ABSTRACT
Collected from Local Farms .............................................................404 15.6 Summary and Conclusions ...........................................................................405 Acknowledgments ..................................................................................................405 References ..............................................................................................................406
The physical characteristics of milk are highly complex, as milk is composed of an intricate mixture of fat globules and protein (casein, whey) in an aqueous solution of lactose, minerals, and other minor constituents. Milk’s physical characteristics are affected by several factors, including the composition and processing of milk. Measurement of milk’s physical properties is used in processing, to determine the concentration of milk’s components, and to evaluate the quality of milk products. Lactose is the major carbohydrate in milk. Measurement of lactose in milk is important because it contributes to the sensory and functional properties of milk. Lactose (β-d-galactopyranosyl-(1 → 4)-d-glucose) is a disaccharide sugar that is found most notably in cow milk (but is in higher concentration in human milk, and is also found in those of other mammals) and is formed from galactose and glucose. Lactose (Figure 15.1) was discovered in milk in 1619 by Fabriccio Bartoletti, and identied as a sugar in 1780 by Carl Wilhelm Scheele. Lactose makes up around 2~8% of milk (by weight), although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from lac, or lactis, the Latin word for milk, plus the “ose” ending used to name sugars. Lactose is the main carbohydrate in dairy products. This disaccharide is composed of glucose and galactose and is the only saccharide synthesized by mammals. Lactose plays an important role in the formation of the neural system and the growth of skin (texture), bone skeleton, and cartilage in infants. It also prevents rickets and saprodontia [1]. The need to quantify lactose came up with the knowledge of its importance in the human diet. It has been reported that cow mastitis can cause a reduction of milk yield and also of its nutritive value. Determination of the lactose content is one of the methods used to evaluate whether milk is acceptable for human consumption [2]. Moreover, the precise control of the amount of lactose in dairy food products is vital, as many people are intolerant to this carbohydrate. Therefore, the precise determination of lactose during the production process, as well as in the nal product, is fundamental for the food industry. It also has economic value since the price of milk is based on
