2 A. S. Grandison and M.J. Lewis Table 1. 1 Composition of foods(weight/100 g) Milk Apple Peas Flour Beef water(g) 87.6(878)85.678.513.074.0 82.1 protein (g fat(g) 38(3.9) tr 1.2 gar(g 1.7 0.0 0.0 starch(g) 00(0.0 6.678.4 fibre(g) 0.0(0.0) 5.2 potassium(mg) sodium (mg 50(55) 6 iron(mg) 0.05(006)0.3 95(92 6 130 180 170 vitamin C(mg) vitamin BI(mg) 0.04(0.06)0.040.320.330.07008 vitamin B6(mg) 0.04(0.06)0.030.160.150.32 033 vitamin D(ug) 0.03(0.03) vitamin E (mg) 0.10(0.09)0.2tr 0.15 0.44 flour- household pla These values are taken from Paul and Southgate (1978). Figures in parentheses are for milk, taken from MeCance and widdowson's Composition of Foods Tables (Sth edn)(1991), Royal Society of Chemistry. MAFF. There are slight differences between the reported results and processing characteristics and nutritional value, such as trace minerals, organic acids and non-protein nitrogen compounds such as peptides, urea and amino acids. Walstra and Jenness(1984)have listed over 60 components present in milk, at levels that can be readily detected. Milk is also potentially a very unstable material. For example the pro- tein can be made to coagulate by a variety of methods, including heating, addition of the enzyme rennet, acid, salts and ethanol. Also the fat globules rise to the surface under the influence of gravity Superimposed on this complex composition is the fact that it is subject to wide variation, Milks from different species differ markedly, and many types of milk other than cows are consumed worldwide, e.g. sheep, goat, buffalo, camel. Within the same pecies there are large differences between breeds, and even between individual animals in the same herd. In addition to this, and of prime importance to the milk-processing industry, milk from the same animals is subject to wide seasonal variation, reflecting the change in the animals'diet throughout the year, and the stage of lactation. Factors relating to the handling of milk, such as the pH or the amount of dissolved oxygen, are also important to its stability Foods may also be contaminated with matter from their production environment, i.e soil, water and farmyard. For example milk may be contaminated with dirt, straw, anti biotics, growth hormones, heavy metals, or radionuclides2 A. S. Grandison and M. J. Lewis Table 1.1. Composition of foods (weight/100 g) Milk Apple Peas Flour Beef Cod water (g) 87.6 (87.8) 85.6 78.5 13.0 74.0 82.1 protein (g) 3.3 ( 3.2) 0.3 5.8 9.8 20.3 17.4 fat (€9 3.8 ( 3.9) tr. 0.4 1.2 4.6 0.7 starch (g) 0.0 ( 0.0) 0.4 6.6 78.4 - sugar (g) 4.7 ( 4.8) 9.2 4.0 1.7 0.0 0.0 fibre (8) 0.0 ( 0.0) 2.4 5.2 3.4 - sodium (mg) 50( 55) 2 1 2 61 77 - potassium (mg) 150(140) 120 340 140 350 320 calcium (mg) 120 (1 15) 4 15 150 7 16 iron (mg) 0.05 (0.06) 0.3 1.9 2.2 2.1 0.3 phosphorus (mg) 95 ( 92) 16 100 130 180 170 vitamin C (mg) 1.50 (1.0) 15 25 vitamin B 1 (mg) 0.04 (0.06) 0.04 0.32 0.33 0.07 0.08 vitamin B6 (mg) 0.04 (0.06) 0.03 0.16 0.15 0.32 0.33 - - - vitamin D (ug) 0.03 (0.03) - - - tr tr vitamin E (mg) 0.10 (0.09) 0.2 tr tr 0.15 0.44 * flour - household plain tr - trace These values are taken from Paul and Southgate (1978). Figures in parentheses are for milk, taken from McCance and Widdowson’s Coniposiiion of Foods Tables (5th edn) (1991), Royal Society of Chemistry, MAFF. There are slight differences between the reported results. and processing characteristics and nutritional value, such as trace minerals, organic acids and non-protein nitrogen compounds such as peptides, urea and amino acids. Walstra and Jenness (1984) have listed over 60 components present in milk, at levels that can be readily detected. Milk is also potentially a very unstable material. For example the pro￾tein can be made to coagulate by a variety of methods, including heating, addition of the enzyme rennet, acid, salts and ethanol. Also the fat globules rise to the surface under the influence of gravity. Superimposed on this complex composition is the fact that it is subject to wide variation. Milks from different species differ markedly, and many types of milk other than cow’s are consumed worldwide, e.g. sheep, goat, buffalo, camel. Within the same species there are large differences between breeds, and even between individual animals in the same herd. In addition to this, and of prime importance to the milk-processing industry, milk from the same animals is subject to wide seasonal variation, reflecting the change in the animals’ diet throughout the year, and the stage of lactation. Factors relating to the handling of milk, such as the pH or the amount of dissolved oxygen, are also important to its stability. Foods may also be contaminated with matter from their production environment, i.e. soil, water and farmyard. For example milk may be contaminated with dirt, straw, anti￾biotics, growth hormones, heavy metals, or radionuclides