Effect of Storage Positions on the Volatile Flavor Compounds (VFCs) of Paddy Rice through Gas Chromatography-Ion Mobility Spectroscopy (GC-IMS) Analysis

The storage positions in the granary has a great influence on the quality of stored grain. In the present study, the changes of volatile flavor compounds (VFCs) in paddy rice stored at middle cold core layer and top layer of the granary during 18 months of storage were analyzed by gas chromatography-ion mobility spectroscopy (GC-IMS), and the effect of storage location on the VFCs of paddy rice in high and big one-store granary were discussed. The results showed that the VFCs in paddy rice changed continuously with the storage time and the longer the time, the greater the change, especially for paddy rice stored at top layer. Compared with that stored at middle cold core layer, the contents of aldehydes and esters in paddy rice stored at top layer for 12 and 18 months were much higher, while that of the alcohols was relatively low, and the largest difference between middle cold core layer and top layer was found in paddy rice stored for 12 months by the principal component analysis (PCA). Among them, the contents of aldehydes and esters including valeraldehyde, nonanal, ethyl acetate, propyl acetate, butyl acetate and isooctanol at the top layer were significantly higher than that at the middle cold layer; while the contents of alcohol and ketone including trans 2-hexene alcohol, 2-pentylfuran, 1-octene-3-ol, heptanol, 1-propanol, 1-hexanol, 1-pentanol, isobutanol and 2-heptanone was higher in paddy rice stored at middle cold core layer. These results indicated that the storage location in the granary has great impact on the flavor characteristics of paddy rice, especially for that stored at top layer which was more affected by the ambient temperature.