by pdst not mine

1. FishFish
ClassificationClassification
WhiteWhite OilyOily ShellShell
Cod, WhitingCod, Whiting Salmon, TroutSalmon, Trout Prawns, CrabPrawns, Crab
Plaice, SolePlaice, Sole Tuna, HerringTuna, Herring Lobster, musselsLobster, mussels
Nutritive Value/CompositionNutritive Value/Composition
•ProteinProtein HBV, Easily digested. 17-20%HBV, Easily digested. 17-20%
•LipidLipid Polyunsaturated fatty acids, omega3 associated withPolyunsaturated fatty acids, omega3 associated with
lowering risk of heart disease. Oil in liver of white fish, in liverlowering risk of heart disease. Oil in liver of white fish, in liver
and fibres’ of oily fish. 0.5% white, 10-20% Oilyand fibres’ of oily fish. 0.5% white, 10-20% Oily
•CarbohydrateCarbohydrate None due to glycogen converted to lactic acidNone due to glycogen converted to lactic acid
during struggle when caught. Serve with rice/potatoesduring struggle when caught. Serve with rice/potatoes
•VitaminsVitamins B group in all and Vitamins A+D in oily fishB group in all and Vitamins A+D in oily fish
•MineralsMinerals Iodine, fluorine + iron. Calcium in bones of tinnedIodine, fluorine + iron. Calcium in bones of tinned
fish e.g. salmonfish e.g. salmon
•WaterWater High in white fish , less in shell + oily. 65-80%High in white fish , less in shell + oily. 65-80%
© PDST Home Economics

2. Dietetic ValueDietetic Value
• One or two portions should be eaten every week to help lowerOne 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 areare
important for brain development in unborn babiesimportant for brain development in unborn babies
and may help to alleviate skin problems and highand may help to alleviate skin problems and high
blood pressureblood pressure
• Easily digestedEasily digested suitable for children, elderly andsuitable for children, elderly and
invalidsinvalids
• Low in fatLow in fat so very suitable for low fat diets. White fishso very suitable for low fat diets. White fish
contains fat in the liver which is removed to makecontains fat in the liver which is removed to make
supplements..cod liver oil. Fat in oily fish gives it moresupplements..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 aMain source of HBV protein and B vitamins in the diet of a PescoPesco
vegetarian.vegetarian.
• Should beShould be eaten with rice/potatoeseaten with rice/potatoes as does not contain anyas does not contain any
carbohydratescarbohydrates

3. Spoilage of FishSpoilage 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 lefttheir stores of glycogen. There is no glycogen left
to be converted to lactic acid to preserveto be converted to lactic acid to preserve
the fishthe fish
• Bacteria multiply very quickly and break down the protein inBacteria multiply very quickly and break down the protein in
fish fleshfish 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 oxidativeFish also go off because of enzyme activity and oxidative
rancidityrancidity
• Polluted waters may contaminate shell fishPolluted waters may contaminate shell fish

4. • Fish is composed of bundles of short fibres calledFish is composed of bundles of short fibres called
myomers. These are held together by the connectivemyomers. These are held together by the connective
tissue called collagen.tissue called collagen.
• Collagen changes to gelatine during cooking, this allows theCollagen changes to gelatine during cooking, this allows the
fish fibres to fall apart.fish fibres to fall apart.
• As the fibres in fish are short the fish cooks very quicklyAs 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 areShell fish have coarser fibres so are
more difficult to digestmore difficult to digest
Cuts of fishCuts of fish
Fish can be sold whole, in fillets, steaksFish can be sold whole, in fillets, steaks
or cutletsor cutlets
Fish Structure

5. 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 ofFillets, 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

6. 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 thetaint 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 purchaseUse 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

7. Effects of Cooking on FishEffects of Cooking on Fish
• Protein coagulates and shrinks between 60Protein coagulates and shrinks between 60oo
C andC and
7070oo
C and flesh becomes opaqueC and flesh becomes opaque
• Fish shrinks slightlyFish shrinks slightly
• Fibres are short so the fish will cook quickly. TheFibres are short so the fish will cook quickly. The
connective tissue changes to gelatine making theconnective tissue changes to gelatine making the
fish break up easilyfish break up easily
• Some B Vitamins are lostSome B Vitamins are lost
• If the fish is cooked in water or milk this liquidIf the fish is cooked in water or milk this liquid
should be used for a sauce so that the leachedshould 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

8. ProcessingProcessing
• CanningCanning. Loss of B vitamins. Calcium available as the. Loss of B vitamins. Calcium available as the
bones are softened and edible. Can be canned in oilbones are softened and edible. Can be canned in oil
or brineor brine
• FreezingFreezing. Blast frozen at –30. Blast frozen at –30oo
C. Very little changeC. Very little change
in nutritive value. Can be processed intoin 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 30at 30oo
C or hot smoked at 110C or hot smoked at 110oo
C) orC) or
artificially (dyed and flavoured). Bacteria areartificially (dyed and flavoured). Bacteria are
destroyed, fish changes colour and a smokydestroyed, fish changes colour and a smoky
flavour developsflavour develops
Methods of CookingMethods of Cooking
Baking, frying, grilling, poaching,Baking, frying, grilling, poaching,
steaming, stewing and microwavingsteaming, stewing and microwaving