Study on the quality change and deterioration mechanism of leisure dried tofu under different storage temperature conditions

Abstract

The quality change and deterioration mechanism of leisure dried tofu (LD-tofu) were investigated during storage at 4 °C, 25 °C, and 37 °C for 150 d. The results indicated the protein content, fat content, carbohydrate content, and pH of LD-tofu significantly decreased, while the total viable counts and moisture content increased with a bigger storage time. Moreover, the hardness and springiness of LD-tofu stored at 4 °C and 37 °C for 150 d were 2.43 N and 0.932, as well as 1.44 N and 0.842, respectively. Insights from low-field nuclear magnetic resonance measurements revealed that the bound water in the LD-tofu could be transformed into free water, whereas the free water mobility increased significantly at 25 °C and 37 °C. Additionally, the peroxide value and thiobarbituric acid reactive substances level of LD-tofu stored at 25 °C and 37 °C increased, indicating that the high-temperature storage promoted lipid oxidation. Overall, concrete pieces of evidence were provided for the deterioration in the quality of LD-tofu under high-temperature storage due to changes to the protein gel network structure caused by protein oxidation, induced by lipid oxidation. This work paves the way for the development of reasonable storage programs for LD-tofu.