Optimization of auxiliary drier composition and quality evaluation of lyophilized kiwifruit powder fermented by lactic acid bacteria

Fermentation of lactic acid bacteria can not only improve the sensory quality of fruit and vegetable products, but also improve the nutritional composition and bioavailability rate of fruit and vegetable products. In this study, using 'Ruiyu' kiwifruit as raw material, the optimal fermentation strain was obtained by comparing the growth ability of 4 different lactic acid bacteria to ferment kiwifruit pulp, the optimal drying agent composition of lyophilized kiwifruit powder fermented by lactic acid bacteria was optimized by orthogonal experiment, and the physiochemical indexes, functional indexes, sensory quality, and microstructure were measured. The results showed that Lactiplantibacillus plantarum (LP2) had the optimal fermentation performance and the highest viable bacteria number after fermentation (2.53 lg (CFU/ml)). The optimal drying agent composition was soluble starch addition 12%, maltodextrin 6% and β-cyclodextrin 6%. Under these conditions, viable number of strain LP2 of lyophilized kiwifruit powder after fermentation reached 9.40 lg (CFU/g). The physicochemical indexes of lyophilized kiwifruit powder after strain LP2 fermentation were slightly better than those of unfermented fruit powder. Vitamin C content increased by 42.86%, total phenol content and DPPH free radical clearance increased by 9.19% and 11.37%, respectively. Overall sensory quality of the lyophilized kiwifruit powder was significantly improved (P<0.05) and it had a more loose structure.