Pasteurized Fish Products

Pasteurized fish products made of fresh, deep-frozen or frozen fish or fish portions have shelf lives, even without cold storage, of at least 6 months. These products are prepared by prolonged heat treatment of fish at temperatures below 100 °C. They are then tightly sealed in a container. Such products are salted or soaked in vinegar prior to pasteurization. 

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In meat curing, nitrite is traditionally used for developing the pink, heat-stable pigment. Its other important role is the inhibition of the outgrowth of Clostridium botulinum spores in pasteurized products and, in some countries, in several types of smoked fish. Nitrite also serves as an antioxidant and contributes positively to the development of the flavor of cured-meat. The undesirable side-effect, however, is the reaction of nitrite with amino groups of food constituents, leading to the formation of NNCs. 

HPhe irradiation of fishery products covers a broad area and includes microbiological, biochemical, organoleptic, and engineering problems in the field of fishery technology. Many advances have been made in recent years in the radiation pasteurization of fish and shellfish. 

Eleven, thirteen and twenty alkylbenzenes were identified among the volatiles in the boiled crayfish tail meat, hepato-pancreas and the pasteurized crahmeat, respectively. The alkylbenzenes and the naphthalenes might have come from environmental pollutants. Lee et al. (30) reported rapid uptake of naphthalene in marine fish. Several chlorobenzenes identified in the crayfish and crafcmeat samples possibly were degradation products of various pesticides. Neff et al. (29) reported that aromatic hydrocarbons accumulated in fish to a greater extent and were retained longer than the alkanes. Phenol was also identified in all three samples. The medicinal odor of phenol contributed negatively to these products. KUbota et al. (28) identified xylenes and phenol as volatile components that contributed undesirable odors to cooked krill. 

Sources. Only bacteria can synthesize vitamin B12. Vitamin B12 is present in animal products such as meat, poultry, fish (including shellfish), and to a lesser extent milk, but it is not generally present in plant products or yeast. Fresh pasteurized milk contains 0.9 p.g per cup and is an important source of vitamin B12 for some vegetarians. Those vegetarians who eat no animal products need supplemental vitamin B12 to meet their requirements. 

Lower dose treatments, often referred to as pasteurization doses, have shown much more promise. In particular, doses sufficiently low to cause no significant odor and flavor change in the food are adequate to eliminate the hazards to health associated with salmonella and nematode contamination. For example, the irradiation of frozen meat, whole egg and egg products used in baking, and high protein animal foodstuffs is under active investigation as a means of elimination of salmonellae. At the moment, however, this cannot be classed as an industrial application, since only a few tons have been irradiated in pilot experiments.The shelf-life of white fish kept on ice has been considerably extended by small doses of radiation, and in the United States a full-scale plant for the irradiation of fish has recently been completed. Fish remain an underused protein resource available for the underdeveloped countries, and a big expansion in fish consumption is likely if the world s protein requirements are to be met. Inevitably, the development of fish resources must go hand in hand with satisfactory transportation in view of the relatively limited shelf-life... 

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