Effects of Potassium Alginate and Whey Protein on Quality Characteristics of Alum-Free Sweet Potato Wet Vermicelli Prepared by Traditional Dropping Method

The effects of different addition amounts of potassium alginate and whey protein on the textural properties and cooking characteristics of alum-free sweet potato wet vermicelli prepared by dropping method were investigated in order to solve the problem that sweet potato wet vermicelli was not resistant to cooking and easy to be broken without adding higher amount of alum, and the possible mechanism of potassium alginate and whey protein in improving the quality of wet vermicelli was also examined. The results showed that the tensile strengths of alum-free sweet potato wet vermicelli with 0.4% (w/w, total starch base) potassium alginate and 5% whey protein (w/w, total starch base) were 1.77±0.01 g/mm² and 1.43±0.03 g/mm², respectively. The cooking break times were 72.15±2.61 min and 42.24±2.94 min, respectively. The sensory scores were 93.10±3.38 and 87.41±3.68, respectively, which were comparable to those of wet vermicelli with alum. Further, the addition of potassium alginate and whey protein could improve the gelatinization degree of starch, promote the rapid retrogradation of amylose, facilitate the formation of binder paste with high viscosity and starch dough with high structural stability, and enhance the stacking density of starch granules in wet vermicelli. The above results indicated that 0.4% potassium alginate would be used as green additive to replace alum in the production of alum-free sweet potato wet vermicelli with the traditional dropping method, followed by 5% whey protein.