Chapter 1 Separation processes-an overview A S GRANDISON and M. J. LEWIS, Department of Food Science and Technology, The University of Reading, Whiteknights, PO Box 226, Reading, RG6 6AP 1.1 FOODS- THE RAW MATERIAL Food and drink play a vital role in all our lives, providing us with the nutrients essential for all our daily activities, including cell maintenance, growth and reproduction Although foods are commonplace and much taken for granted, their composition and tructure are by no means simple. Firstly, all foods are chemical in nature. For most foods the principal component is water and this water plays an important role in the overall behaviour of that food. One of the most important branches of separation is the removal of water, to save transportation costs and improve microbial stability The other components can be classified into major components, such as protein, fat or lipid, sugars, starch and fibre. The minor components include the minerals, which are known collectively as ash, vitamins and organic acids. Information on food composition and the amounts of major and minor components can be found in the Composition of Foods Tables(Paul and Southgate, 1978). Table 1. I illustrates just some of the compo- sition data that is available for a selection of food Food composition tables are useful in that they provide an average composition However, some of their limitations are illustrated below. taking milk as an example. It be noted that similar points could be made about most oth Milk is extremely complex in terms of its chemical composition, containing protein fat, carbohydrate, minerals and vitamins. There are many different proteins, which can be subdivided into the whey proteins, which are in true solution in the aqueous phase, and the caseins, which are in the colloidal form. The fat itself is a complex mixture of triglycerides and, being immiscible with water, is dispersed as small droplets, stabilised by a membrane, within the milk. The vitamins are classified as water or fat soluble, depending on which phase they most associate with. Some of the minerals, such as calcium and phosphorus, partition between the aqueous phase and the colloidal casein and play a major role in the stability of the colloidal dispersion. In addition, there are many other components present in trace amounts, which may affect its delicate flavourChapter 1 Separation processes - an overview A. S. GRANDISON and M. J. LEWIS, Department of Food Science and Technology, The University of Reading, Whiteknights, PO Box 226, Reading, RG6 6AP 1.1 FOODS - THE RAW MATERIAL Food and drink play a vital role in all our lives, providing us with the nutrients essential for all our daily activities, including cell maintenance, growth and reproduction. Although foods are commonplace and much taken for granted, their composition and structure are by no means simple. Firstly, all foods are chemical in nature. For most foods the principal component is water and this water plays an important role in the overall behaviotir of that food. One of the most important branches of separation is the removal of water, to save transportation costs and improve microbial stability. The other components can be classified into major components, such as protein, fat or lipid, sugars, starch and fibre. The minor components include the minerals, which are known collectively as ash, vitamins and organic acids. Information on food composition and the amounts of major and minor components can be found in the Composition of Foods Tables (Paul and Southgate, 1978). Table 1.1. illustrates just some of the compo￾sition data that is available, for a selection of foods. Food composition tables are useful in that they provide an average composition. However, some of their limitations are illtistrated below, taking milk as an example. It should be noted that similar points could be made about most other foods. Milk is extremely complex in terms of its chemical composition, containing protein, fat, carbohydrate, minerals and vitamins. There are many different proteins, which can be subdivided into the whey proteins, which are in true solution in the aqueous phase, and the caseins, which are in the colloidal form. The fat itself is a complex mixture of triglycerides and, being immiscible with water, is dispersed as small droplets, stabilised by a membrane, within the milk. The vitamins are classified as water or fat soluble, depending on which phase they most associate with. Some of the minerals, such as calcium and phosphorus, partition between the aqueous phase and the colloidal casein and play a major role in the stability of the colloidal dispersion. In addition, there are many other components present in trace amounts, which may affect its delicate flavour