Fish Classification WhiteOilyShell Cod, WhitingSalmon, Trout Prawns, Crab Plaice, SoleTuna, Herring Lobster, mussels Nutritive Value/Composition Protein HBV, Easily digested %Protein HBV, Easily digested % Lipid Polyunsaturated fatty acids, omega3 associated with lowering risk of heart disease. Oil in liver of white fish, in liver and fibres’ of oily fish. 0.5% white, 10-20% OilyLipid Polyunsaturated fatty acids, omega3 associated with lowering risk of heart disease. Oil in liver of white fish, in liver and fibres’ of oily fish. 0.5% white, 10-20% Oily Carbohydrate None due to glycogen converted to lactic acid during struggle when caught. Serve with rice/potatoesCarbohydrate None due to glycogen converted to lactic acid during struggle when caught. Serve with rice/potatoes Vitamins B group in all and Vitamins A+D in oily fishVitamins B group in all and Vitamins A+D in oily fish Minerals Iodine, fluorine + iron. Calcium in bones of tinned fish e.g. salmonMinerals Iodine, fluorine + iron. Calcium in bones of tinned fish e.g. salmon Water High in white fish, less in shell + oily %Water High in white fish, less in shell + oily % © PDST Home Economics

Dietetic Value Dietetic Value One or two portions should be eaten every week to help lower cholesterol and prevent heart attacks. Omega 3 fatty acids are important for brain development in unborn babies and may help to alleviate skin problems and high blood pressureOne or two portions should be eaten every week to help lower cholesterol and prevent heart attacks. Omega 3 fatty acids are important for brain development in unborn babies and may help to alleviate skin problems and high blood pressure Easily digested suitable for children, elderly and invalidsEasily digested suitable for children, elderly and invalids Low in fat so very suitable for low fat diets. White fish contains fat in the liver which is removed to makeLow in fat so very suitable for low fat diets. White fish contains fat in the liver which is removed to make supplements..cod liver oil. Fat in oily fish gives it more flavour than white fish. supplements..cod liver oil. Fat in oily fish gives it more flavour than white fish. Good substitute for meat and is high in HBV proteinsGood substitute for meat and is high in HBV proteins Main source of HBV protein and B vitamins in the diet of a Pesco Main source of HBV protein and B vitamins in the diet of a Pesco vegetarian. vegetarian. Should be eaten with rice/potatoes as does not contain any carbohydratesShould be eaten with rice/potatoes as does not contain any carbohydrates

Spoilage of Fish Spoilage of Fish When fish are caught they struggle and use upWhen fish are caught they struggle and use up their stores of glycogen. There is no glycogen left to be converted to lactic acid to preserve the fish their stores of glycogen. There is no glycogen left to be converted to lactic acid to preserve the fish Bacteria multiply very quickly and break down the protein in fish fleshBacteria multiply very quickly and break down the protein in fish flesh Protein is converted to a nitrogen compound ( tri- methylamine) which has a very strong smellProtein is converted to a nitrogen compound ( tri- methylamine) which has a very strong smell Fish also go off because of enzyme activity and oxidative rancidityFish also go off because of enzyme activity and oxidative rancidity Polluted waters may contaminate shell fishPolluted waters may contaminate shell fish

Fish is composed of bundles of short fibres called myomers. These are held together by the connective tissue called collagen.Fish is composed of bundles of short fibres called myomers. These are held together by the connective tissue called collagen. Collagen changes to gelatine during cooking, this allows the fish fibres to fall apart.Collagen changes to gelatine during cooking, this allows the fish fibres to fall apart. As the fibres in fish are short the fish cooks very quickly and are very easy to digest.As the fibres in fish are short the fish cooks very quickly and are very easy to digest. Shell fish have coarser fibres so are Shell fish have coarser fibres so are more difficult to digest Cuts of fish more difficult to digest Cuts of fish Fish can be sold whole, in fillets, steaks or cutlets Fish can be sold whole, in fillets, steaks or cutlets Fish Structure

Buying Fish  Buy fish in season, they are better quality and cheapest  Fish should smell fresh  Flesh should be firm and moist  Fillets, steaks and cutlets should show no sign of discolouration  Medium size fish have a better flavour than large fish  Colour should be correct for type of fish  Eyes should be bright and clear  Molluscs should not be open  Frozen fish should be frozen solid

Storage Storage Fish should be covered before being Fish should be covered before being refrigerated. The odour from fish will quickly taint other food e.g. egg/milk. Covering the fish will also prevent the fish from drying out Use fish on the day of purchase Use fish on the day of purchase Frozen fish should be placed into the freezer Frozen fish should be placed into the freezerimmediately Tinned fish should be used up immediately Tinned fish should be used up immediately

Effects of Cooking on Fish Protein coagulates and shrinks between 60 o C and 70 o C and flesh becomes opaqueProtein coagulates and shrinks between 60 o C and 70 o C and flesh becomes opaque Fish shrinks slightlyFish shrinks slightly Fibres are short so the fish will cook quickly. The connective tissue changes to gelatine making the fish break up easilyFibres are short so the fish will cook quickly. The connective tissue changes to gelatine making the fish break up easily Some B Vitamins are lostSome B Vitamins are lost If the fish is cooked in water or milk this liquid should be used for a sauce so that the leached nutrients are not lostIf the fish is cooked in water or milk this liquid should be used for a sauce so that the leached nutrients are not lost Bacteria and parasites are destroyedBacteria and parasites are destroyed

Processing Processing Canning. Loss of B vitamins. Calcium available as the bones are softened and edible. Can be canned in oil or brineCanning. Loss of B vitamins. Calcium available as the bones are softened and edible. Can be canned in oil or brine Freezing. Blast frozen at –30 o C. Very little change in nutritive value. Can be processed intoFreezing. Blast frozen at –30 o C. Very little change in nutritive value. Can be processed into fish fingers, fish in batter, etc. fish fingers, fish in batter, etc. Smoking. Can be done naturally(cold smoked at 30 o C or hot smoked at 110 o C) orSmoking. Can be done naturally(cold smoked at 30 o C or hot smoked at 110 o C) or artificially (dyed and flavoured). Bacteria are destroyed, fish changes colour and a smoky flavour develops artificially (dyed and flavoured). Bacteria are destroyed, fish changes colour and a smoky flavour develops Methods of Cooking Methods of Cooking Baking, frying, grilling, poaching, steaming, stewing and microwaving Baking, frying, grilling, poaching, steaming, stewing and microwaving