Sterol Oxidation in Ready-to-Eat Infant Foods During Storage

The effect of storage on sterol oxidation of ready-to-eat infant foods was evaluated. Two different liquid infant foods (honey or fruits flavors), prepared with milk and cereals, were stored for 0, 2, 4, 7 and 9 months at 25 °C. Sterol oxidation products (SOP) were isolated by cold saponification, purified by silica solid-phase extraction, and analyzed by gas chromatography (GC) and GC-mass spectrometry. β-Sitosterol was the most representative sterol, followed by cholesterol and campesterol. No significant differences in the total and single SOP content (0.81 mg/kg of product) were observed with respect to storage time and type of sample; the main SOP found was 7-ketositosterol (<0.2 mg/kg of product). The extent of stigmasterol oxidation (2.9%) was higher than that of cholesterol (1.9%) and β-sitosterol (1.4%). The type and quality of raw materials, as well as the processing conditions, seem to greatly influence SOP formation and accumulation in infant foods

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%)

Preliminary study on health-related lipid components of bakery products.

The purpose of this study was to evaluate the presence of health-related lipid components, in particular trans fatty acids and sterol oxidation products, in four bakery products. Both types of components are known for their adverse biological effects, especially the increase of atherogenic risk, and therefore it is advisable to monitor their presence in food products. Trans fatty acids were determined by silver-ion thin-layer chromatography-gas chromatography, whereas sterol oxidation was assessed by gas chromatography and gas chromatography-mass spectrometry determination of 7-keto derivatives (tracers of sterol oxidation). The amount of trans fatty acids (0.02 to 3.13 g/100 g of product), sterols (34.9 to 128.3 mg/100 g of product), and 7-keto derivatives of sterols (1.88 to 3.14 mg/kg of product) varied considerably among samples. The supply of phytosterols (22.5 to 64.0 mg/100 g of product) was not significant, and the extent of oxidation of most phytosterols to its corresponding 7-keto derivative was low (0.29 to 0.84%), except for that of brassicasterol (2.01 to 3.11%). The quality of ingredients and raw materials seems to have greatly influenced the fatty acid profile, stability, safety, and quality of the final product; these ingredients should be chosen with extreme care to decrease their potential negative health effects and to increase safety of these products

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

Dietary plants sterols (phytosterols) have been shown to lower total and LDL cholesterol level in humans. Since phytosterols may protect against coronary heart diseases, they have been recently incorporated into a growing spectrum of functional food. However, phytosterols are prone to oxidation, as cholesterol, and their oxidation products (POP) may have toxic effect on human and animal cells similar to those of cholesterol (COP). The purpose of this study was to evaluate the formation of POP in both oil-in-water (o/w) emulsions and bulk vegetable oil. The samples were stored in the dark at 55oC for 73 days. The extent of lipid oxidation was monitored by measuring the lipid hydroperoxides and hexanal, whereas phytosterols oxidation was determined by gas chromatography. The 7-keto derivatives of phytosterols were chosen as reliable markers of their degree of oxidation. A higher POP level was found in the o/w emulsion with respect to the bulk oil; the latter actually displayed a lower POP content and formation rate. This may be due to the high surface activity of sterols, which would allow them to migrate to the oil-water interface where the oxidative stress is high. This hypothesis was actually confirmed by the interfacial tension measurements performed with the digital tensiometer, which showed that phytosterols had a high degree of surface activity which would allow them to concentrate at the interface of emulsion droplets. Surprisingly, the monounsaturated phytosterols were found to oxidize faster or at a similar rate as the omega-6 polyunsaturated fatty acids in the o/w emulsion and bulk oil, a factor that could also be related to their high surface activity

Effetto dell\u2019arricchimento in &#945;-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 &#945;-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 &#969;-3 ed in acido linoleico coniugato (CLA), \ue8 risultato significativo nei formaggi trattati (pecorini: 2,6% &#969;-3, 2,9% CLA; caprini: 1,9% &#969;-3, 1,3% CLA), rispetto a quelli di controllo (pecorini: 0,9% &#969;-3, 1,1% CLA; caprini: 0,8% &#969;-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 &#969;-3 non ha significativamente favorito l\u2019ossidazione della frazione lipidica dei diversi formaggi, non destando preoccupazione per la salute del consumatore

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

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