1. Fish:

2. Classification: Shape: Habitat: Nutritive value: Flat: sole and plaice
Round: salmon and mackerel
freshwater: salmon
saltwater: demersel fish (swim at bottom of sea) e.g. plaice, cod
Pelagic fish (near surface) e.g.
White fish: cod, haddock
Oily fish: mackerel, herring.
Shellfish: mollusc – hard shell e.g. mussels

3. Mackerel, tuna.
- farmed: salmon, trout and mackerel.
- crustaceans: segmented shells e.g. prawns, crabs.

4. Structure of fish: Refer to diagram on page 68
Fish is composed of fibresand connective tissue.
The fibres are called myomeres (short and thick contain actin and myosin).
Layers of connective tissues (collagen) hold fibres in place.
Collagen converted to gelatine on cooking.

5. Composition of fish: White fish: Oily fish: Protein: 17.5% Fat: 0.5%
Carbohydrate: 0%
Vitamins: B
Minerals: 1%
Water: 80%
Protein: 18%
Fat: 15%
Vitamins: A, D, B
Minerals: 2%
Water: 65%

6. Shellfish:
Protein: 15%
Fat: 2.5%
Carbohydrate: 0%
Vitamins: B
Minerals: 2%
Water: 79%

7. Nutritive value:
Protein: HBV, 17 – 20% of protein, Collagen, actin and myosin.
Fat: White fish is low compared to oily fish. Unsaturated fat and omega 3 polyunsaturated fatty acids.
Carbohydrate: Lacking so must be eaten with carbohydrate foods.
Vitamins: a lot of B vits. A and D in oily fish. Trace amount of vit C .

8. Minerals: Calcium, Iodine, flourine, zinc and phosphorus
Minerals: Calcium, Iodine, flourine, zinc and phosphorus. Shell fish contains iron.
Water: low in kilocalories.

9. Omega 3 polyunsaturated fatty acids:
Present in oily fish.
Eicosapentaenoic (EPA) and docosahexaenoic (DHA) are essential fatty acids.
Reduce CHD, should be eaten at least twice a week.

10. Dietetic value of fish:
Unsaturated fat good for slimmers.
Reduce heart attacks as it contains omega 3 polyunsaturated fatty acids.
Easily digestible for children, adults and convalescents.
Inexpensive and tender when cooked.

11. Spoilage of fish:
Oxidative rancidity: oils in fish react with oxygen causing the fish to spoil.
Enzymes: enzymes remain active even at low temp which affect the flesh.
Bacterial action: fish is caught, it struggles. Uses up glycogen in muscle. No lactic acid to preserve. Produces a smelling compound, trimethylamine.

12. Buying fish:
Buy when fresh (eyes bulging, glossy pink gills, moist skin with scales, elastic flesh, no smell).
Buy from a clean shop (on ice on display stand).
Buy in season.
Choose medium sized fish for best flavour.

13. Storing fish: Bought when required and used immediately.
Wrapping removed and rinsed under cold water.
Covered and stored separately from other foods.
Fish which requires more than one day should be frozen. White fish can be frozen up to 6 months and oily fish 3 months.

14. Processing fish: Freezing:
- cold temp inactivates microbes to prevent spoilage.
- Blast frozen (fresh fish) at -30oC retains the nutritive value of fish.
- White fish used within 6 months and oily fish 3 months.

15. Canning: salmon, sardines, tuna. Canned in oil or brine.
Kills microbes and sealing prevents re entry of microbes.
Vits A, D and calcium in canned fish.

16. Smoking:
Salmon, trout.
Creosote and formaldehyde in smoke kills microbes. Fish is salted. Smoke is used from the smouldering wood chips.
Cold smoking, temp of 27oC the fish can be further cooked e.g. haddock, herring.
Hot smoking, temp can reach 80oC without further cooking e.g. eel, mackerel.

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

18. Filleting fish: Cut down the fish from head to tail
Pare the fish away from ribs.
Repeat.

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

20. Methods of cooking fish:
Frying: shallow or deep. Fish should be coated to protect it and seal in flavour.
Grilling: Seals in flavour. Suitable for fillets or small fish.
Poaching: simmer fish in liquid.
Steaming: put fish in a steamer.
Baking: whole fish or cutlets.
Stewing: cook fish in a sauce.

21. Microwave: suitable for fillets or cutlets. Rapid even cooking.
Barbecuing: fillets usually wrapped in tinfoil and seasoned to get a smoky flavour.
Refer to book pg. 73 for coatings.