Assessment of storage practices and microbial safety of cowpea (Vigna unguiculata L.) Stored by Farmers and Traders in Sokoto State, Nigeria

Cowpea (Vigna unguiculata) is a vital legume crop in Sokoto State, Nigeria, providing essential nutrients and supporting rural livelihoods. However, poor storage practices compromise its quality and safety, increasing the risk of microbial contamination and postharvest losses. This study assessed the storage methods employed by farmers and traders in Sokoto State and evaluated the microbial safety and moisture content of stored cowpea. A cross-sectional survey of 200 respondents across key cowpea-producing LGAs (Tangaza, Wamakko, Kware, Gada, and Bodinga) was conducted, complemented by laboratory analyses of moisture content and microbial load. Results indicated that polypropylene bags were the most commonly used storage method (52.3%), followed by traditional cribs (18.7%) and plastic containers (12.4%), while hermetic/PICS bags (3.2%) and metal silos (7.6%) were rarely adopted. After six months, hermetic/PICS bags and metal silos maintained the lowest moisture content (10.6–10.9%) and recorded the lowest total bacterial and fungal counts, whereas conventional storage methods exhibited higher moisture (12.8–13.6%) and microbial loads (TBC: 5.2–5.8 log₁₀ CFU/g; TFC: 4.2–4.9 log₁₀ CFU/g). Microbial profiling revealed the presence of pathogenic bacteria (Staphylococcus aureus, Enterobacter spp.) and toxigenic fungi (Aspergillus flavus, Fusarium spp.) in conventional storage, while improved storage systems predominantly harbored non-pathogenic microorganisms. The findings demonstrate that hermetic and airtight storage effectively preserves cowpea quality, limits microbial proliferation, and reduces the risk of contamination, whereas conventional methods increase spoilage and potential health hazards. The study highlights the urgent need for awareness campaigns and increased adoption of improved storage technologies to enhance postharvest management, food safety, and security in Sokoto State.