Content area
Full Text
ABSTRACT
Casein, the main milk protein that constitutes approximately 75% of that protein, is in the form of micelles with a radius of 0.1 μm. Most of the methods used for the preparation of casein from milk basically involve a removal of the fat of the milk followed by a destabilisation process of the desired protein by insolubilization. This process is achieved either by an isoelectric precipitation, i.e. by acidification in order to reach the isoelectric point of the casein, or an enzymatic destabilisation of the casein micelle by the addition of the rennin enzyme, which could be of animal, plant or microbial origin.
This review illustrates the functional and physico-chemical properties of the different types of casein and their use in food and non-food industrial applications. These types of protein include mainly rennet casein, acid casein, caseinate, phosphocasein, enriched casein fractions, casein fragments and casein-whey protein aggregates. The most commonly used casein in food and non-food applications is the acid- and rennet casein. The food applications of casein include mainly its use as an ingredient for the purpose of modifying the functional or physicochemical properties and/or improving nutritional value of the food stuff, e.g. meat products, cheese, baked products.. etc. The current publication focuses on recent research work done on the use of casein, as a principal source of protein, and its major impact on the functional properties of process imitation cheese. The non-food applications of casein include its use in the adhesive agents', paper, textile and plastic industry.
1. INTRODUCTION
The word milk comes from the old Germanic word meluk, which means the liquid secreted by the mammary glands of female mammals for suckling their young. Milk is considered as the real commodity in the food industry, because of milk proteins, which are the core of many industrial processes, due to their unique properties (De Kruif, 2003). The approximate composition of milk is in average as follows, 4.36% fat, 4.51% lactose and 3.87% protein. The total dry matter content is 13.2%. In general, milk can be viewed as a colloidal dispersion of protein and fat particles in a continuous phase (solvent) or watery solution of salts and lactose. Milk proteins constitute about 3.87% of milk. These proteins consist of casein, the main...