Factors controlling the quality and safety of fish using mackerel (Scomber scombrus) shelf-life model in the context of sanitary and phytosanitary (SPS) measures for The Gambian fisheries.

Abstract

Food quality, including safety, is a major concern facing the food industry today. The effects of sanitary and phytosanitary (SPS) measures in the fisheries sector of The Gambia including the factors affecting the safety and spoilage of fish were investigated. Effects of SPS measures are important impediments for exporting fish and fishery products originating from The Gambia to the international food commodity trade. The inadequate scientific and technical expertise in addition to the general lack of information and finance are the major contributing factors to these impediments. The Government must build capacity, improve infrastructure and increase the number of trained personnel to adequately monitor and enforce fish safety and quality for both domestic consumption and exports. It is crucial that the seafood industry upgrade fish processing establishments and comply with the required hygiene and sanitary standards necessary. To minimise post harvest losses and improve fish quality, the use of ice along the production and supply chain must be applied. The effect of icing on colour and texture measurements of mackerel fish showed an increase in lightness of the eyes and gills during the initial 3 days of storage coinciding with a decrease in textural firmness. Deformation of the fish muscle over storage time was highly significant (p< 0.01) for the upper and middle parts but not for the tail end of the fish. A comprehensive evaluation on the effect of storage temperature on sensory, chemical and microbiological assessment of mackerel fish was conducted. Whole un-gutted mackerel fish had a shelf life of 8 days during storage in ice. The average quality index (Ql) was highly correlated (r=0.99) with days of storage. Both total volatile and basic nitrogen (TVB-N) and trimethylamine (TMA) increased during icing storage. The production of TMA and TVB-N as indicated by the correlation (r= 0.97; p< 0.001) was highly significant. A major increase in mean microbial count occurred at day 8; this indicated that the usefulness of total bacterial count as an indicator of spoilage was only clear from day 8. The effects of temperatures proved to be significant on the formation of biogenic amines and on the growth of microorganisms over storage time. Maximum contents of histamine, cadaverine and putrescine were obtained at 25°C. Histamine was not detected at 0**C despite the growth of the Enterobacteriaceae on the samples. Spermidine, spermine and tyramine cannot be used as suitable indicators offish spoilage. The investigation on the effects of environmental conditions on the changes in microbial growth kinetics for Pseudomonas fluorescens, Shewanella putrefaciens and cultures of mixed bacteria from mackerel fish, showed a temperature effect which was highly significant. The maximum growth of the microorganisms was attained at 0 to 5% NaCl concentration and between pH 6.5 and 7. Overall, this study showed that the methods used proved important in evaluating mackerel fish freshness quality. The wider application of the sensory method will be useful for the fishing industry.

Date of Award	2010
Original language	English
Awarding Institution	University of Plymouth