Storage Quality Variation, Evaluation Model, and Correlation with Volatile Compounds of Embryo Rice

In order to evaluate the quality changes of embryo rice during storage, the embryo rice with vacuum packaging of two kinds of materials was stored at 25 and 4 ℃ for 300 d and the changes in the fatty acid value, taste, texture, and other indexes were analyzed. A quality evaluation model was constructed based on principal component analysis and entropy weight method. The volatile compounds were determined using Headspace-Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS) to further explore the correlation between the indexes. The results showed that with prolonged storage time, fatty acid value, hardness, and chewiness increased significantly (P<0.05), springiness and taste value decreased significantly (P<0.05), and lipase and malondialdehyde (MDA) first increased and then decreased. A quality evaluation model of embryo rice was established based on seven core indexes: Y=0.0803×chewability+0.1170×springiness+0.1221×flavor+0.1182×taste value comprehensive score+0.2215×malondialdehyde+0.2234×lipase activity+0.1175×fatty acid value. According to the comprehensive scores obtained by the model, the quality of the embryo rice at different storage periods was classified as grade I after 0 d of storage, grade II after 60 d of storage, grade III after 120 d of storage, and grade IV after 180 d of storage. A total of 53 volatile compounds were detected, among which aldehydes, ketones, acids, and other compounds appeared in large quantities after 300 d of storage. There was a significant negative correlation between 2,2,6-trimethyloctane and fatty acid value, lipase, malondialdehyde, hardness, chewability, b^*, or ∆E (P<0.05) and a significant positive correlation between the taste value and quality evaluation comprehensive score (P<0.05), followed by 2-n-propyl furan and 3-methylundecane. These results provide a theoretical basis for quality evaluation and storage method selection of embryo rice.