The protein is in the form of both casein micelles, which are themselves colloidal particles, and free in solution as whey protein. The emulsion is composed of fat droplets dispersed in an aqueous phase containing protein. Table 7.1 gives the composition of whole cow's milk. Milk is a complex food emulsion and colloidal sol. Not only is milk a very nutritious food in its own right, but it is also a very versatile starting point for many other dairy products.
A brief description of their production will be given where relevant, with emphasis on the role that emulsifiers play in the formation and stability of the product.Ībstract = "Bovine milk has been an important source of food for human beings for thousands of years. In the following pages, the major emulsifier-containing dairy and imitation dairy products will be reviewed. One of the most versatile of these additives are the low molecular weight emulsifiers. To control the structure and stability of these products, the manufacturer can add a range of permitted additives that can be either naturally occurring or artificial. The contribution that they make to the stability of the milk fat globule is not well understood, but their use as food-grade emulsifiers has been the subject of extensive fundamental research (Courthaudon et al., 1991 Dickinson et al., 1993a Dickinson & Iveson, 1993). Phospholipids are important food emulsifiers in their own right. The phospholipid fraction of the membrane is composed of lecithin, phosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositide, plasmalogens and sphingomyelin. The average composition of the MFGM has been estimated to be about 48% protein, 33% phospholipid, and 11% water, with the remainder made up of other minor lipid components (Walstra & Jenness, 1984). The fat droplets are stabilized by an adsorbed layer of protein and phospholipid called the 'milk fat globule membrane' (MFGM), which is distinct from the aqueous phase protein (Walstra & Jenness, 1984). A considerable reserve of knowledge has been assembled on the structure and properties of milk proteins (Swaisgood, 1992). Bovine milk has been an important source of food for human beings for thousands of years.
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