C: FOOD CHEMISTRY
Effect of Pretreatment with Dehulling and Microwaving on the Flavor Characteristics of Cold-Pressed Rapeseed Oil by GC-MS-PCA and Electronic Nose Discrimination
Article first published online: 18 JUL 2013
© 2013 Institute of Food Technologists®
Journal of Food Science
Volume 78, Issue 7, pages C961–C970, July 2013
How to Cite
Zhou, Q., Yang, M., Huang, F., Zheng, C. and Deng, Q. (2013), Effect of Pretreatment with Dehulling and Microwaving on the Flavor Characteristics of Cold-Pressed Rapeseed Oil by GC-MS-PCA and Electronic Nose Discrimination. Journal of Food Science, 78: C961–C970. doi: 10.1111/1750-3841.12161
- Issue published online: 18 JUL 2013
- Article first published online: 18 JUL 2013
- Manuscript Accepted: 1 APR 2013
- Manuscript Received: 25 JUL 2012
- electronic nose;
Raw and dehulled rapeseeds were treated with microwave energy (800 W) from 1 to 8 min with 1-min intervals at a frequency of 2450 MHz to investigate the influence of microwaving and dehulling pretreatment on the flavor characteristics of rapeseed oil extracted by pressing. Headspace solid phase microextraction was used to isolate the volatile compounds of rapeseed oil, which were then identified by gas chromatography-mass spectrometry analysis. The results indicated that microwave and dehulling pretreatment of rapeseed can significantly influence the kinds and content of volatile compounds. The key flavor compounds in rapeseed oil were oxidized volatiles, heterocyclic compounds, and degradation products of glucosinolates. A pungent compound, 4-isothiocyanato-1-butene, was reduced by 97% in rapeseed treated for 3 min with microwaves energy when compared to the rapeseed oil without any treatment. The pyrazine compounds in the oil appeared after 6 min of microwave pretreatment and give a pleasant roasting flavor when compared to crude oils. Principal component analysis was able to differentiate between oils obtained using 4 pretreatment processes based on volatile compounds and electronic nose. The results showed that dehulling pretreatment could improve the flavor, yet microwaving had a greater effect on the flavor of rapeseed oils.
Traditionally, high yields of rapeseed oil are obtained by directly pressing the seeds, and utilizing a dehulling or microwaving pretreatment before pressing rarely occurs. In this study, we considered flavor difference an important factor in dehulled and microwaved oils. In the future, the use of this technology as a pretreatment process would allow for the production and design of a special flavor of rapeseed oil according to different materials. The reduction of off-flavors derived from seeds and the ability to obtain better overall flavor would be beneficial to rapeseed oil consumption.