Isolation and Characterization of Spoilage Microorganisms from Tomato Paste Products in Supermarkets in Lagos, Lagos State

Tomato paste is a widely consumed food product in Nigerian households, yet its microbiological stability during retail distribution remains inadequately studied. This study isolated and characterized spoilage microorganisms from commercially sold tomato paste products in selected supermarkets in Lagos, South West Nigeria. A total of 45 tomato paste samples from three brands were collected across different expiry stages: within-date, near-expiry, and post-expiry. Standard cultural, morphological, and biochemical methods were applied for bacterial and fungal isolation and identification. Results revealed that near-expiry and post-expiry samples had significantly higher microbial loads than within-date products. Bacteria isolated included Bacillus cereus, Lactobacillus plantarum, Leuconostoc mesenteroides, and Clostridium species. Fungal isolates included Aspergillus niger, Penicillium expansum, and Rhizopus stolonifer. Spoilage was associated with compromised packaging integrity, particularly in canned products with visible denting and in sachet products with micro-perforations. Temperature abuse during storage and post-opening contamination also emerged as significant risk factors. The study highlights the need for more stringent post-production quality control testing, improved consumer labelling on post-opening storage practices, and enhanced cold chain compliance across Lagos retail outlets. Keywords: tomato paste, spoilage microorganisms, Bacillus cereus, food safety, Lagos.