Bacteriological Profile of Roasted Cashew Nuts within Makurdi Metropolis, Benue State, Nigeria

Abstract

Background: Cashew nuts (Anacardium occidentale L.) are widely consumed for their nutritional and industrial value, but post-harvest handling may expose them to microbial contamination with possible public-health implications. Aims: This study examined the bacteriological profile of roasted cashew nuts sold in Wurukum Market, Makurdi Metropolis, Benue State, Nigeria. Study Design: The study adopted a survey design. Place and Duration of Study: The analysis was carried out at the Microbiology Laboratory, Department of Microbiology, Joseph Surwuan Tarka University, Makurdi, Benue State, between June 2009 and July 2010. Methodology: Thirty roasted cashew nut samples were collected aseptically from five locations within the market. The samples were homogenised, serially diluted and cultured on Nutrient Agar, MacConkey Agar, Mannitol Salt Agar and Salmonella-Shigella Agar. Following incubation at 37 °C for 24-48 h, representative colonies were purified and identified using Gram staining and biochemical tests, including catalase, oxidase, indole, methyl red and citrate utilisation tests. Total viable counts were calculated and interpreted using standard microbiological procedures. Results: The total viable count ranged from 2.6 × 10⁶ to 3.1 × 10⁶ CFU/g, with a mean of 2.8 × 10⁶ CFU/g. Five bacterial genera or species were identified: Staphylococcus aureus, Salmonella spp., Escherichia coli, Shigella spp. and Klebsiella spp. The recovery of E. coli and Shigella spp. suggested possible faecal contamination, whereas Staphylococcus aureus and Klebsiella spp. may have originated from handling or environmental sources. Conclusion: The findings indicate moderate bacterial contamination of roasted cashew nuts sold in the study area. Although the microbial loads were comparable with values reported in related studies, the detection of potential bacterial pathogens in ready-to-eat cashew nuts supports the need for improved hygiene, routine microbial assessment and better post-harvest handling practices.