Whey chemical composition

Table 2.8. Chemical Composition of Selected Commercial Whey-Based Food Ingredients.

The whey powder (from bovine milk) used in this experiment was purchased from Sigma Chemical Co. (St. Louis, MO, USA). The chemical composition of whey protein is shown in Table 1. Samples were prepared by diluting the appropriate amount of whey powder with water. The concentration of the samples remained at approximately 200,000 ppm. The standard chemicals of a-lactalbumin (Type III deplete, form bovine milk, approximately 85%), p-lactoglobulin (form bovine milk, approximately 90%), and BSA were purchased from Sigma Chemical Co. Standard protein solutions were prepared in water. Standard solutions were made for each protein of 10 mg dissolved in 1 L with water. The water was filtered with HA 0.5-pm membranes (Division... 

Milk contains 3.3% total protein. There are two major categories of milk protein that are broadly defined by their chemical composition and physical properties. The casein family contains phosphorus and will coagulate or precipitate at pH 4.6. The serum [whey] proteins do not contain phosphorus, and these proteins remain in solution in milk at pH 4.6. The principle of coagulation, or curd formation, at reduced pH is the basis for cheese curd formation. In cow s milk, approximately 82% of milk protein is casein and the remaining 18% is serum, or whey protein. 

Magalhaes, K. T., Dias, D. R., de Melo Pereira, G. V., Oliveira, J. M., Domingues, L., Teixeira, J. A, . . . Schwan, R. F. (2011). Chemical composition and sensory analysis of eheese whey-based beverages using kefir grains as starter culture. International Journal of Food Science Technology, 46(4), 871-878. 

Raw milk is a unique agricultural commodity. It contains emulsified globular lipids and colloidally dispersed proteins that may be easily modified, concentrated, or separated in relatively pure form from lactose and various salts that are in true solution. With these physical-chemical properties, an array of milk products and dairy-derived functional food ingredients has been developed and manufactured. Some, like cheese, butter, and certain fermented dairy foods, were developed in antiquity. Other dairy foods, like nonfat dry milk, ice cream, casein, and whey derivatives, are relatively recent products of science and technology. This chapter describes and explains the composition of traditional milk products, as well as that of some of the more recently developed or modified milk products designed to be competitive in the modern food industry. 

The whey produced during cheese and casein manufacturing contains approximately 20% of all milk proteins. It represents a rich and varied mixture of secreted proteins with wide-ranging chemical, physical and functional properties (Smithers et al., 1996). Due to their beneficial functional properties, whey proteins are used as ingredients in many industrial food products (Cheftel and Lorient, 1982). According to Kinsella and Whitehead (1989), functional properties of foods can be explained by the relation of the intrinsic properties of the proteins (amino acid composition and disposition, flexibility, net charge, molecular size, conformation, hydrophobicity, etc.), and various extrinsic factors (method of preparation and storage, temperature, pH, modification process, etc.). 

Although whey protein concentrates possess excellent nutritional and organoleptic properties, they often exhibit only partial solubility and do not function as well as the caseinates for stabilizing aqueous foams and emulsions (19). A number of compositional and processing factors are involved which alter the ability of whey protein concentrates to function in such food formulations. These include pH, redox potential, Ca concentration, heat denaturation, enzymatic modification, residual polyphosphate or other polyvalent ion precipitating agents, residual milk lipids/phospholipids and chemical emulsifiers (22). 

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