The Three Phases Of Milk

Milk is a three phase (polyphasic) secretion of the mammary glands. The three phases are an oil in water phase which consists of fat droplets/globules dispersed in whey, a colloidial suspension of proteins such as casein micelles, globular proteins, and lipoprotein particles and the third phase is the solution of soluble proteins, minerals, lactose, vitamins, and other components [15]. The main component of milk is water and compounds such as fat(3.9%), protein (3.3%), lactose (5%), and minerals (0.7%) [38]. Milk also contains vitamins (e.g., vitamins A and C), enzymes (e.g., lactoperoxidases (LP) and acid phosphatase), and somatic cells Ehret, H. J., Ducruet, V., Luciani, A., and Feigenbaum, A. (1994) Styrene and ethylbenzene migrationfrom polystyrene into dairy products by dynamic purge and trap chromatography, Journal of Food

Science 59: 990–992, 1001

Spoilage is term used to describe the deterioration of foods’ texture, colour, odour or flavour to the point where the foods are unsuitable for human consumption. A variety of factors are involved and are mainly physical

Water, soil, vegetation, and bedding material are frequent sources of contamination from the exterior of the udder with psychrotrophic bacteria frequently being associated with bedding material, untreated water, soil, and vegetation. Psychrotrophs comprise the largest percentage of bacteria in milk and cause spoilage at temperatures at or below 7˚C [14]. They also have the ability to produce heat stable extracellular and/ or intracellular hydrolytic enzymes (Causin, 1982; Chen et al., 2003). Many of these enzymes retain their activity even after the conventional heat treatment of milk. Furthermore, psychrotrophic bacteria are the most commonly isolated organisms which caused the spoilage of the heat treated milk and dairy products as the result of post-pasteurization contamination of the products (Larsen and Jørgensen, 1997; Eneroth et al.,