Development of an ultrasound assisted method for determination of phytosterols in vegetable oil.

The aims of this study were the optimization and validation of a new ultrasound assisted phytosterol method through analysis of response surface generated from Box-Behnken design. Variables quantity of sample (g), volume of KOH/MeOH (mL) and ultrasound time (s) were investigated in three levels. The evaluation process of the methodology was executed through determination of analytical parameters, such as selectivity, linearity, accuracy, dynamic linear range, "intra-day" accuracy and limits of detection and quantification. Optimized conditions for stigmasterol determination were 0.25g; 2.5mL; 300s; and ß-sitosterol were 0.25g; 5.4mL; 300s. The evaluated conditions and all investigated analytical parameters showed that the method is effective for determination of analytes ß-sitosterol and stigmasterol. This new analytical method has the same efficiency of the traditional method, while significantly reducing the total time of extraction for 300s regarding saponification step when compared to 3600s from the traditional method.

Multi-block data analysis using ComDim for the evaluation of complex samples: Characterization of edible oils.

The ComDim chemometrics method for multi-block analysis was employed to evaluate thirty-two vegetable oil samples analyzed by near infrared (NIR) and ultraviolet-visible (UV-Vis) spectroscopy, and by Gas Chromatography with flame ionization detection (GC-FID) for their fatty acids composition. This unsupervised pattern recognition method was able to extract information from the tables of results that could be presented in informative graphs showing the relationship between the samples through the scores, the predominance of information in particular tables through the saliences and the contribution of the variables in each table which were responsible for the similarities observed in the samples, through the loadings plots. It was possible to infer similarities and differences among the samples studied according to the specific absorption in the UV-Vis and NIR region, as well as their fatty acids composition. The proposed methodology demonstrates the applicability of ComDim for the characterization of samples when different variables (different techniques) describe the same samples. In this particular study, the ComDim chemometrics method was able to discriminate samples by their characteristics and compositions.

Effect of dietary replacement of sunflower oil with perilla oil on the absolute fatty acid composition in Nile tilapia (GIFT).

This study evaluated the effect of the dietary replacement of sunflower oil with perilla oil in Nile tilapia (GIFT strain) at 0, 10, 20 and 30 days. There was an increase in total omega 3 fatty acids (n-3) in muscle tissue (from 63.6 to 181.5 mg g(-1)) and a decrease in total concentration of omega 6 fatty acids (n-6) ranging between 255.6 and 196.1 mgg(-1). Amongst the n-3 fatty acids, the concentrations of alpha-linolenic acid (18:3n-3) and docosahexaenoic acid (20:6n-3) increased by 9.4 and 1.9 times, respectively, after 30 days for the perilla oil-enriched diet. The n-6/n-3, polyunsaturated and saturated fatty acids (PUFA/SFA), and polyunsaturated and monounsaturated fatty acids (PUFA/MUFA) ratios tended to stabilize after 20 days under the perilla oil-enriched diet. Incorporation of perilla oil as a lipid source in the diet of tilapia for 20 or 30 days resulted in significant changes in the fatty acid composition of the fish muscle tissue, contributing to increase its nutritional value.