Fish:Fish:

Classification:Classification:

Shape:Shape: Habitat:Habitat: Nutritive value:Nutritive value:

-Flat: sole and Flat: sole and plaiceplaice-Round: salmon Round: salmon and mackereland mackerel

-freshwater: freshwater: salmonsalmon- saltwater: saltwater: demersel fish demersel fish (swim at bottom (swim at bottom of sea) e.g. of sea) e.g. plaice, codplaice, cod-Pelagic fish Pelagic fish (near surface) (near surface) e.g.e.g.

-White fish: cod, White fish: cod, haddockhaddock-Oily fish: Oily fish: mackerel, mackerel, herring.herring.-Shellfish: Shellfish: mollusc – hard mollusc – hard shell e.g. shell e.g. musselsmussels

Mackerel, tuna.Mackerel, tuna.

- farmed: - farmed: salmon, trout salmon, trout and mackerel.and mackerel.

- crustaceans: - crustaceans: segmented segmented shells e.g. shells e.g. prawns, crabs.prawns, crabs.

Structure of fish:Structure of fish:

Refer to diagram on page 68Refer to diagram on page 68Fish is composed of fibresand connective Fish is composed of fibresand connective

tissue.tissue.The fibres are called myomeres (short and The fibres are called myomeres (short and

thick contain actin and myosin).thick contain actin and myosin).Layers of connective tissues (collagen) Layers of connective tissues (collagen)

hold fibres in place.hold fibres in place.Collagen converted to gelatine on cooking.Collagen converted to gelatine on cooking.

Composition of fish:Composition of fish:

White fish:White fish: Oily fish:Oily fish:

Protein: 17.5%Protein: 17.5%

Fat: 0.5%Fat: 0.5%

Carbohydrate: 0%Carbohydrate: 0%

Vitamins: BVitamins: B

Minerals: 1%Minerals: 1%

Water: 80%Water: 80%

Protein: 18%Protein: 18%

Fat: 15%Fat: 15%

Carbohydrate: 0%Carbohydrate: 0%

Vitamins: A, D, BVitamins: A, D, B

Minerals: 2%Minerals: 2%

Water: 65%Water: 65%

Shellfish:Shellfish:

Protein: 15%Protein: 15%

Fat: 2.5%Fat: 2.5%

Carbohydrate: 0%Carbohydrate: 0%

Vitamins: BVitamins: B

Minerals: 2%Minerals: 2%

Water: 79%Water: 79%

Nutritive value:Nutritive value:

Protein: HBV, 17 – 20% of protein, Protein: HBV, 17 – 20% of protein, Collagen, actin and myosin.Collagen, actin and myosin.

Fat: White fish is low compared to oily fish. Fat: White fish is low compared to oily fish. Unsaturated fat and omega 3 Unsaturated fat and omega 3 polyunsaturated fatty acids. polyunsaturated fatty acids.

Carbohydrate: Lacking so must be eaten Carbohydrate: Lacking so must be eaten with carbohydrate foods.with carbohydrate foods.

Vitamins: a lot of B vits. A and D in oily Vitamins: a lot of B vits. A and D in oily fish. Trace amount of vit C .fish. Trace amount of vit C .

Minerals: Calcium, Iodine, flourine, zinc Minerals: Calcium, Iodine, flourine, zinc and phosphorus. Shell fish contains iron. and phosphorus. Shell fish contains iron.

Water: low in kilocalories.Water: low in kilocalories.

Omega 3 polyunsaturated fatty Omega 3 polyunsaturated fatty acids:acids:

Present in oily fish.Present in oily fish.Eicosapentaenoic (EPA) and Eicosapentaenoic (EPA) and

docosahexaenoic (DHA) are essential fatty docosahexaenoic (DHA) are essential fatty acids.acids.

Reduce CHD, should be eaten at least Reduce CHD, should be eaten at least twice a week.twice a week.

Dietetic value of fish:Dietetic value of fish:

Unsaturated fat good for slimmers.Unsaturated fat good for slimmers.Reduce heart attacks as it contains omega Reduce heart attacks as it contains omega

3 polyunsaturated fatty acids.3 polyunsaturated fatty acids.Easily digestible for children, adults and Easily digestible for children, adults and

convalescents.convalescents. Inexpensive and tender when cooked.Inexpensive and tender when cooked.

Spoilage of fish:Spoilage of fish:

Oxidative rancidity: oils in fish react with Oxidative rancidity: oils in fish react with oxygen causing the fish to spoil.oxygen causing the fish to spoil.

