Effect of the solvent type and temperature on phytosterol contents and compositions of wheat straw, bran, and germ extracts.

Wheat fractions, such as bran, germ, and straw, are rich in a number of health beneficial bioactive compounds. However, they have not been exploited to their full capacity for value-added product development. This study examines the potential of recovering phytosterol (PS)-enriched extracts from wheat germ, bran, and straw. The main objective of the study was to evaluate the effect of solvent type and temperature on PS content and composition in straw, bran, and germ extracts. Petroleum ether, chloroform, n-hexane, and ethanol were used as solvents. A pressurized solvent extraction system was used for extraction of wheat fractions. Germ extracts had the highest total PS content followed by straw and bran extracts. Beta-sitosterol, campesterol, and stigmasterol were the main PSs in all of the extracts. Ethanol extraction resulted in the lowest total PS recovery from germ. Solvent type had a significant effect on PS composition in straw extracts. beta-Sitosterol was the most abundant PS in straw hexane extracts (74% of total PS). Petroleum ether, chloroform, and ethanol extracted more stigmasterol than beta-sitosterol from straw. This study demonstrated that the solvent type and temperature had significant effects on both PS content and composition of extracts collected from wheat fractions. Because of the complex nature of the agricultural materials, solvent selection and process optimization need to be based on experimental data. Pressurized solvent extraction is a useful technique to screen complex biological materials for their composition and to determine processing conditions to be optimized.