Phenotypic Characterization of Toxigenic Fungi, Evaluation and Effect of Post Treatment on Aflatoxin and Ochratoxin A Content in Smoked Fish and Smoked Bush Meat

Abstract

Smoked fish and smoked bush meat constitute a major food for humans and are sometimes consumed without further processing leading to contamination with toxins such as aflatoxin and ochratoxin A in which consumption may have serious impact on public health. This study is aimed at detecting the incidence of aflatoxin and ochratoxin A in smoked fish and smoked bush meat samples in Lokoja, Kogi state. A total of thirty-six (36) samples of smoked fish and smoked bush meat were examined; Eight (8) of which belonged to different species of smoked fish (catfish and tilapia fish) and four (4) different species of smoked bush meat samples purchased in triplicates from Old market, Lokoja. All the fish samples contained ochratoxin A with a content of between 2.3-11 µg/kg while the smoked bush meat samples had ochratoxin A content of 3.8-11.5 µg/kg. Aflatoxin content in the fish samples ranged between 4.8-12.5 µg/kg while in smoked bush meat it had 4.5-13.8 µg/kg. Aspergillus flavus, Penicillium sp., Mucor sp. and Aspergillus niger were the fungi isolated from the samples. Aspergillus niger, Penicillium sp. and Aspergillus flavus produced ochratoxin A while only Aspergillus flavus produced aflatoxin. The smoked fish and smoked bush meat samples were subjected to heat and brine treatments to determine their ability to reduce the concentration of the toxins. After heat treatment of the samples, aflatoxin concentration ranged between 0.019-0.067 µg/kg and for ochratoxin A, the range was between 0.011-0.06 µg/kg. Aflatoxin concentration ranged between 0.017-0.065 µg/kg and ochratoxin A concentration ranged between 0.057 - 0.108 µg/kg after brine treatment and this indicated that both treatments drastically reduced the aflatoxin and ochratoxin A content of the samples though heat treatment was more effective. It is therefore recommended that consumption of smoked fish and smoked bush meat as ready-to-eat without undergoing post treatment be discouraged so as to decrease the likelihood of the occurrence of food intoxication. Also the use of high temperatures of about 80°C or soaking in brine solution (7.5%) should be encouraged for post treatment of these foods before consumption.