimerizados e os monômeros de triacilgliceróis oxidados, estes últimos têm sido relacionados a patologias e se constituem de grupos como os monoepoxiácidos, monocetoácidos e monohidroxiácidos. Foram determinados os teores destes três grupos d...
Article
The objective of this work was to study the evolution of oxidation under oxidative stability index (OSI) conditions using the Rancimat apparatus. Sunflower oils with different degrees of unsaturation (conventional high-linoleic sunflower oil, genetically modified high-oleic sunflower oil, and a 1 : 1 mixture of both of them) and virgin olive oil we...
Article
Full-text available
Used frying fats and oils with highly variable and uncontrolled quality are used for the production of biodiesel . The objective of this study was to define the analytical methods useful to obtaining information on the quality of the used frying oils as raw material for biodiesels as well as for the characterization of the biodiesels obtained from...
Article
The objective of the study was to investigate the performance at frying temperature of a new sunflower oil with high content of oleic and palmitic acid (HOHPSO) and containing γ-tocopherol as the most abundant natural antioxidant. HOHPSO either containing α- or γ-tocopherol (HOHPSO-α and HOHPSO-γ, respectively) were obtained from genetically modifi...
Article
The influence of two extraction procedures on the peroxide value (PV) of lipid extracts of powdered infant formulas (IFs) was investigated. Thirteen commercial IFs contained in their original packages were assessed after storage at room temperature for 18months. The extraction procedures mainly differed in the extraction solvent polarity. Extractio...
Article
An analytical procedure, combining adsorption and size-exclusion chromatography, for the accurate quantification of the main groups of compounds present in complex deodoriser distillates, has been developed. Silica columns were used to quantify two fractions differing in polarity. The nonpolar fraction contains hydrocarbons, alkyl esters and trigly...
Article
During frying, it is well-known that a wide variety of chemical reactions results in the formation of new compounds that differ in molecular weight and polarity. This chapter provides a summary of the main groups of alteration compounds formed during frying, resulting from the oil or fat being exposed to high temperatures in the presence of air and...
Article
During frying, fats and oils are heated to high temperatures while exposed to air, resulting in a complex series of reactions that generates a wide array of compounds. From the nutritional point of view, the non-volatile degradation products of used frying fats and oils are most relevant since they remain in the oil, are retained in the food, and a...
Chapter
Edible fats and oils usually contain more than 95% triglycerides. The main characteristics of the acyl groups forming triglycerides are chain length (number of C-atoms) and the number and position of unsaturations in the molecules. Before absorption, triglycerides must be hydrolyzed into free fatty acids and monoglycerides. These triglyceride-deriv...
Article
A new method based on high-performance size-exclusion chromatography (HPSEC) is proposed to quantitate primary and secondary oxidation compounds in model fatty acid methyl esters (FAMEs). The method consists on simply injecting an aliquot sample in HPSEC, without preliminary isolation procedures neither addition of standard internal. Four groups of...
Article
Full-text available
Palm oil, soybean oil and partially hydrogenated soybean oil were used to define the repeatability of oil degradation under thermoxidation in the absence of food and during the frying of potatoes. Total polar compounds and their constituent polymeric triglycerides, oxidized monomeric triglycerides and diglycerides were analyzed. The oils were therm...
Article
Full-text available
The determination of polar compounds by adsorption chromatography is the most accepted method for the analysis of used frying fats due to its high precision and accuracy. However, this method is expensive and time consuming. In this study, a rapid analytical method to determine polar compounds is proposed. Starting from milligrams of sample dissolv...
Article
Full-text available
Most of the present regulations or guidelines on used frying fats and oils for human consumption establish that the content of polar compounds should not be higher than 25% of the oil weight. The standard method for the determination of polar compounds, which is based on adsorption chromatography, is time-consuming and needs laboratory facilities....
Article
The quality of frying oils covering a wide range of oil degradation and degree of unsaturation was analyzed using ultrasonic techniques. Ultrasonic velocity and attenuation decreased with temperature, and the average velocity temperature coefficients were −3.59 and −3.51ms−1°C−1 for monounsaturated (MUO) and polyunsaturated (PUO) oils, respectively...
Article
Full-text available
Samples of cottonseed oil, partially hydrogenated cottonseed oil and their blends, with iodine values between 60 and 110, tocopherol-stripped or not by aluminium oxide treatment, were submitted to thermal oxidation, at 180°C, for 10 hours. Samples were collected at 0, 2, 5, 8 and 10 hours, for the determination of dimers and polymers (degradation c...
