PROBIOTICATION OF WATERMELON JUICE (CITRULLUS LANATUS) BY USING LACTIC ACID BACTERIA

Objective: The present study aimed to formulate a novel non-dairy probiotic beverage using watermelon juice as a fermentation substrate and to evaluate its physicochemical and functional attributes. Methods: Watermelon, a widely consumed fruit rich in natural sugars, vitamins, and antioxidants, was selected as an ideal substrate for probiotication. Lactic acid bacteria (LAB) were isolated from milk and characterized through morphological and biochemical analyses. The identified LAB strains were subsequently inoculated into pasteurized watermelon juice and subjected to controlled fermentation. The pH, turbidity, and titratable acidity of the fermenting substrate were monitored on the 1st, 4th, 7th, and 10th d, while viable cell counts (CFU/ml) were assessed on the 4th d. The fermented probiotic juice was further evaluated for antimicrobial efficacy against representative Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Salmonella typhi) pathogens. Results: Watermelon juice, rich in natural sugars and bioactive compounds, was used as a substrate for probiotication using lactic acid bacteria (LAB) isolated from milk. The identified LAB strains were inoculated into pasteurized watermelon juice and fermented under controlled conditions. Fermentation resulted in a progressive decrease in pH with a corresponding increase in titratable acidity, confirming active lactic acid production. Viable LAB counts exceeded the minimum therapeutic level of 3.5×10⁷ CFU/ml, indicating effective probiotic survival. The probioticated juice exhibited significant antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Salmonella typhi. Overall, fermentation enhanced the functional quality of watermelon juice, establishing it as a promising non-dairy probiotic beverage suitable for lactose-intolerant and vegan consumers. Conclusion: The findings demonstrate that watermelon juice fermented with milk-derived lactic acid bacteria constitutes a viable and effective base for developing a health-promoting non-dairy probiotic beverage.