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

Soursop (Annona muricata L.) of Annonaceae is a great kind of nutritional and biological potential tropical plant. Fermented fruit products are currently a popular trend in consumption due to their various advantages. Nowadays, in addition to commonly used fermentation methods including alcoholic fermentation, acetic fermentation and lactic fermentation, multi-strain fermentation (or symbiosis) is increasingly applied in food production, especially the fruit juice sector. Through the process of altering the fermented conditions of this research, the appropriate process applied was a combination of 48-hour lactic fermentation with the addition of 10⁷ CFU/mL L. plantarum bacterial strain at 30°C; followed by 24-hour combined alcoholic and lactic fermentation with the addition of 10⁶ CFU/mL S. bayanus yeast strain at 15°C. The suitable conditions for fermentation of soursop fruit juice were established as the dilution ratio of soursop juice (SJ) and water (W) of 1:2; the total soluble solids (TSS) of 16°Brix; pH 5.0. Under these suitable fermentation parameters, the final product achieved total titratable acidity (TTA) of 0.488 ± 0.026%, total sugar content of 14.881 ± 0.189 g/100mL, TSS of 15.37 ± 0.17 ^oBrix, pH index of 3.82 ± 0.04, ethanol content of 0.42 ± 0.01 %v/v, vitamin C concentration of 29.26 ± 0.79 mg/100mL and total phenolic content of 95.35 ± 0.64 mg GAE /100mL. After assessment, the fermented soursop juice met the required microbiological quality standards. The sensory quality of the cocultured fermentation soursop juice was rated moderated like (7.41 ± 0.46 on 9-point hedonic scale).

Soursop, multi-strain fermentation, fruit juice, Lactobacillus plantarum, Saccharomyces bayanus