Fermentation of dragon fruit juice by using probiotic lactic acid bacteria

Abstract

Dragon fruit (Hylocereus undatus), a tropical fruit, is rich in valuable nutrients such as vitamins, minerals, and fiber. Therefore, this fruit can be considered as a suitable source for the growth of lactic acid bacteria. In Vietnam, dragon fruit is directly consumed or used for the production of alcoholic fermented beverages. In this study, the juice was fermented by using Lactobacillus acidophilus to fabricate beverages rich in probiotics to diversify the products. The optimal culture conditions are as follows: pH 6.0, initial cell density of lactic acid bacteria 4.8 × 107 (CFU/mL), dry matter concentration 16 °Bx, and fermentation time 72 h. The product consists of 10 log (or 2.5 × 1010 CFU/mL) of L. acidophilus. The survival of probiotics in fermented dragon fruit juice remains at 94.39% after 2 h in the simulated gastric fluid medium and 77.19% after 4 h in the simulated intestinal fluid medium. After 21 days of storage at 4 °C, the viable count of probiotics decreased to 9.91 log.