The alleviative effect of sweet potato protein hydrolysates on the quality deterioration of frozen dough bread in comparison to trehalose

The effects of different sweet potato protein hydrolysates (SPPH) concentrations (1, 2, 3, g/100 g) on the frozen dough bread in comparison to trehalose (3 g/100 g) were evaluated. The results showed that the addition of SPPH at all examined levels can retard the quality deterioration of frozen dough and a greater amount of SPPH showed better effect. During the frozen storage, the addition of 3 g SPPH showed an increase in yeast viability from 43.01% to 79.03%, and a decrease in freezable water content, tan δ and free sulfhydryl groups from 57. 21%, 0.74 and 5.74 μmol/g to 47.72%, 0.69 and 3.96 μmol/g, respectively. After frozen storage for 56 days, compared with the control, the addition of SPPH at 3 g significantly increased the specific volume of bread from 3.15 mL/g to 3.97 mL/g, and the porosity and mean area of pore increased from 23.18%, 0.26–32.55%, 0.43, respectively, authenticated by the observations of SEM, binary and representative images. Furthermore, the hardness significantly decreased from 1224.90 g to 839.93 g. These findings suggested that SPPH can be potently employed as a natural food-derived cryoprotectant agent for improving the quality and nutrition of frozen dough.