Abstract

This study was designed to investigate the role of airborne microorganisms in the contamination of post processed garri during sale and distribution under tropical market conditions. Freshly processed garri samples were openly displayed in four different markets in Port Harcourt, Nigeria and the changes in microbial burden of the samples were determined over a period of 30 days. Aerosolised bacterial and fungal counts were determined using the index of microbial air contamination (IMA) procedure by placing sedimentation plates at various locations in stalls where garri was displayed in the markets. The bacteria and fungal IMA levels (55 to 85 CFU/dm²/h) obtained for the different markets were higher than accepted limits (50 CFU/dm²/h) for areas prone to microbial contamination. There was a strong positive correlation (p<0.05) between the extent of the microbial burden of the displayed garri products and the level of (a) bacterial IMA (0.978) and (b) fungal IMA (0.947) in the different markets suggesting that microbial burden of the displayed product was due to contamination by airborne microorganisms. Increase in bacterial and fungal loads of the displayed samples during the period of study was significant (p<0.05) and ranged from 2.78 to 5.62 LogCFUg^-1 and from nil to 4.74 LogCFUg^-1, respectively, while during same period, no significant changes (p>0.05) in microbial load was obtained in the control samples (in packages). Microbial counts obtained exceeded the recommended maximum acceptable limit (3.0 LogCFUg^-1) of mesophilic aerobic bacteria in dried food products. Some the bacterial genera (Bacillus, Salmonella and Escherichia) isolated from the air around stalls were also isolated from the displayed garri samples whereas all the airborne fungal isolates (Aspergillus niger, Geotrichum candidum, Penicillium notatum, Rhodotorula spp., Fusarium spp., Mucor spp. and Cephalosporium spp.) were also present in the displayed garri samples. The results of this study demonstrate the importance of air as the main source of microbial contamination of garri in local markets and the need to encourage hygienic packaging of garri by producers and retailers in order to ensure food safety for millions of consumers.

Key words: Garri, microbial burden, air contamination, market, safety.