The Effect of Pretreatment and Packaging Material on the quality of Stored Dried Catfish (Clarias gariepinus)

Abstract

The study was conducted to determine effects of pretreatment and locally available packaging materials on the quality of dried and stored catfish (Clarias gariepinus). The freshly obtained catfish was cut into pieces measuring 20×5×6mm. The treatment group was pre-treated with lemon juice, while the control was prepared without pretreatment. Both the treatment and control were dried using hot air at 80 °C to constant weight. The dried sample was then stored using three packaging materials (aluminum foil, unbleached paper and low-density polyethylene bag) in triplicate and stored in iron basket in the laboratory for observation at 25 °C and 55 % relative humidity. Samples were then taken out from storage for further analysis after every week and finally concluded at six weeks. The analysis done was proximate composition, moisture content, total volatile basic nitrogen (TVBN), bacterial and fungal count. The fresh sample had the following data: 72.49%, 19.72, 5.6, 1.04, 1.15 % for moisture content, protein, fat, crude fibre respectively. That of the pre-treated sample obtained was 72.80% moisture content, 17.01% protein content, 3.37% fat content,0.53% ash content and 1.16% crude fibre content. The moisture content for lemon treated dried cat fish ranged between 28-30% (wb). The result showed that the higher the moisture content, the lower the protein content, ash content and fibre. Therefore, as the moisture content decreased, the protein content, crude fibre, fat and oil content increased. The total volatile basic nitrogen (TVBN) of the fresh sample was higher than that of the lemon treated sample due to its chemical compositions with the mean value of 5.60% for the fresh sample and 2.80% for the lemon treated sample. Bacterial and fungal counts on the fresh samples were more than that of the treated samples. After drying, the only microorganisms that survived the heat were thermophilic microorganisms (Bacillus furinus, Pseudomonas aureginosa and Aspergillus terraus) and they weren’t significantly influenced during storage. The results of the analysis of variance (ANOVA) showed that the most suitable packaging material was aluminum foil and the organic acid added to the fish also helped to prolong shelf life. This is because the aluminum foil preserved the quality of the fish hence the proximate compositions of the fish was better than the fish kept in polyethylene and the paper.