Study on the difference of volatile substances among the japonica brown rice white rice based on GC- MS

GC- MS technology was applied in this article to determinate the volatile constituents of the japonica which was on the same storage period( 90 d),and under different storage conditions in three different forms of existence of japonica,brown rice,and white rice. Principal component analysis( PCA) was used to study the differences of volatile component between different samples,and the results were compared and analyzed,then the results were verified by TIC chromatography.The analysis results showed that the kinds of volatile substances in japonica,brown rice,rice samples were 150,125 and 98 respectively. Volatile substances were the same. There were 7 categories: alkane,benzene olefin,aldehydes,alcohols,ketones,esters,heterocyclic.The larger contribution of them were alkanes,benzene olefin,esters and ketones,and the order of contribution rate of them was alkanes >acid esters > benzene olefins > ketones. Ketones played the biggest role in japonica,alkanes played the biggest role in white rice,while the 7 categories of substance in brown rice were fairly level role. Volatile components in brown rice and white rice were greatly influenced by temperature and moisture,while it in the japonica was relatively stable.From the viewpoint of the stability of the volatile components,in the circulation field,brown rice and rice should not be stored for a long time.