【正文】 ty Fats do not melt immediately, but soften over a range of temperatures. This property is called plasticity, and gives each fat its unique character. The plasticity is due to the mixture of triglycerides, each with its own melting point. Some fats have been formulated so that their melting points are low and they can be spread straight from the fridge, eg soft margarine. (3) Flavour All fats and oils have unique flavours and odours. Some are more suited for particular purposes than others, eg olive oil for salad dressing (for flavour) and lard for pastry (due to its blandness). (4) Retention of moisture Some fats can help retain a bakery product’s moisture and increase its shelflife. They may also be used to baste food being cooked by dry heat. Storage Fats should be stored in a cool place, covered, and away from strong odours. They should be packaged to prevent oxidation. Oils should be stored at ambient temperature in sealed containers. Oils that have been used need to be strained to remove impurities to prevent oxidation. Oils that have been used for deep frying frequently, should be discarded. 5. Meat Beef/Veal, eg rump steak, brisket, loin of veal Lamb/Mutton,eg chops, shoulder, shank Pork/Bacon, eg chops, gammon steak, spare ribs Poultry, eg chicken, duck, goose Offal, eg liver, kidney, tripe Game, eg pheasant, rabbit, venison Types Composition Meat is muscle tissup from long thin muscle fibres. These are bound together in bundles by thin sheets of connective tissue. Connective tissue is made up from basic proteins collagen, elastin and reticulin. Each protein has specific characteristics and reacts differently when meat is cooked. Collagen is weakened by heat and forms gelatin, which is soluble. This change helps the meat to bee tender. The two other proteins are not weakened by heat, yet provide elasticity and strength. Characteristic (1) Tenderness: Some varieties of meat are tough and may be hard to cut or chew. Reasons for this include the type of animal, its age, level of activity and the part of the animal eaten. Tenderness can be improved by: 1) Mechanical action: reducing the length of muscle fibres, for example by mincing, hitting with a tenderising hammer or cutting the meat into chunks. 2) Chemical action: Meat tenderizers contain proteolytic enzymes which, when added to the surface of meat, digest muscle fibre and connective tissue. 3) Hydration: An acidic, alkaline or salt solution can increase the water holding capacity of meat and make it more tender. Acids, eg wine or lemon juice, are often used to marinade meat before cooking. (2) Colour change: The colour of meat is due to a mixture of pigment in the muscle. The main pigment is called myoglobin. Muscles contain varying proportions of pigments. Muscles which are used for physical activity contain large quantities and are darker in colour. As red meat is cooked the myoglobin changes from a purple red to a greyish brown in colour. Nutrition Lean meat is a nutritious food, which in moderate amounts can make a valuable contribution to intakes of protein, long chain fatty acids, B vitamins, vitamin D, iron and zinc. Protein: 1020% Fat: lean % (pork), % (beef ) Fat: 90% Minerals: %, Ca , Fe (heme) Meat Nutrition in 100g Protein (g) Fat (mg) Ca (mg) Fe (mg) A (ug) B1 (mg) B2 (mg) Ch (mg) Pork 6 44 79 Chicken 9 48 106 Pig heart 12 13 151 Duck 6 52 94 Goose 4 42 74 幾種畜肉和禽肉主要營養(yǎng)素含量 食物名稱 蛋白質(zhì) g/100g 脂肪g/100g 硫胺素mg/100g 核黃素mg/100g 尼克酸mg/100g 視黃醇μg/100g Fe mg/100g 豬里脊 5 豬排骨肉 10 豬肝 4972 牛后腿 2 羊后腿 8 兔肉 212 雞胸脯肉 16 雞肝 10414 鵪鶉 40 鴨 52 鴨血 鵝 42 6. Milk and milk product Milk Cows’ milk is the type of milk most monly consumed. Other types that are also used are ewes’ and goats’ milk. Most milk undergoes some form of heat processing such as pasteurisation, sterilisation or ultra high temperature (UHT) treatment. This is to ensure that any harmful microanisms are destroyed before the milk is consumed and to imp