Study of Potential of Lactobacillus casei in Enhancing Antioxidant Compounds and Antioxidant Capacity of Red Dragon Fruit Juice through Fermentation

Chuah, Hui Qian (2020) Study of Potential of Lactobacillus casei in Enhancing Antioxidant Compounds and Antioxidant Capacity of Red Dragon Fruit Juice through Fermentation. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

In recent years, the application of probiotic become more popular in food industry due to its ability to preserve and enhance organoleptic properties of food as well as confers health benefit to human. The major probiotic foods available in the market are dairy based. However, people nowadays tend to switch their interest to non-dairy based probiotic food due to some health and sociocultural concern. In this study, red dragon fruit is used as a medium for lactic acid bacteria, Lactobacillus casei to carry out fermentation. The main focus of this study was to examine the capability of L. casei to enhance antioxidant capacity and compounds of red dragon fruit juice. Red dragon fruit juice was fermented for 1 to 3 days at 37oC in microaerophilic condition and its antioxidant activity was examined using chemical approaches. Furthermore, changes in microbial plate count, pH and soluble solid content were recorded. Statistical analysis was carried out using one way ANOVA with confidence interval 95%. The best fermentation was observed on day 1 as the fermented red dragon fruit juice had the highest total flavonoid content (TFC) (27.581 ± 12.335 QE mg/100ml), DPPH scavenging activity (263.175 ± 32.713 AAE mg/100ml) and ABTS scavenging capacity (721.886 ± 355.954 TE μmol/100ml) although its pH and total soluble solid content were not lowest among day 2 to day 3 fermented juice. However, the total phenolic compound (TPC) and ferric reducing ability power (FRAP) of fermented red dragon fruit showed no significant difference from the fresh fruit sample. TPC and TFC of fermented red dragon fruit juice were not significant correlated to DPPH (r = 0.402; 0.792), FRAP (r = 0.685; 0.758) and ABTS (r = 0.627; 0.711) assays respectively at