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Milk A near perfect food © PDST Home Economics % Composition of Milk 90 80 70 60 Whole milk Low fat milk Skimmed milk 50 40 30 20 10 0 Pro. Fat Carb. Water Nutritive/Food Value Protein: 3.5%, HBV, caseinogen, lactalbumin, lactoglobulin Carbohydrate: 4.5%, disaccharide lactose, lactic acid bacteria change lactose to lactic acid when milk goes sour Fat: 4%, saturated, in fine emulsion, easy to digest Minerals: calcium, 500mls of milk 100% of RDA, Phosphorus, trace of sodium and potassium Vitamins: good source vitamin A especially summer milk, also has some vitamin D, good source Vitamins B1 and B2, only trace Vitamin C Water 87% very dilute food therefore easy to digest Dietetic Value Easily digested nutrients, useful for invalids, elderly, infants. Assists growth - protein, Vitamin A, Calcium, Phosphorus, Vitamin D - good for children, adolescents and pregnant women. Due to saturated fat and cholesterol people on low cholesterol, low fat diets should use skimmed milk. Milk lacks fibre, Vitamin C, Iron so infants need other food in their diet after 6 months. Cheap food available in a variety of forms. Culinary Uses Drinks Sauces, white roux & custard Enriching dishes, soup, mash Milk based dessert, milk puddings, custard dishes In baking, bread, scones etc. Batters, pancake, coating, yorkshire pudding Glazing baked goods Effects of Heat on Milk Protein coagulates, forms skin, milk boils over Change of colour (caramelisation of lactose + maillard reaction) Change of flavour Loss of Vitamin B1 Micro-organisms killed Buying & Storing Check the best before date Store in fridge @ 2ºC Once opened use quickly Store in its own sterile carton, resealable carton best Don’t mix milk of different dates Use in rotation Away from strong smelling food Don’t expose to sunlight, destroys vitamin B2 Homogenised milk can be frozen for one month Processing Milk Homogenised: Means to make the same Heated to 60ºC, forced through tiny holes to break up fat globules Tiny globules stay spread through the milk Effect: Milk has smoother creamier taste Pasteurisation: Heated to 72ºC for 25 seconds then cooled quickly All pathogenic bacteria killed, safer Some souring bacteria killed, keeps better Processing Milk Ultra heat treatment(UHT): Long life milk Heated to 132ºC for 1 second Cooled quickly and sealed in sterile containers Effect: Kills all micro-organisms Milk keeps for several month unopened Destroys vitamin C & B group Change of flavour Processing Milk Evaporated milk:(e.g. Carnation) Pasteurised, evaporated to 50%, homogenised Sealed in tins and heated to 115 ºC for 20 min Keeps indefinitely Vitamins B & C lost Flavour change Not suitable for children Condensed milk:(e.g. Nestle) Pasteurised, evaporated to 33%, homogenised, 40% sugar added. Sealed in tins, heated 115 for 15min Vitamins B & C lost High in calories Processing Milk Dehydrated milk (Marvel) Homogenised, evaporated to 60%, then spray dried or roller dried Handy in emergencies or when camping Reconstituted with water Flavour changed Vitamins and some amino acids lost Safety of Milk Milk is ideal place for bacteria to grow Controls inspection and testing of herds for TB etc. Registration of farms Guidelines for milking, transportation, bottling & storage of milk Sampling of raw milk for bacterial contamination Pasteurisation of milk for human consumption Controlled by Milk and Dairy Acts and Food and Drugs Acts Classification of Milk Whole milk - 4% fat Low fat (semi-skimmed) - 1.5% fat Skimmed - 0.1% fat Fortified ‘supermilk’ low fat with extra vitamins and minerals added Soya made from soya beans suitable for vegans & those allergic to cows milk Buttermilk, soured by lactic acid bacteria, for baking