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The simultaneous synthesis of a phytosteryl ester and enrichment of stearidonic acid (SDA) were performed via a one-step lipase-catalyzed esterification of fatty acids from Ahiflower™ seed oil with phytosterol. A commercial lipase (Lipase OF) from Candida rugosa was employed as a biocatalyst. Three solvents were screened and cyclohexane was selected as a suitable reaction medium. The effects of enzyme loading, temperature, and solvent amount were investigated. The conversion as well as the SDA content were significantly improved by adding molecular sieves after 1 h of reaction. The optimum conditions were the enzyme loading of 10% (based on the total substrate weight), the temperature of 30 °C, and the solvent amount of 4 mL (based on a substrate weight of 2 g), respectively. The maximum conversion and SDA content in the residual fatty acid were 81 mol% and 58 mol%, respectively, under the optimum conditions. The SDA content increased a 3.4-fold from 17 mol% in Ahiflower™ seed oil to 58 mol%. [ABSTRACT FROM AUTHOR]

Abstract: The capillary gas chromatographic (GC) separation of complex mixtures of plant steryl and stanyl fatty acid esters was achieved using a medium polar trifluoropropylmethyl polysiloxane as stationary phase. An approach allowing the facile synthesis of steryl/stanyl fatty acid esters was developed, thus creating the basis for a calibration of the method for the different types of ester mixtures to be expected in enriched foods. The usefulness of the approach for the rapid authentication of enriched low-fat products via qualitative and quantitative analysis of intact steryl and stanyl fatty acid esters was demonstrated by analysis of two skimmed milk-drinking yoghurts commercially available on the European market. Combining the extraction of lipids under acidic conditions with the GC separation step showed that one of the products contained a steryl/stanyl ester mixture obtained from long-chain sunflower oil fatty acids and sterols/stanols from tall oil. The other product, however, was shown to contain the rather unusual steryl/stanyl esters of the medium-chain octanoic and decanoic acid as ingredients. [Copyright &y& Elsevier]

Transesterification of phytosterols with short and medium chain fatty acids (MCFAs) ethyl esters and with tributyrin catalyzed by Candida rugosa and Pseudomonas stutzeri TL lipases in solvent-free medium was studied including the effects of temperature, fatty acid specificity, enzyme quantity, the residual activity of each lipase and reduced pressure. More than the 90% of the original phytosterols were transformed into their corresponding phystosteryl esters after 3-4 h reaction at 50-60°C and at 100-350 mbar. The product mixtures containing 40-50% (w/w) phystosteryl esters were then vacuum distilled to remove molar excess of SCFA and MCFA ethyl esters utilized in the enzymatic reaction. By this methodology, purities >95% in short and medium chain phytosteryl esters were finally obtained. Practical applications: The methodology presented here describes a rapid and easy process to prepare phytosteryl esters with short and medium chain fatty acids. The phytosteryl esters produced in this study are expected to have improved their hydrodispersibility and bioavailability in comparison with their corresponding free phytosterols. A lower melting point than the original phytosterol and an improved oil and fat solubility are also expected. Moreover, the SCFA and MCFA could act as a lipid vehicle for fatty acids, improving their half-life in the body and promoting their biological activities. [ABSTRACT FROM AUTHOR]

Abstract: The oxidative stability of different phytosterol compounds during pan-frying was evaluated. Rapeseed oil, rapeseed oil-based liquid margarine and butter oil were used as lipid matrices. Gas chromatographic–mass spectrometric analyses indicated that pan-frying may induce phytosterol oxidation but has no marked effect on phytostanol oxidation; up to 5.1% of original sitosterol and 0.1% of original sitostanol were found as oxides. High-performance size-exclusion chromatographic determinations also revealed a moderate degree of polymerization of lipid matrices. The extents of these deteriorative reactions were determined by frying temperature and time, but also by unsaturation degree and water content of the lipid matrix as well as by structure of the phytosterol compound added. The highest phytosterol oxide content was measured in saturated butter oil enriched with free phytosterols, whereas the highest matrix dimer and polymer contents were found in free phytosterol-enriched liquid margarine, which contained 20% of water. [Copyright &y& Elsevier]

Phytosterol, which is hardly soluble in edible oil, was solubilized at a high concentration by converting it to FA esters by lipase-catalyzed transesterification at temperatures higher than 100°C using powdered Lipase QLM (Meito Sangyo Co., Ltd., Nagoya, Japan). Transesterification was conducted, in sunflower oil containing 10% phytosterol, without adding water or solvent, at 100°C. The conversion rate was 97.1% after 7 h of reaction. The effect of temperature on the conversion rate was also examined. Maximum enzyme activity occurred in the 100–120°C range, and 20% of the maximum activity was retained even at 130°C. When the lipase was recovered by filtration and recycled for repeated reactions at 90°C, the half-life of lipase activity was 260 h. Thus, edible oils with nutritional value could be produced by blending the phytosterol-containing sunflower oil into other edible oils. [ABSTRACT FROM AUTHOR]