Enzymes: enzymes remain active even at Enzymes: enzymes remain active even at low temp which affect the flesh.low temp which affect the flesh.

Bacterial action: fish is caught, it struggles. Bacterial action: fish is caught, it struggles. Uses up glycogen in muscle. No lactic acid Uses up glycogen in muscle. No lactic acid to preserve. Produces a smelling to preserve. Produces a smelling compound, trimethylamine.compound, trimethylamine.

Buying fish:Buying fish:

Buy when fresh (eyes bulging, glossy pink Buy when fresh (eyes bulging, glossy pink gills, moist skin with scales, elastic flesh, gills, moist skin with scales, elastic flesh, no smell).no smell).

Buy from a clean shop (on ice on display Buy from a clean shop (on ice on display stand).stand).

Buy in season.Buy in season.Choose medium sized fish for best flavour.Choose medium sized fish for best flavour.

Storing fish:Storing fish:

Bought when required and used Bought when required and used immediately.immediately.

Wrapping removed and rinsed under cold Wrapping removed and rinsed under cold water.water.

Covered and stored separately from other Covered and stored separately from other foods.foods.

Fish which requires more than one day Fish which requires more than one day should be frozen. White fish can be frozen should be frozen. White fish can be frozen up to 6 months and oily fish 3 months.up to 6 months and oily fish 3 months.

Processing fish:Processing fish:

Freezing:Freezing:

- cold temp inactivates microbes to - cold temp inactivates microbes to prevent spoilage.prevent spoilage.

- Blast frozen (fresh fish) at -30- Blast frozen (fresh fish) at -30ooC retains C retains the nutritive value of fish.the nutritive value of fish.

- White fish used within 6 months and oily - White fish used within 6 months and oily fish 3 months.fish 3 months.

Canning:Canning: salmon, sardines, tuna.salmon, sardines, tuna.Canned in oil or brine.Canned in oil or brine.Kills microbes and sealing prevents re entry of Kills microbes and sealing prevents re entry of

microbes.microbes.Vits A, D and calcium in canned fish.Vits A, D and calcium in canned fish.

Smoking:Smoking:Salmon, trout.Salmon, trout.Creosote and formaldehyde in smoke kills Creosote and formaldehyde in smoke kills

microbes. Fish is salted. Smoke is used from microbes. Fish is salted. Smoke is used from the smouldering wood chips. the smouldering wood chips.

Cold smoking, temp of 27oC the fish can be Cold smoking, temp of 27oC the fish can be further cooked e.g. haddock, herring.further cooked e.g. haddock, herring.

Hot smoking, temp can reach 80oC without Hot smoking, temp can reach 80oC without further cooking e.g. eel, mackerel.further cooking e.g. eel, mackerel.

Effects of cooking:Effects of cooking:

Microbes destroyed.Microbes destroyed.Protein coagulates.Protein coagulates.Collagen changes to gelatine on cooking.Collagen changes to gelatine on cooking.Loss of B vits.Loss of B vits.Overcooking leads to the fish being dry.Overcooking leads to the fish being dry.Vitamins and minerals dissolve into Vitamins and minerals dissolve into

cooking liquid.cooking liquid.

Filleting fish:Filleting fish:

Cut down the fish from head to tailCut down the fish from head to tailPare the fish away from ribs.Pare the fish away from ribs.Repeat.Repeat.

Skinning fish:Skinning fish:

Place fillet with skin downwards on board.Place fillet with skin downwards on board.Work knife between skin and flesh.Work knife between skin and flesh.Slide down to remove in one piece.Slide down to remove in one piece.

Methods of cooking fish:Methods of cooking fish:

Frying: shallow or deep. Fish should be Frying: shallow or deep. Fish should be coated to protect it and seal in flavour.coated to protect it and seal in flavour.

Grilling: Seals in flavour. Suitable for fillets Grilling: Seals in flavour. Suitable for fillets or small fish.or small fish.

Poaching: simmer fish in liquid.Poaching: simmer fish in liquid.Steaming: put fish in a steamer. Steaming: put fish in a steamer. Baking: whole fish or cutlets.Baking: whole fish or cutlets.Stewing: cook fish in a sauce.Stewing: cook fish in a sauce.

Microwave: suitable for fillets or cutlets. Microwave: suitable for fillets or cutlets. Rapid even cooking.Rapid even cooking.

Barbecuing: fillets usually wrapped in Barbecuing: fillets usually wrapped in tinfoil and seasoned to get a smoky tinfoil and seasoned to get a smoky flavour.flavour.

Refer to book pg. 73 for coatings.Refer to book pg. 73 for coatings.