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.

Incorporation of conjugated fatty acids into Nile tilapia (Oreochromis niloticus).

BACKGROUND: The aim of this work was to improve the nutritional quality of Nile tilapia meat through enriched diets with conjugated isomers of linolenic acid from tung oil. The transfer process of conjugated fatty acids (CFAs) into fish muscle tissue was evaluated by gas chromatography-flame ionization detection (GC-FID) and easy ambient sonic-spray ionization mass spectrometry (EASI-MS). RESULTS: The results showed that conjugated fatty acids were transferred from enriched diet for muscle tissue of Nile tilapia. Conjugated linoleic acids biosynthesis from conjugated linolenic acids was also observed after 10 days. Other important fatty acids such as docosahexaenoic (DHA), eicosapentaenoic (EPA) and arachidonic (AA) acids were also identified over time; however, DHA showed the highest concentration when compared with EPA and AA compounds. CONCLUSION: Therefore, the nutritional quality of Nile tilapia was improved through feeding with enriched diets. The ingestion of these fish may contribute to reaching adequate levels of daily CFA consumption. Furthermore, other important substances which play an important role in human metabolism, such as EPA, DHA and AA, can also be ingested together with CFA. © 2016 Society of Chemical Industry.