Effect of Low Temperature Storage Period on Some Quality Attributes of Soursop (Annona muricata L.) Juice Fermented using Lactobacillus plantarum and Saccharomyces bayanus

Soursop fruit (Annona muricata L.) is known as a nutritional and biological potential tropical fruit. To our knowledge, no study has been conducted on the changes in quality attributes of multi-strain fermented soursop juice during both ambient and refrigerated temperatures storage. Consequently, this study aimed to investigate the changes of physicochemical properties during 30 days refrigerated storage (4°C) of fermented soursop juice. Following the symbiosis fermentation procedure of Lactobacillus plantarum LB-1 and Saccharomyces bayanus FD-3 for 72 hours, soursop juice then pasteurized at 65°C, 15 minutes. Under low temperature storage conditions, the symbiosis soursop juice retains preeminent quality attributes for 30 days: pH (3.66 ± 0.02), total soluble solids (15.10 ± 0.02°Brix), total sugar (14.493 ± 0.042 g/100mL), reducing sugar (5.501 ± 0.011 g/100mL), total titratable acidity (0.501 ± 0.011%), ethanol content (0.47 ± 0.02%), vitamin C (16.43 ± 0.41 mg/100mL), total phenolic concentration (79.74 ± 0.44 mgGAE/100mL). The 30-day storage product exhibited the microbial quality met the required standards for non-alcoholic beverages of Vietnamese Ministry of Health, with total viable cell counts of 0.63x102 CFU/mL, yeast and mold count of 0.45x102 CFU/mL and no detection of coliform and lactic acid bacteria. The sensory attribute of soursop juice was rated moderated like (7.01 ± 0.37) of overall acceptability at day 30 of storage, showing a slight change compared to day 0 (7.41 ± 0.46). The results of this study have confirmed that the potential shelf life of the combined fermented soursop juice can be extended up to 30 days under refrigerated storage conditions, which is expected to be the basis for fully completing the production process to create commercialization potential, helping to enhance the value of soursop, diversify products and promote economic development in the cultivation area.