Effect of gamma irradiation on the quality of processed anchovies (Engraulis encrasicolus)

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September, 2015
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The effect of irradiation on nutritional composition, microbial load and shelf-life of anchovies (Engraulis encrasicolus) was assessed in this study. Irradiation doses used for the study were 2.5, 5.0, 7.5 and 10 kGy. The assessment was carried out at 3 weeks intervals for the period of 9 weeks. Samples were analysed for microbial load (total viable count, total coliform count and Staphylococcus aureus) and nutritional composition (total ash content and free fatty acids). Smoked anchovies were contaminated with TVC of 6.175 CFU/g when compared to smoked samples (6.042 CFU/g) from Keta at week 0. The sun-dried samples obtained from Chorkor at week 0, had significantly higher (p<0.05) TVC of 5.633 CFU/g when compared to sun-dried samples (4.490 CFU/g) from Keta. It was established on the 9th week that, there was a general decrease in microbes implying that the application of irradiation had reduced the level of TVC, TCC and SA in the anchovy samples. Samples from Chorkor were also found out to be more contaminated than those Keta and this may be as a result of the environmental condition in Chorkor. It was also established that irradiation dose as low as 2.5kGy could decontaminate processed anchovies. As regards, nutritional analysis, sun-dried samples obtained from processors (21.47%) had high amount of ash content when compared to marketers (20.80%) on the 3rd week. Smoked samples obtained from marketers (17.99%) at week 3 were not significantly different (p>0.05) in ash content when compared to processors (18.44%). The free fatty acids (oleic acid) levels in both smoked and sun-dried samples decreased as the storage period increased. Application of irradiation had no influence on the ash content in samples but the free fatty acid levels reduced as the irradiation dose increased. In conclusion, irradiation to a dose of 2.5kGy is sufficient to decontaminate anchovies without significantly affecting their nutritional composition.
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A thesis submitted to The School Of Research And Graduate Studies, Kwame Nkrumah University Of Science And Technology, Kumasi, in partial fulfillment of the requirements for the degree of Master of Philosophy in Postharvest Technology,
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