EFFECT OF STORAGE TIME ON MICROBIAL LOAD OF SODIUM BENZOATE TREATED COMPOSITE FLOUR AT ROOM TEMPERATURE STORAGE

ABSTRACT This study evaluated the effect of storage duration on microbial proliferation in kunu, a traditional fermented beverage produced from composite flour of finger millet (Tamba), pearl millet and groundnut, preserved with sodium benzoate (0.2% w/v) under room-temperature storage (25±2°C). Five experimental formulations with varying grain ratios (100-75% finger millet, 0-20% pearl millet, 5% groundnut) were analyzed and identified for aerobic mesophilic bacteria and fungi using plate count techniques (PCA/PDA) over 72 hours. Bacterial ranged from 2.0×10² to 3.6×10⁴ CFU/g and 2.0×10² to 5.0×10³ CFU/g for fungal count, with sodium benzoate demonstrating significant antifungal efficacy (p≤0.05) but variable antibacterial effects. Formulations with higher pearl millet content (≥15%) exhibited elevated bacterial counts, correlating with substrate nutrient density, while 100% finger millet samples showed the lowest microbial growth, suggesting synergistic antimicrobial activity between millet phenolics and the preservative. The Isolates identified includes Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Aspergillus niger Candida spp and Penicillium spp, for bacterial and fungal counts respectively, indicating contamination risks from processing hygiene. These findings underscore sodium benzoate’s utility in fungal control but highlight the necessity for integrated preservation approaches combining antimicrobial formulation optimization, stringent hygiene protocols, and supplemental preservation methods to ensure microbial safety in traditional cereal beverages.