Levels of phytosterol oxides in enriched and nonenriched spreads: application of a thin-layer chromatography-gas chromatography methodology

The content of phytosterol oxidation products (POPs) in enriched and nonenriched commercial spreads was evaluated by thin-layer chromatography-gas chromatography (TLC-GC). Oxides of beta-sitosterol, campesterol, and stigmasterol were produced by thermo-oxidation (7-hydroxy, 7-keto, and epoxy derivatives) and chemical synthesis (triol derivatives), which were then separated and identified by TLC-GC. Their identification was further confirmed by GC-mass spectrometry (GC-MS). The total amounts of phytosterols found were 6.07 and 0.33 g/100 g of sample in phytosterol-enriched and nonenriched spread, respectively, whereas the total POPs contents were 45.60 and 13.31 mg/kg of sample in the enriched and nonenriched products. The main POPs found were the 7-keto derivatives of all phytosterols analyzed; 7-ketositosterol was the most abundant one (14.96 and 5.93 mg/kg of sample in phytosterol-enriched and nonenriched spread). No beta-epoxy and triol derivatives were detected in both types of samples. The enriched spread presented a lower phytosterol oxidation rate (0.07%) than the nonenriched one (0.41%)

Comparison of the composition of the total fatty acids and the main unsaponifiable components of oils obtained from conventional and genetically modified oleaginous

The analysis of the total fatty acids and the unsaponifiable fraction of oils is usually a helpful tool for tracing their origin and detecting adulterations. The aim of this work was to study and to compare the composition of total fatty acids and the main unsaponifiable components of oils obtained from conventional and genetically modified (GM) oleaginous (high-oleic and high-linoleic rapeseeds, Turkish and Greek cottonseeds and GM and non-GM corn and soybean). Lipids were extracted from the oilseeds and transmethylated. The unsaponifiable fraction was obtained by liquid extraction after cold saponification, and was purified by silica TLC. The quantitative determination and identification of the total fatty acids (FA) and the main unsaponifiable components (linear and triterpenic alcohols, 4-methylsterols and 4-desmethyl-sterols-or sterols-) was performed by CGC and GC-MS. Qualitative and quantitative differences were evinced in the FA profile of the various oilseeds, especially between high-oleic and high-linoleic rapeseeds. No significant differences were detected between the GM and non-GM corn, whereas the GM soybean presented a larger diversity of FA than the non-GM soybean. The Greek cotton oil had twice as much w-3 FA as compared to the Turkish one and both contained cyclic FA. The 4-desmethyl-sterols were the most abundant component of the unsaponifiable fraction in all the oleaginous and there were noticeable quantitative differences between the varieties of oilseeds, especially in the corn. In addition, some components were only found in certain varieties and, thus, could be utilized as tracers: clerosterol in GM soybean, b-sitostanol in the Turkish cotton, D7-stigmastenol and D5-avenasterol in high-linoleic rapeseed. Moreover, citrostadienol was only found in the 4-methyl sterol fraction of high-linoleic rapeseed. These results confirm the importance of the composition of both total fatty acid and unsaponifiable fraction, as means for identification of different varieties of oilseeds and suggest the use of these inexpensive analysis as alternative to PCR for distinguishing between GM and non-GM oleaginous

Effetto dell\u2019arricchimento in α-acido linolenico ed acido linoleico coniugato sulla stabilit\ue0 ossidativa di prodotti lattiero-caseari di diversa specie

L'obiettivo di questa ricerca \ue8 stato quello di valutare l'ossidazione lipidica in diversi tipi di formaggi (pecorini e caprini), arricchiti in α-acido linolenico ed acido linoleico coniugato, al fine di accrescere il loro valore nutraceutico. E\u2019 stato adottato un regime alimentare animale arricchito in semi di lino estruso (capre: 180 g/capo/giorno; pecore: 240 g/capo/giorno) confrontato con una dieta di controllo. L\u2019effetto di tale supplementazione sul contenuto in acidi grassi ω-3 ed in acido linoleico coniugato (CLA), \ue8 risultato significativo nei formaggi trattati (pecorini: 2,6% ω-3, 2,9% CLA; caprini: 1,9% ω-3, 1,3% CLA), rispetto a quelli di controllo (pecorini: 0,9% ω-3, 1,1% CLA; caprini: 0,8% ω-3, 0,8% CLA). Il trattamento ha comportato un aumento significativo del livello di insaturazione dei formaggi (pecorini 46,8%; caprini 42,3%), rispetto a quelli di controllo (pecorini 32,6%; caprini 32,6%). La stagionatura non sembra aver influenzato significativamente la composizione in acidi grassi dei formaggi. Per valutare lo stato ossidativo dei formaggi, sono state eseguite determinazioni dei prodotti primari (numero di perossidi (POV)) e secondari dell\u2019ossidazione lipidica (sostanze reattive all\u2019acido tiobarbiturico (TBARs) e prodotti di ossidazione del colesterolo (COPs)). La determinazione dei suddetti prodotti di ossidazione non ha evidenziato differenze significative, intra- ed interspecie, n\ue9 tra i formaggi arricchiti e quelli di controllo n\ue9 tra gli stessi freschi e stagionati. In generale, \ue8 stato riscontrato un basso contenuto di POV (0,9-2,3 meq O2/Kg lipidi), di TBARs (nd-0,025 mg MDA/Kg formaggio) e di COPs (0,7-1,5 mg/100 g lipidi, corrispondente a 0,2-0,4% di colesterolo ossidato), per cui l\u2019arricchimento in acidi grassi ω-3 non ha significativamente favorito l\u2019ossidazione della frazione lipidica dei diversi formaggi, non destando preoccupazione per la salute del consumatore

