Storage fungi and mycotoxins associated with stored smoked Catfish (&lt;i&gt;Clarias gariepinus&lt;/i&gt;)

Ao Osibona,To Samuel,Oo Ogunyebi

doi:10.4314/jasem.v22i5.6

Abstract

Studies were carried out to determine the occurrence of storage fungi and their respective mycotoxin in stored smoked dried fishes. A total of 45 fishes were bought fresh, smoked and stored under three different storage conditions (an air tight container, a bamboo basket and an iron basket). Using the pour plate method, isolation and identification of storage fungi were carried out weekly for four consecutive weeks from each storage container. Mycotoxin detection and quantification were also carried out on each stored smoked fish samples using Agra-Quant kit. The proximate analysis of the stored fish samples prior to storage, and after storage from each storage container was also analysed. Results revealed five fungal isolates associated with the stored samples namely: Aspergillus flavus, A. fumigatus, A. niger, A. wentii and Penicillium species. Four species of Aspergillus and one Penicillium species were isolated and identified from two of three storage condition used (bamboo basket and iron basket) from third week of storage. It was deduced from the mycotoxins analysis results that Aflatoxin B1 and Ochratoxin were present in the stored smoked samples of the two above mentioned storage containers. Results from the proximate compositions revealed a decrease in the ash content, crude fiber and crude protein as the storage period increases. Fat and moisture content of the stored fish samples were observed to increases weekly throughout the storage period in bamboo basket and an iron basket. In conclusion, it can be deduced that storage container play a vital role in the preservation/shelf -life of smoked dried fish.

Highlights

Smoke drying methods used in Nigeria requires low capital, investment and it is conducted in fishermen camps and fish processing centers in traditional smoking kilns of clay, cement blocks, drums or iron sheets (Eyo, 1992)
In the subsequent weeks of storage, more fluffy patches of different colouration were noted on fish samples in the storage container labelled and C
It can be deduced that of the three storage containers used, storage container A which was air tight is the best storage container for smoked fish products which is in agreement with Gopal and Shankar (2011), that requirements for suitable storage/package of smoked fish include inertness, leak proof, impermeability to oxygen and moisture, low transparency and resistance to abrasion and puncture. It was gathered from the results in this present study that, to prevent mycotoxin contamination in stored smoked fish products, proper storage and package devices should be employed

Summary

Introduction

Fish processing and preservation is carried out mainly to slow down or prevent the enzymatic, microbial and chemical deterioration of fresh fish. A number of processing techniques are in operation in Nigeria These include chilling, freezing, salting, canning, drying and smoking. Fish smoking is the most practiced preservation method in Nigeria. Numerous pathogenic agents isolated from different types of fish are able to grow and produce their toxic secondary metabolites, which are retained in fish flesh even after salting and storage periods. These toxic substances caused serious systemic dysfunctions and public health hazards (Swaminathan and Sparling, 1998). This study aims at investigating storage fungi and mycotoxins associated with stored smoked Catfish (Clarias gariepinus)

Objectives

Methods

Results