Food safety management practices in the traditional fish processing sector in Ghana and the microbiological safety of selected processed fish products from Ghana
Fish products contribute significantly to protein nutriture, food security, livelihoods and the economy in West Africa. Food safety of processed fish products however remains an important concern. The purpose of this study was to investigate the safety of traditionally processed fish from Ghana. Microbiological analysis of selected traditionally processed fish products was conducted. Challenge tests were employed to determine the effects of storage temperature on survival of Salmonella Typhimurium and Staphylococcus aureus. The effects of salting, temperature, pH and inoculum size on the survival and enterotoxin production of S. aureus was also determined. Food safety surveys were conducted. Self-reported and observed food safety practices and the role of food safety inspectors were assessed. The pH levels observed in all samples were not at optimum levels to inhibit microbial growth. Water activity (aw) levels were: fried bonga (0.82 – 0.95), koobi (0.53 – 0.75), kako (0.55 – 0.70, smoked catfish (0.72 – 0.95), smoked herrings (0.54 – 0.94) and smoked mackerel (0.84 – 0.99). Salmonella and Clostridium perfringens were not detected in 25g and 1g, respectively, of any of the samples. Varying levels of Bacillus cereus, S. aureus and yeast and mould were detected in fried bonga and smoked fish samples. Aerobic bacteria and coliforms were present in 50% and 44.4%, of fried bonga. Only yeast and moulds were detected in kako and koobi at levels of <2 log to 4 log cfu/g in koobi and from <2 log to 5 log cfu/g in kako. High levels of between 5 log10 CFU/g and 6 log10 CFU/g aerobic bacteria were recorded in smoked mackerel. On the basis of aw levels and microbial quality, smoked mackerel and fried bonga were classified as high risk fish products requiring time-temperature control, and salted koobi, kako, smoked herrings and catfish as low risk products. Challenge tests with S. aureus in salted smoked mackerel and catfish showed no growth and no enterotoxin A and B at 4°C. S. aureus numbers increased in smoked catfish and mackerel samples stored at 30oC but decreased with increasing NaCl concentration (p<0.001; r2=0.0507). At 30oC, SEA and SEB were detected in samples formulated with 5% (w/w) NaCl with high inoculum. Samples formulated with higher than 5% (w/w) NaCl suppressed growth and enterotoxin production. Food safety knowledge among respondents was good and consumers were concerned with some aspects of food safety in Ghana although not fish in particular. Very few food handlers had received adequate food safety training, the majority of whom overestimated their food safety compliance, evidenced by observed poor hygiene practices. Only 43.8% of inspectors had higher professional qualifications and 29.2% were trained in HACCP. Inspectors identified lack of information (41.7%), support (41.7%) and operational costs (39.6%) among the barriers to food safety compliance. These findings suggest a need for education at all levels including food safety enforcement professionals. A framework model which integrates all aspects of the findings in developing a national regulatory and policy framework for fish food safety has been proposed. Some of the skills that are missing are identified and suggestions put forward that will benefit traditional fish processing.
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