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Abstract - In this study, we have investigated the potential changes in the number of total and psychotrophic microorganisms, coliform, E. coli, S. aureus, Salmonella spp. and Listeria spp. in the fillet of skinned and skinnless tench fish, which were treated in three different ways and cold-stored for six months. It was concluded that freezing and storing procedures could not destroy the microorganisms totally, and as the best way to inhibit the improvement of microorganisms, one should apply glaze method after treating fish skinnless.
Key word: Blast-freezing, fillet, frozen storage, glazing, tench.
INTRODUCTION Among many currently used methods for food preservation, those based on the action of low temperatures--refrigeration and freezing--are some of the most important ones (Campanone et al., 2006). At 0oC, growth of microorganisms is considerably reduced and consequently, there is a lower risk for decomposition of the principal ingredients of foodstuffs (Pavlov, 2007). Freezing, therefore is a much preferred technique to preserve food for long periods of time. Besides it does not require chemical agents or irradiation and so assures long-time shelf life (Campanone et al., 2006).
Frozen fish have become an important commodity both for domestic and export markets in a number of countries of the world (Al-Harbi and Uddin, 2005). Storage time and temperature are the major factors affecting the rate of loss of quality and the shelf life of fish (Einen et al., 2002; Arannilewa et al., 2005). Bacterial activity which depends on composition of the initial microflora related to the environment where the fish live and are caught, the seasonal period, the fishing method and the early handling, is by far the most important factor influencing fish quality (Al-Harbi and Uddin, 2005). Therefore, it is logical to use bacteria numbers as an index of quality (Suvanich et al., 2000; Al-Harbi and Uddin, 2005).
A freezing process is generally used to preserve quality of products by minimizing microbiological and chemical activites. Although the process may reduce bacterial populations in products to a certain degree, it is not often used to kill bacterial cells. Bacterial content and handling of raw materials, therefore, influence the bacteriological quality of frozen fish (Antony et al., 2002). Consequently, fish is one of the most perishable foods and difficult to handle (Al-Harbi and Uddin, 2005)....