Improvement of the yield and flavour quality of sesame oil from aqueous extraction process by moisture conditioning before roasting

This study was to investigate the effect of conditioning and heat-treatments on the yield and quality of sesame oil. Confocal laser scanning microscopy (CLSM) and transmission electron microscopy (TEM) were used to explore the microstructure of sesame cotyledon cells. It was found that cell microstructure and oil body membrane of sesame seeds underwent high-pressure steaming pretreatment (HPS), roasting pretreatment (RP), moisture-conditioning plus roasting pretreatment (MRP) was all damaged. All these thermal treatments, especially MRP, contributing to increased oil yield from 45.85 (untreated) to 91.69%. Furthermore, RP or MRP yielded a higher content of sesamol than untreated sesame, whereas sesamin and seasamolin content, fatty acid composition, acid value and peroxide value showed no significant changes (P > 0.05) between heat-treatments. MRP increased the type and content of volatile compounds, which was beneficial to the strong nut-like aroma. Additionally, MRP had a positive effect on oxidative oil stability (induction time of 10.80 h) with respect to untreated oil (7.82 h).