Microbial, Chemical and Sensory Properties of Pineapple and Beetroot Juice Blend Fermented Using Mixed Probiotic Lactic Acid Bacteria Cultures (Lactobacillus plantarum and L. Rhamnosus)

The rising demand for functional foods has increased interest in probiotic products beyond traditional dairy sources, particularly among individuals with lactose intolerance, dairy allergies, or those adhering to plant-based diets. Fruit juices such as pineapple and beetroot offer promising non-dairy alternatives for delivering probiotic cultures. This study aimed to analyze the microbial, physicochemical, nutritional, and sensory acceptability profiles of pineapple and beetroot juice blends fermented with a mixed culture of probiotic lactic acid bacteria (Lactobacillus plantarum and Lactobacillus rhamnosus). Juice blends were prepared in varying pineapple-to-beetroot ratios: 90:10 (P90:B10), 80:20 (P80:B20) and 70:30 (P70:B30), alongside 100% pineapple (control-P) and 100% beetroot (Br) juices. All blends were pasteurized and inoculated with the probiotic cultures and fermented for 28 days, except the control-P and 100% Br treatment, which underwent spontaneous fermentation. Lactic acid bacteria (LAB) count analysis showed that all inoculated blends maintained probiotic viability (>7 log CFU/mL) for up to 21 days, with the P90:B10 blend maintaining viability up to 28 days. Yeast or mold growth was not detected in the probiotic blends up to day 21, whereas the control-P and 100%Br treatment exceeded yeast and mold count limits by day 14. Physicochemical analysis for all treatments revealed a significant increase in titratable acidity, accompanied by a decrease in pH and sugar content over the fermentation period in the inoculated blends (P90:B10, P80:B20, P70:B30). Significant differences P < 0.05 in vitamin C content were observed between the control-P and all other treatments on day 1. Among the three blends, P90:B10 achieved the highest overall consumer acceptability. Fermenting pineapple-beetroot juice blends with L. plantarum and L. rhamnosus mixed culture is a feasible approach to producing a safe, palatable, and nutritionally beneficial non-dairy probiotic beverage. The P90:B10 blend was optimal in supporting probiotic viability and achieving desirable consumer sensory attributes and, therefore, would be recommended for future commercialization as a probiotic non-dairy product. Key words: probiotics, lactic acid bacteria, pineapple-beetroot blend, fermentation, functional food