Process Optimization by Orthogonal Array Design for the Development of a Clarified Beverage Based on Lactic Acid Fermetnation of Jujube Juice

A nutritional beverage was developed based on lactic acid fermentation of jujube juice.Using one-factor-at-a-time and orthogonal array design experiments,we established the optimum conditions for lactic acid fermentation of jujube juice as follows: 6% of an inoculum consisting of Lactobacillus delbrueckii subsp.bulgaricus and Streptococcus thermophilus at a ratio of 2:1,3%(V/V) of raw milk,0.5 g/100 mL of glucose and 38 ℃ for a fermentation duration of 1 d.The maximum acid yield obtained under the optimized conditions was 7.5 g/L.The optimum beverage formulation was 2 g of brown sugar,5 g of white sugar,20 mg of NaCl and 0.5 g of lactic acid per 100 mL of beverage.Antioxidant assays revealed that fermented inferior jujube juice had similar DPPH radical scavenging capacity and total antioxidant capacity to fermented superior jujube juice but better than fermented apple juice and fermented sweet potato juice.