Chemical and Physical Stability of Citral and Limonene in SDS-chitosan and Gum Arabic Stabilized Oil-in-Water Emulsions

Citral and limonene are the major flavor components of citrus oils. Both of these compounds can undergo chemical degradation leading to loss of flavor and the formation of undesirable off-flavors. Engineering the interface of emulsion droplets with emulsifiers that inhibit chemical reactions could provide a novel technique to stabilize citral and limonene. At present, emulsified flavor oils are usually stabilized by gum arabic (GA), which is a naturally occurring polysaccharide-protein complex. The objective of this study was to examine if citral and limonene were more stable in emulsions stabilized with a sodium dodecyl sulfate (SDS)-chitosan complex than GA. Citral degraded less in GA-stabilized than in SDS-chitosan-stabilized emulsions at pH 3.0. However, SDS-chitosan-stabilized emulsions were more effective at retarding the formation of the citral oxidation product, p-cymene, than GA-stabilized emulsions. Limonene degradation and the formation of limonene oxidation products, limonene oxide and carvone, were lower in the SDS-chitosan- than GA-stabilized emulsions at pH 3.0. The ability of an SDS-chitosan multilayer emulsifier system to inhibit the oxidative deterioration of citral and limonene could be due to the formation of a cationic and thick emulsion droplet interface that could repel prooxidative metals, thus decreasing prooxidant-lipid interactions

Chemical and Physical Stability of Protein- and Gum Arabic-Stabilized Oil-in-Water Emulsions Containing Limonene

An important flavor component of citrus oils is limonene. Since limonene is lipid soluble, it is often added to foods as an oil-in-water emulsion. However, limonene-containing oil-in-water emulsions are susceptible to both physical instability and oxidative degradation, leading to loss of aroma and formation of off-flavors. Proteins have been found to produce both oxidatively and physically stable emulsions containing triacylglycerols. The objective of this research was to determine if whey protein isolate (WPI) could protect limonene in oil-in-water emulsion droplets more effectively than gum arabic (GA). Limonene degradation and formation of the limonene oxidation products, limonene oxide and carvone, were less in the WPI- than GA-stabilized emulsions at both pHs 3.0 and 7.0. These data suggest that WPI was able to inhibit the oxidative deterioration of limonene in oil-in-water emulsions. The ability of WPI to decrease oxidative reactions could be due to the formation of a cationic emulsion droplet interface at pH 3.0, which can repel prooxidative metals, and/or the ability of amino acids in WPI to scavenge free radical and chelate prooxidative metals

Stability of Citral in Protein- and Gum Arabic-Stabilized Oil-in-Water Emulsions

Citral is a major flavor component of citrus oils that can undergo chemical degradation leading to loss of aroma and formation of off-flavors. Engineering the interface of emulsion droplets with emulsifiers that inhibit chemical reactions could provide a novel technique to stabilize citral. The objective of this study was to determine if citral was more stable in emulsions stabilized with whey protein isolate (WPI) than gum arabic (GA). Degradation of citral was equal to or less in GA- than WPI-stabilized emulsion at pH 3.0 and 7.0. However, formation of the citral oxidation product, p-cymene was greater in the GA- than WPI-stabilized emulsion at pH 3.0 and 7.0. Emulsions stabilized by WPI had a better creaming stability than those stabilized by GA because the protein emulsifier was able to produce smaller lipid droplets during homogenization. These data suggest that WPI was able to inhibit the oxidative deterioration of citral in oil-in-water emulsions. The ability of WPI to decrease oxidative reactions could be due to the formation of a cationic emulsion droplet interface at pH 3.0 which can repel prooxidative metals and/or the ability of amino acids in WPI to scavenge free radical and chelate prooxidative metals

