Abstract:Whey fermented powder possesses important application potential as a natural and green food preservative. In this study，whey was used as the substrate to screen lactic acid bacterial strains suitable for whey fermentation，optimize the fermentation process parameters，and characterize the storage stability of whey fermented powder. The results indicated that the fermented whey produced by single-strain fermentation with Pediococcus acidilactici NF5 presented the highest acidity with a pH value of 4.009±0.010 and the optimal sensory quality. The microbial inoculant prepared by freeze-drying achieved a viable count of 8.466×109 CFU/mL with a high survival rate of 92.33% and excellent storage stability. Taking pH value，titratable acidity and sensory scores as evaluation indices，single-factor and orthogonal experiments were conducted to determine the optimal fermentation conditions：inoculation size of 4%，fermentation temperature of 43.0 ℃，and fermentation duration of 60 h. Under the optimized conditions，the obtained whey fermented powder had a pH of 4.009±0.010，lactose content of 5.34%，protein content of 3.38%，and protein hydrolysis degree of 13.13%，showing favorable storage stability.