# Probiotic Enrichment of Jamun Juice With Streptococcus thermophilus : Effects on Antioxidant Activity and Quality

## TL;DR

This study shows that adding a probiotic to jamun juice improves its health benefits, but refrigeration is needed to maintain quality and probiotic stability.

## Contribution

The study demonstrates the successful enrichment of jamun juice with Streptococcus thermophilus and evaluates its stability and quality under different storage conditions.

## Key findings

- Refrigeration best preserves probiotic stability and sensory quality of the probiotic jamun juice.
- Incubation at 37°C increases microbial growth and antioxidant activity but reduces sensory acceptability.
- Antioxidant activity was highest at 37°C, indicating enhanced probiotic metabolic activity.

## Abstract

The increasing demand for functional beverages has driven interest in incorporating probiotics into fruit juices. This study investigates the functionalization of jamun juice with
Streptococcus thermophilus
(
S. thermophilus
), a thermophilic probiotic bacterium, to enhance its probiotic properties and assess storage stability under varying temperature conditions.
S. thermophilus
was isolated from commercial yogurt and identified through colony morphology, Gram staining, and catalase and oxidase tests. The probiotic culture was cultivated in nutrient broth and inoculated into 250 mL of pasteurized jamun juice using 1 mL of bacterial suspension at a concentration of 1.5 × 108 CFU/mL, resulting in a final concentration of 6.0 × 105 CFU/mL in the juice. The functionalized juice was stored at 37°C (incubation), 25°C (room temperature), and 4°C (refrigeration) for 28 days, during which microbial load, pH, sugar content, antioxidant activity, and sensory acceptability were monitored. Results showed a significant increase in microbial load at 37°C, peaking at 109 CFU/mL by Day 14. At room temperature and refrigeration, microbial growth remained minimal, with levels around 108 to 106 CFU/mL. The pH declined most rapidly at 37°C, and at the same temperature, sugar content decreased to 2.2 mg/mL by Day 21. Antioxidant activity, measured using the DPPH assay, was highest (82.35%) at 37°C, indicating enhanced probiotic metabolic activity. Sensory evaluations revealed improved acceptability with lower temperature storage, particularly at refrigeration temperatures, while higher temperatures led to a decrease in sensory quality. Functionalizing jamun juice with
S. thermophilus
improved its probiotic properties, with temperature playing a key role in maintaining these benefits. Refrigeration preserved both quality and probiotic stability, suggesting the potential of this probiotic jamun juice as a functional beverage. Future research could investigate its long‐term stability, sensory characteristics, and nutritional profile, including the presence of bioactive compounds.

S. thermophilus
isolated from commercial yogurt was successfully incorporated into pasteurized jamun juice, enhancing its probiotic and antioxidant properties. Incubation at 37°C boosted microbial growth and antioxidant activity but reduced sensory quality. Refrigeration best preserved probiotic stability and sensory acceptability, highlighting the juice's potential as a functional beverage.