Phytosterol oxidation in oil-in-water emulsions and bulk oil

Dietary plants sterols (phytosterols) have been shown to lower plasma cholesterol level in humans. Since phytosterols may protect against coronary heart diseases, they are being incorporated into functional foods. However, phytosterols are susceptible to oxidative degradation. The purpose of this study was to evaluate the formation of phytosterols oxidation products (POPs) in oil-in-water emulsions and bulk corn oil. The extent of lipid oxidation was monitored by measuring the lipid hydroperoxides and hexanal, whereas 7-keto derivatives of phytosterols were determined by gas chromatography to follow sterol oxidation. A higher POPs level and formation rate was found in the oil-in-water (o/w) emulsion than in the bulk oil. Interfacial tension measurements showed that phytosterols had a high degree of surface activity, which would allow them to migrate to the oil–water interface of the emulsion droplets where oxidative stress is high

Composition of total sterols (4-desmethyl-sterols) in extravirgin olive oils obtained with different extraction technologies and their influence on the oil oxidative stability.

The composition and antioxidant activity of total sterols in extravirgin olive oils obtained with different extraction technologies from olives harvested at two ripening stages, were studied. The antioxidant activity was evaluated with an Oxidative Stability Instrument (OSI), by using a model system (made of a mixture of treated/untreated commercial refined peanut oil) enriched with the total sterol fractions of the extravirgin olive oils. No correlation was found between the OSI time and the extraction technologies, the ripening stages or the actual amount of sterols added. No significant differences were observed in the percent composition of sterols of extravirgin olive oils produced with different technologies during the same harvesting period. The latter, however, had a significant effect on the percentage of beta-sitosterol and 5-avenasterol in extravirgin olive oils produced with the same technology

Total composition of sterols (4-desmethyl-sterols) in extravirgin olive oils obtained with different extraction technologies and their influence on the oil oxidative stability

The oxidative stability of vegetable oils mainly depends on the degree of unsaturation and the content of different compounds, such as biophenols and pigments. Little information is available about the influence of the components of the unsaponifiable fraction on oil stability, except for tocopherols and carotenoids. The aim of this work was to study the composition and antioxidant capacity of total sterols (4-desmethyl-sterols) of extravirgin olive oils obtained with different extraction technologies. The olives were harvested at two different ripening stages in the Aprutino Pescarese area (Pescara-Abruzzo, Italy) and were processed with three extraction systems: by pressure (traditional system) and by centrifugation (continuous system) with and without mill waste water recycling. The unsaponifiable fraction of the oils was obtained by liquid extraction after cold saponification, and the sterol fraction was purified by silica TLC. The qualitative and quantitative determination and identification of the total 4-desmethyl-sterols was performed by CGC and GC-MS, using apolar capillary columns (95% dimethyl-5% diphenyl-polysiloxane). Particular attention was focused on the determination of compound looses and the identification of interferences that can occur at the different steps of the analytical method. The antioxidant capacity of the total sterol fraction was evaluated by measuring its forced oxidative stability with an Oxidative Stability Instrument. A commercial refined vegetable oil, subjected to further elimination of its minor components, was used as model system. The latter was enriched with the 4-desmethyl sterols fractions, extracted from the unsaponifiable matter of the extravirgin olive oils, and was then subjected to forced oxidation

Sterol oxidation in ready-to-eat infant foods

The content of sterol oxidation products (SOP) in ready-to eat infant foods was evaluated by thin-layer chromatography-gas chromatography (TLC-GC). Two different flavor (honey or fruits) liquid infant foods prepared with milk and cereals, were subjected to various storage periods (0, 2, 4, 7 and 9 months) at 25\ubaC. Lipids were extracted, subjected to cold saponification, purified by silica solid-phase, silylated and analyzed by GC. Their identification was further confirmed by TLC and GC-mass spectrometry (GC-MS). The main SOP found were the 7-keto derivatives of all sterols analyzed, being the 7-ketositosterol the most abundant one (0.33 mg/kg of sample). However, alpha- and beta-epoxy derivatives of both sitosterol and cholesterol, as well as cholestanetriol, were detected in the two types of samples. The extent of cholesterol oxidation (0.04%) was twice as much that of phytosterols (0.02%). However, no significant differences in the sterol and SOPs content (average value of 16.4 mg/100g sample and 1.29 mg/kg sample, respectively) of the two infant food formulations, were found. In addition, no significant effects of storage on the SOPs content of both infant food formulations, were detected