title: Effect of pretreatment with dehulling and microwaving on the flavor characteristics of cold-pressed rapeseed oil by GC-MS-PCA and electronic nose discrimination.
abstract: 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.
authors.affiliation: Faculty of Department of Product Processing and Nutriology, Oil Crops Research Inst., Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.forename: Mei
authors.initials: M
authors.lastname: Yang
authors.forename: Fenghong
authors.initials: F
authors.lastname: Huang
authors.forename: Chang
authors.initials: C
authors.lastname: Zheng
authors.forename: Qianchun
authors.initials: Q
authors.lastname: Deng
mesh_terms: D029741:Brassica rapa / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D062609:Electronic Nose; D005229:Fatty Acids, Monounsaturated; D005511:Food Handling / Q000379:methods; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D008872:Microwaves; D009812:Odorants / Q000032:analysis*; D010938:Plant Oils / Q000737:chemistry*; D025341:Principal Component Analysis; D000074262:Rapeseed Oil; D012639:Seeds / Q000737:chemistry; D052617:Solid Phase Microextraction; D013649:Taste; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D005229:Fatty Acids, Monounsaturated; D010938:Plant Oils; D000074262:Rapeseed Oil; D055549:Volatile Organic Compounds
keywords: dehulling; electronic nose; flavor; microwave; rapeseed