Article
Fat absorption, lipid interchange and preferential adsorption of polar compounds on food surfaces were studied during frying of frozen prefried foods. Four frying oils were used to fry frozen potatoes and battered hake. Major and minor changes in food fats and frying oils were determined. Lipid determination after frying demonstrated significant di...
Article
This work was aimed at studying lipid oxidation in dried microencapsulated oils (DMOs) during long-term storage. Samples were prepared by freeze-drying of emulsions containing sodium caseinate and lactose as encapsulating components. Evaluation of lipid oxidation was approached by quantitative analysis of nonvolatile lipid oxidation products and to...
Article
Full-text available
The oxidative quality of commercial fried nuts was evaluated by independent analyses of two lipid fractions, the surface oil, and the internal lipid fraction. The nuts studied were 6 samples of almonds, 10 samples of peanuts, 4 samples of sunflower seeds and 2 samples of cashew nuts. The oil content, peroxide value, polymer content, and fatty acid...
Article
High-oleic, high-palmitic sunflower oil (HOHPSO) is a seed oil from a new mutant sunflower line characterized by increased levels of both oleic acid (>50%) and palmitic acid (>25%) and a high oxidative stability. In this study, its performance at frying temperature was compared with that of palm olein in thermoxidative assays (4 h, 180°C). Also, in...
Article
Major short-chain glycerol-bound compounds were investigated in olive oil (OO) and conventional sunflower oil (SO) during thermoxidation at 180 degrees C for 5, 10, and 15 h. These compounds included methyl heptanoate (C7:0), methyl octanoate (C8:0), methyl 8-oxo-octanoate (8-oxo-C8:0), methyl 9-oxononanoate (9-oxo-C9:0), dimethyl octanodiate (C8:0...
Article
Full-text available
Samples of refined and partially hydrogenated soybean oils, with iodine values between 60 and 130, tocopherol-stripped or not by aluminium oxide treatment, were submitted to thermal oxidation, at 180 °C (during) for 10 hours. Samples were collected at 0, 2, 5, 8 and 10 hours, for the determination of dimers and polymers (degradation compounds) and...
Article
Full-text available
Ozonized Sunflower oil (OLEOZON®) is a therapeutical drug developed at the Ozone Research Center (National Center for Scientific Research). It has been national registered for the treatment of skin infections produced by fungi (1999, 2004) and for the treatment of the giardia lamblia infection (2004). OLEOZON® is a product with a high germicidal po...
Article
In the last decades, silicones and particularly dimethylpolysiloxane (DMPS) added to oils and fats at very low concentrations (1–5 mg/kg) have been widely applied as inhibitors of thermoxidative reactions in deep frying. In this review, information available on the mechanisms of DMPS action during the frying process is summarised. Studies on sample...
Article
Heating fats and oils at high temperature in the presence of air, a common procedure in culinary practices such as frying, results in a complex mixture of oxidation products. These compounds may impair the nutritional value of the food. Among them, there is a growing interest in the group of oxidised triacylglycerol monomers because of their high a...
Article
The formation and evolution of monoepoxy fatty acids, arising from oleic and linoleic acids, were investigated in olive oil and conventional sunflower oil, representatives of monounsaturated and polyunsaturated oils, respectively, during thermoxidation at 180 degrees C for 5, 10, and 15 h. Six monoepoxy fatty acids, cis-9,10- and trans-9,10-epoxyst...
Article
The high temperature antioxidant efficiency of α-tocopherol, α-tocotrienol and a mixture of both on hazelnut oil were evaluated. Crude hazelnut oil (HZO), crude hazelnut oil treated with alumina (THZO), as well as three samples of THZO to which 150 mg kg−1 of α-tocopherol, 140 mg kg−1 of α-tocotrienol or a mixture containing 70 mg kg−1 of α-tocophe...
Article
The aim of this work was to study the evolution of oxidation and the efficiency of phenolic antioxidants in sunflower oil-in-water emulsions containing sodium caseinate and lactose (Cas-Lac) or stabilized by Tween-20 (T-20). Two groups of phenolic antioxidants which are structurally similar were tested, i.e. (1) α-tocopherol and its water-soluble a...
Article
Full-text available
To evaluate the relation between type of dietary fatty acid and degree of insulin resistance. A cross-sectional study. Anthropometrical data were measured in 538 subjects, aged 18-65 Years, selected randomly from the municipal census of Pizarra (Spain). An oral glucose tolerance test (OGTT) was given to all subjects and measurements were made of gl...
Article
The objective of this work was to study the evolution of oxidation in sunflower oils differing in unsaturation degree during long-term storage at room temperature. For this purpose, a combination of adsorption and size-exclusion chromatographies was used for quantification of oxidized triacylglycerol (TG) monomers, dimers, and polymers. Conventiona...