Storage Stability and Probiotic Viability of Foxtail Millet Probiotic Powder Enriched with High Protein and Fiber

Abstract

Aims: The study aimed to evaluate the storage stability of foxtail millet probiotic powder enriched with high protein and dietary fiber under two storage conditions: room temperature (27 ± 1°C) and refrigeration temperature (7 ± 1°C). Study Design: This was an experimental, laboratory-based study. Place and Duration of Study: The study was conducted at the Department of Dairy Microbiology, Dairy Science College, Hebbal, Bengaluru, Karnataka, India, between January 2024 and October 2024. Methodology: Foxtail millet probiotic powder enriched with high protein and dietary fiber was stored in polypropylene sachets under two storage conditions: room temperature and refrigeration temperature. Samples were systematically drawn at 7-day intervals and analyzed for key quality parameters, including probiotic viability, microbial contaminants, water activity, moisture content, alcoholic acidity, and pH. Statistical analyses were performed using Analysis of Variance (ANOVA), with a 5% significance level. A critical difference (CD) value was employed to determine the statistical significance of observed variations between treatments over the storage period. Results: The storage stability of the optimized foxtail millet probiotic dry mix was assessed at both room temperature (27 ± 1°C) and refrigeration (7 ± 1°C) until spoilage or decline in probiotic viability below the threshold value. Probiotic viability declined significantly under both conditions, with a reduction from 11.04 log₁₀ CFU/g to 8.88 log₁₀ CFU/g at room temperature and 8.81 log₁₀ CFU/g under refrigeration. Water activity and moisture content increased over time, reflecting the hygroscopic nature of the mix, while alcoholic acidity rose significantly in both storage conditions. Despite these changes, the mix maintained probiotic viability above the therapeutic threshold (9 log₁₀ CFU/g) for 84 days at room temperature and 105 days under refrigeration, demonstrating its potential as a stable functional food product. Conclusion: The storage study of foxtail millet probiotic powder demonstrated its stability under both refrigeration and ambient conditions, with probiotic viability exceeding the 1 billion CFU/g threshold for up to 105 days and 84 days, respectively. Significant changes in water activity, moisture content, alcoholic acidity, and pH were observed, highlighting the product’s dynamic response to storage conditions.These results support the feasibility of developing shelf-stable, high-protein, high-fiber probiotic millet powders for the health-conscious market.