Bøger af Soottawat Benjakul

Lipid oxidation is one of the key problems associated with the loss of quality of seafood. In the seafood industry, lipid oxidation is a serious problem, not only because it produce rancid odors and flavors, decreases shelf life and alter texture and appearance of foods, but also because it can decrease the nutritional quality and safety of seafood. It is the process by which oxygen reacts with unsaturated lipids present in the foodstuff. In the presence of an initiator, polyunsaturated fatty acids can become oxidized and form alkyl radicals. When exposed to oxygen, the alkyl radicals rapidly form peroxyl radicals and these radicals can react with more lipids to produce hydroperoxides. As a lipid hydroperoxide decomposes, it forms numerous volatile compounds such as hexanal and propanal, which impact the sensory quality of foods. Lipid oxidation in seafood can be mediated by enzymes like lipoxygenase, cycloxygenase and haem protein like haemoglobin and myoglobin. Oxidation of lipids is accentuated in the immediate post-slaughter period, during handling, processing, storage and cooking. This process leads to discoloration, off-odor and off-flavor development.

Spoilage caused by the chemical reactions and microorganisms are principal cause of quality losses of fish and fish products during handling, processing and storage. Development of rancid odours and unpleasant flavours, changes of colour and texture as well as lowering nutritional value in fish can be prevented by selective natural additives. Due to the potential health hazards of synthetic additives currently used, natural additives, especially polyphenolic compounds have been intensively searched as the safe alternatives. Polyphenols (PP) are the natural antioxidants prevalent in fruits, vegetables, beverages (tea, wine, juices), plants, seaweeds and some herbs and show the antioxidative and antimicrobial activity in different fish and fish products. The use of polyphenolic compounds also appears to be a good alternative for sulphiting agent for retardation of melanosis in crustaceans. Phenolic compounds as the processing aid for textural modification of fish mince and surimi has also been successfully implemented. They have been proved to be the potential additives to prevent the quality deterioration or to improve the quality of fish and fish products.