Evaluation of Quality Changes of Leisure Dried Tofu During Storage Based on Electronic Nose

The objective of this study was to detect and distinguish quality changes in the process of storage of leisure dried tofu at room temperature based on an electronic nose (E-nose). Through analysis for multiple modes such as principal component analysis (PCA), linear discriminant analysis (LDA) and discriminant factorial analysis (DFA) of the E-nose, which can be indicated that LDA can clearly distinguish the leisure dried tofu under different storage times; while DFA can classified that dried tofu samples of different storage times with a recognition rate of 83.3%. The main component (protein, fat and carbohydrate) content of the dried tofu is in direct connection with the response values of sensors of the E-nose. The content of protein significantly correlated to S3, fat was significantly correlated with S2 and S6, carbohydrate significantly correlated to S1, and the correlation coefficients were 0.930, 0.984, 0.968, 0.965 (P < 0.01), respectively. The results of comprehensive sense organs, E-nose and main components of the dried tofu suggested that before 60 days the dried tofu presented a high grade and excellent quality, from 90 to 120 days the samples displayed reduced characteristic flavor and the contents of the dried tofu changed to a middle grade. After 150 days the changes in the dried tofu was obviously low in both flavor and contents categories.