Influence of microwave pretreatment on the flavor attributes and oxidative stability of cold-pressed rapeseed oil

ABSTRACT

This study investigated the effect of microwave (MW) pretreatment on oil yield and the microstructure of rapeseeds, and examined the variations in oxidative stability, tocopherol content and flavor attributes of rapeseed oils extracted by cold pressing or solvent-based methods. Rapeseed moisture content was adjusted to 15% and the seeds were subjected to MW treatment at 200, 400, and 600 W. Compared to untreated samples with the same moisture content, MW pretreatment significantly (p < 0.05) increased the oil yield (by 9–23%), and total tocopherol contents (by 17–23%). Additionally, the oxidative stability of oils extracted from MW-pretreated rapeseeds was significantly (p < 0.05) improved. The analyses of headspace solid-phase microextraction gas chromatography mass spectrometry showed that the relative amount of of pungent compound 4-isothiocyanato-1-butene reduced by 74–95%, whereas that of the non-pungent compound methallyl cyanide increased by 95% in the oils extracted from MW-pretreated rapeseeds. Heterocyclic compounds such as furans and pyrazines appeared in the oils after MW pretreatment and created a special roasted flavor, suggesting that MW pretreatment had a positive effect on the flavor of rapeseed oils.

KEYWORDS:

• Microwave
• oil
• oxidative stability
• rapeseed
• SPME-GC-MS

Additional information

Funding

This work was financially supported by the Key Research and Development Program of Jiangsu Province (Grants No. BE2016334), Natural Science Foundation of Jiangsu Province, China (Grants Nos. BK20170538 and BK20170534) and China Postdoctoral Science Foundation (Grants Nos. 2016M601742 and 2017M611738). The authors also are grateful to the National Natural Science Foundation of China (Grants No. 31501427), Foundation of Key Laboratory of Agricultural Products Physical Processing in Jiangsu Province (JAPP2014-3), the Senior Professional Research Start-up Fund of Jiangsu University (14JDG180), Young Backbone Teachers Program of Jiangsu University, the Nature Science Foundation of the Jiangsu Provincial Education Department (11KJB550001), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).