Thi Hanh Nguyen¹, Ngoc Cham Nguyen¹, Thi Trang Nguyen¹, Van Hung Nguyen^1,

Soursop (Annona muricata L.) is a typical fruit of South East Asia, North Africa and Pacific regions. This fruit possesses an aromatic flavor and bioactive value, thus developing beverage from soursop is a potential direction, especially into probiotic fermented fruit juice since this type of product has received widespread attention from health-concerning consumers. Among probiotic strains Lactobacillus plantarum is considered to have many properties that are very suitable for fermenting fruit juice products. This work aimed to optimize parameters of fermentation soursop juice using L. plantarum in order to develop fermented soursop juice having the probiotic properties, good sensory quality while maintaining the nutritional and bioactive compounds. For this purpose, varying parameters were examined, including soursop juice (SJ): sugar syrup (SS) concentration of 1:1, 1:1.5 and 1:2; total soluble solids content (TSS) of 14, 16, 18 ^oBx; pH index of 4.5, 5.0, 5.5, 6.0; fermentation temperature of 20, 30, 40°C; and time of 48, 56, 64 hours. The optimum parameters were selected as 10⁷ CFU/mL of L. plantarum LB-1; SJ:SS ratio of 1:2; TSS of 16°Bx; pH 5.0; 48-hour fermentation time at 30°C. The final product achieved total titratable acidity (TTA) of 0.54 ± 0.02 g/100mL, reducing sugar content of 2.13 ± 0.04 g/100mL, TSS of 14.97 ± 0.47 ^oBx, pH of 3.95 ± 0.13, 30.54 ± 0.89 mg/100mL vitamin C and total phenolic content of 172.62 ± 8.16 mg GAE /100mL. The final product met the microbiological safety quality since coliform and mold were undetected, while the yeast count was below the permissible level for beverage. The lactic bacteria content accounted for 6.35×10⁷ CFU/mL. The sensory quality of the final fermented juice was rated moderated like, based on the results of the hedonic rating test where the overall acceptability was 7.69 ± 0.56/9.00.

Low-alcohol fermented beverage, L. plantarum, soursop