2 Classification of fish Classified by HabitatFresh water e.g. troutSalt water(a) Demersal e.g. cod(b) Pelagic e.g. herringFarmed e.g. musselsClassified byShapeRound e.g. codFlat e.g. plaiceNutritive ValueOily fish e.g. herring, mackerel, trout, salmonWhite fish e.g. cod, haddock, plaice, sole, whitingShellfishCrustaceans e.g. lobster, prawnMolluscs e.g. mussels oysters
4 Composition of fish Class Protein Fat Carb Vitamins Minerals Water Oily18%15%0%ADB2%Iodine, Iron, andCalcium if tinned65%Shell2.5%BIodine/Iron79%White17%1%80%
5 Nutritive value Protein: HBV, Actin, Myosin. Fat: white fish- none; oily fish- unsaturated + omega 3 fatty acids; shellfish, low fat, high cholesterol.Carbohydrate: none, serve with carbohydrate rich food.
6 Nutritive valueVitamins: B-group all fish; Vitamin C oysters only; Vitamins A&D oily fish + stored in liver of cod etc.Minerals: Iron in all fish but less than meat; Iodine in sea fish; calcium and phosphorus in canned fish and fish with edible bones e.g. sardinesWater: 65%-80% depends on type of fish
7 Dietetic value Versatile, tasty, quick to cook. HBV protein – healthy meat substitute especially teenagers, child, pregnant women.Unsaturated fat and omega 3 means its good for those with heart disease and high cholesterol.White fish low energy food good for low calorie diets.White fish easily digested therefore good for invalids and elderly .Iodine in sea fish prevents goitre.Nutritional convenience food when canned or frozen in breadcrumbs, batter or sauce.Lacks carbohydrates. and Vitamin C. Serve with starchy food and salad/vegetables.Dietetic value
8 Spoilage of fishFish is very perishable, must be cooked or processed as soon as possible after being caught. Spoilage is caused byOxidative Rancidity: oily fishEnzymes: cause deterioration even at low temperatureBacteria: fish struggle when caught, use up all glycogen in the cells, therefore no lactic acid forms to preserve the fish after death. When bacteria damage fish trimethylamine is formed giving a bad smell
9 Buying and storing fish Fresh and in seasonClean busy shopMedium sizeWhole, fillet, cutlets, steaks, tail pieceWhole : Eyes bulge, gills red, skin moist, flesh firm, sea smellShell: heavy, molluscs closed, crustaceans aliveFrozen: solid, sealed, expiry dateCanned: no leaks, bulges, dents or rust. Check dateSmoked: glossy, firm, smoky smell, date, if vacuum packed store unopened in fridge, pack should not be blown or damagedStoring - freshFridgeUnwrap, clean plate with ice , cover looselyUse within 1-2 daysStoring – frozenTake home in cooler bagPut into freezer quicklyUse before expiry dateIf beginning to thaw use right away, do not refreeze
10 Preserving and processing fish FreezingBlast -30ºC , cold temp stops microbes rotting the fish, retain colour, texture, taste nutrition, oily fish keeps for 3 months only due to rancidity. Some fish is coated or frozen in sauce.CanningSalmon, sardines, mackerel, tuna, anchovies. Canned in brine, oil or sauce. The heat used in canning destroys all microbes and enzymes and sealing prevents re-entry. Only canned fish have calcium. Vitamin B destroyed by canning.SmokingSalmon, trout, kippers, mackerel, crab. The chemicals creosote and formaldehyde in the smoke prevent microbial growth. Fish is salted, then cold 27 ºC (raw) or hot 80 ºC need no more cooking. Gives flavour, colour sheen increases sodium.Preserving and processing fish
11 Cooking fish Effects of cooking Microbes & parasites destroyed. Protein coagulates and shrinksCollagen changes to gelatine fish flakes fall apartFlesh becomes opaqueLoss of Vitamin BMinerals and vitamins dissolve into cooking liquidOvercooked…dry and toughRulesFreshWash and dry well before cookingCooks quicklyGentle cooking…breaks apart
12 Cooking fish continued Methods:Frying, grilling, poaching, steaming, baking, stewing, barbecuing, microwaveCoatings:Flour, egg + breadcrumbs, oatmeal, batterSauces:Parsley, hollandaise, tartare, tomato, cheese, Marie RoseGarnishes:Lemon, parsley, cucumber, tomato lilies, peas
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