Comprehensive Evaluation Of Round-Grained Nonglutinousrice Quality Based On Gas Composition With Physical And Physicochemical Property

Comprehensive quality testing and grading of rice during its storage is significant to those rice grain depots, factories in improving detection efficiency as well as the level of automation. In this paper, the electronic nose technology combined with GC-MS applied to study the relationship between odor and grain quality. In order to establish a quality prediction model based on the smell of rice accurately and get a new detection method, the detection of physical, chemical and sensory qualities of stored rice, grading, and extraction for odor characteristic parameters were accoplished.1. Sensory evaluation and physico-chemical inspection methods were used to detect the round-grained nonglutinous Rice of different storage time. The changes of color, hardness together with the content of moisture, protein, fatty acid value, and amylose of round-grained nonglutinous Rice during the storage were investigated.2. Experiments were carried out for optimizing the paramenters of the operation. In different conditions(different headspace generation time, headspace volume and sample quantity), samples in different conditions were detected by electronic nose, and the data were analyzed by PCA and variance analysis, and the optimal paramenters were: temperature25℃, space500mL, sample quantity20g, holding time90min.3. In this paper, odors in the rice during storage were analysised by solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). There were147volatile compounds identified by comparing their mass spectra with those contained in the NIST mass spectral database, including77kinds of hydrocarbons,21kinds of ester,11kinds of alcohols (aldehydes),5kinds of acids,4kinds of ketones (ethers),3kinds of phenols,3kinds of nitrile,3kinds of amine and heterocyclic compounds. In addition, Tetradecane, Pentadecane, Eicosane, Nonanal,1-Octanol,3,7-dimethyl-1-Octanol,2-Pentadecanone,6,10,14-trimethyl,(E)-5,9-Undecadien-2-one,6,10-dimethy1-, Indole,2,3-dihydro-Benzofuran were found correlation wih the the period of storage, and they were main factors of the rice’s spoilage. 4. The electronic nose was used to evaluate odor changes of round-grained nonglutinous Rice with different qualities. Models were established to predict the round-grained nonglutinous Rice based on odor. The result showed the different samples’quality could be well distinguished by S6、S7、S8and S9sensors of the electronic nose. The predicting model of qualities was feasible (accuracy≥95%). This study provides a new method for round-grained nonglutinous Rice qualities evaluation, and it can predict correctly by the model based on odor and provide a theoretical basis for future production.