Electronic nose analysis on flavor changes of cooked rice made of rice treated with different pressures during cold storage

To explore the feasibility of using electronic nose to detect the flavor of cooked rice and to distinguish between cooked rice with different storage time,and further to study the effect of high pressure treatment on the flavor of cooked rice,electronic nose was used to detect the dynamic changes of volatile compounds in the cooked rice made of rice treated with different pressures during cold storage. Rice that had been soaked at40℃ for 40 min with ratio of rice and water(w/w) as 1∶2 was treated under 200,400 or 600 MPa respectively for 10 min at 15℃ before being steamed for 15 min. The rice without high pressure processing was as controlled trial. The cooked rice was packaged with plastic wrap and then stored at 4℃ for evaluation. During storage,the volatile components in the cooked rice were measured daily by PEN3. Principal component analysis(PCA),loadings analysis(LA),and linear discriminant analysis(LDA) were used to analyze the data obtained by PEN3 in the cooked rice during cold storage and characteristic radar charts were further established. The results showed that pressure affected the production of methane,sulfide,ethanol,aromatic compounds and organic sulfide in the cooked rice during cold storage. The contents of methane,sulfide and ethanol in the 200 MPa rice were the highest,while that of sulfide,aromatic compounds and organic sulfides in the 600 MPa rice were the lowest during storage in the pressure treatments. W5 S and W1 W were more effective for identifying the flavor of the cooked rice. The results of this experiment indicated that electronic nose was sensitive to the changes of volatile compound in cooked rice and could be used to nondestructively test the flavor change of cooked rice. PCA identified the control sample or600 MPa rice with different storage time,and LDA distinguished the 400 or 600 MPa rice with different storage time.