Physicochemical Indicators Associated with Predicted Microbial Stability of Selected Nigerian Street-Vended Foods: Moisture, Ash, and pH Profiles and Their Public Health Implications

Abstract

Street-vended foods constitute a major component of urban diets in many developing regions; however, their physicochemical quality and spoilage susceptibility remain inadequately characterized. Because direct microbiological enumeration was not performed, physicochemical parameters were used as indirect indicators associated with microbial spoilage susceptibility. This study evaluated the physicochemical properties and inferred microbial stability of selected ready-to-eat Nigerian street foods using moisture content, ash content, and pH as key shelf-life indicators. Food samples were categorized into fried products, bakery items, and fermented/starch-based foods and analyzed using standard oven-drying, dry ashing, and potentiometric pH methods. Data were analyzed using descriptive statistics and one-way ANOVA at p < 0.05. Physicochemical parameters were interpreted within a predictive microbiology framework to infer spoilage susceptibility and microbial persistence potential. Moisture content varied markedly among samples (12.8–74.6%), with fermented foods exhibiting the highest moisture levels, suggesting increased susceptibility to physicochemical deterioration and spoilage under ambient conditions. Fried and bakery products showed intermediate moisture values, reflecting processing-dependent dehydration and formulation effects. Ash content ranged from 1.3–2.9%, indicating variability in mineral composition and possible environmental exposure during processing and vending practices. Distinct pH differences were also observed across food groups, with fermented foods showing acidic pH values (4.0–5.2), whereas fried and bakery foods remained near neutral (5.8–6.6), conditions commonly associated with enhanced microbial survival potential.

Integrated assessment demonstrated that spoilage susceptibility in street-vended foods is influenced by the combined effects of moisture availability and acidity rather than by any single physicochemical parameter. Moisture–pH interaction patterns suggested that foods with elevated moisture content and near-neutral pH may present increased spoilage susceptibility under ambient storage conditions, whereas acidic fermented products displayed comparatively improved predicted stability despite high moisture content.

Overall, the findings highlight the importance of physicochemical indicators as rapid, low-cost tools for preliminary assessment of food quality and inferred spoilage risk in resource-limited settings. The study further emphasizes the relevance of moisture–pH interactions in understanding shelf-life behavior and supporting improved monitoring of street-vended food safety.