FishFishClassificationClassification

WhiteWhite OilyOily ShellShellCod, WhitingCod, Whiting Salmon, TroutSalmon, Trout Prawns, Crab Prawns, Crab

Plaice, SolePlaice, Sole Tuna, Herring Tuna, Herring Lobster, musselsLobster, musselsNutritive Value/CompositionNutritive Value/Composition

•ProteinProtein HBV, Easily digested. 17-20% HBV, Easily digested. 17-20%•LipidLipid Polyunsaturated fatty acids, omega3 associated Polyunsaturated fatty acids, omega3 associated with lowering risk of heart disease. Oil in liver of white with lowering risk of heart disease. Oil in liver of white fish, in liver and fibres’ of oily fish. 0.5% white, 10-20% fish, in liver and fibres’ of oily fish. 0.5% white, 10-20% OilyOily•CarbohydrateCarbohydrate None due to glycogen converted to lactic None due to glycogen converted to lactic acid during struggle when caught. Serve with acid during struggle when caught. Serve with rice/potatoesrice/potatoes•VitaminsVitamins B group in all and Vitamins A+D in oily fish B group in all and Vitamins A+D in oily fish•MineralsMinerals Iodine, fluorine + iron. Calcium in bones of Iodine, fluorine + iron. Calcium in bones of tinned fish e.g. salmontinned fish e.g. salmon•Water Water High in white fish , less in shell + oily. 65-80%High in white fish , less in shell + oily. 65-80%

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Dietetic ValueDietetic Value

• One or two portions should be eaten every week to help lower One or two portions should be eaten every week to help lower cholesterol and prevent heart attacks. cholesterol and prevent heart attacks. Omega 3 fatty acidsOmega 3 fatty acids are are important for brain development in unborn babies important for brain development in unborn babies and may help to alleviate skin problems and high and may help to alleviate skin problems and high blood pressure blood pressure

• Easily digestedEasily digested suitable for children, elderly and suitable for children, elderly and invalids invalids

• Low in fatLow in fat so very suitable for low fat diets. White fish so very suitable for low fat diets. White fish contains fat in the liver which is removed to make contains fat in the liver which is removed to make

supplements..cod liver oil. Fat in oily fish gives it more supplements..cod liver oil. Fat in oily fish gives it more flavour than white fish. 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 Main source of HBV protein and B vitamins in the diet of a PescoPesco vegetarian.vegetarian.• Should be Should be eaten with rice/potatoeseaten with rice/potatoes as does not contain any as does not contain any

carbohydratescarbohydrates

Spoilage of FishSpoilage of Fish

• When fish are caught they struggle and use up When fish are caught they struggle and use up

their stores of glycogen. There is no glycogen left their stores of glycogen. There is no glycogen left to be converted to lactic acid to preserve to be converted to lactic acid to preserve the fish the fish

• Bacteria multiply very quickly and break down the Bacteria multiply very quickly and break down the protein in fish flesh protein in fish flesh

• Protein is converted to a nitrogen compound ( tri-Protein is converted to a nitrogen compound ( tri-methylamine) which has a very strong smellmethylamine) which has a very strong smell

• Fish also go off because of enzyme activity and oxidative Fish also go off because of enzyme activity and oxidative rancidity rancidity

• Polluted waters may contaminate shell fishPolluted waters may contaminate shell fish

• Fish is composed of bundles of short fibres called Fish is composed of bundles of short fibres called myomers. These are held together by the connective myomers. These are held together by the connective tissue called collagen. tissue called collagen.

• Collagen changes to gelatine during cooking, this allows Collagen changes to gelatine during cooking, this allows the fish fibres to fall apart.the fish fibres to fall apart.

• As the fibres in fish are short the fish cooks very quickly As the fibres in fish are short the fish cooks very quickly and are very easy to digest.and are very easy to digest.

Shell fish have coarser fibres so are Shell fish have coarser fibres so are

more difficult to digest more difficult to digest Cuts of fishCuts of fish

Fish can be sold whole, in fillets, Fish can be sold whole, in fillets, steaks or cutletssteaks or cutlets

Fish Structure

Buying FishBuying Fish

Buy fish in season, they are better quality and cheapestBuy fish in season, they are better quality and cheapest Fish should smell freshFish should smell fresh Flesh should be firm and moistFlesh should be firm and moist Fillets, steaks and cutlets should show no sign of Fillets, steaks and cutlets should show no sign of

discolourationdiscolouration Medium size fish have a better flavour than large fishMedium size fish have a better flavour than large fish Colour should be correct for type of fishColour should be correct for type of fish Eyes should be bright and clearEyes should be bright and clear Molluscs should not be openMolluscs should not be open Frozen fish should be frozen solidFrozen fish should be frozen solid

StorageStorage

• Fish should be covered before beingFish should be covered before being

refrigerated. The odour from fish will quicklyrefrigerated. The odour from fish will quickly

taint other food e.g. egg/milk. Covering the taint other food e.g. egg/milk. Covering the fish will also prevent the fish from drying outfish 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 freezerFrozen fish should be placed into the freezer

immediatelyimmediately

• Tinned fish should be used up immediatelyTinned fish should be used up immediately

Effects of Cooking on FishEffects of Cooking on Fish

• Protein coagulates and shrinks between 60Protein coagulates and shrinks between 60ooC C and 70and 70ooC and flesh becomes opaqueC and flesh becomes opaque

• Fish shrinks slightlyFish shrinks slightly• Fibres are short so the fish will cook quickly. Fibres are short so the fish will cook quickly.

The connective tissue changes to gelatine The connective tissue changes to gelatine making the fish break up easilymaking 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 If the fish is cooked in water or milk this liquid

should be used for a sauce so that the leached should be used for a sauce so that the leached nutrients are not lostnutrients are not lost

• Bacteria and parasites are destroyedBacteria and parasites are destroyed

ProcessingProcessing• CanningCanning. Loss of B vitamins. Calcium available . Loss of B vitamins. Calcium available

as the bones are softened and edible. Can be as the bones are softened and edible. Can be canned in oil or brinecanned in oil or brine

• FreezingFreezing. Blast frozen at –30. Blast frozen at –30ooC. Very little C. Very little change in nutritive value. Can be processed into change in nutritive value. Can be processed into

fish fingers, fish in batter, etc.fish fingers, fish in batter, etc.• SmokingSmoking. Can be done naturally(cold smoked . Can be done naturally(cold smoked

at 30 at 30ooC or hot smoked at 110C or hot smoked at 110ooC) or C) or

artificially (dyed and flavoured). Bacteria are artificially (dyed and flavoured). Bacteria are destroyed, fish changes colour and a smoky destroyed, fish changes colour and a smoky flavour developsflavour develops

Methods of Methods of CookingCooking Baking, frying, grilling, poaching, Baking, frying, grilling, poaching, steaming, stewing and microwavingsteaming, stewing and microwaving