Microstructure of Cheese Products

Cheese is a complex soft matter that is composed of a protein matrix in which fat, water, minerals and bacterial colonies and their metabolites are entrapped. The arrangement of these components on a micro scale is known as the microstructure of cheese. The microstructure of cheese has a major influence on its textural and functional properties. The microstructure evolves throughout the cheese processing steps. In this chapter, various factors like addition of calcium chloride, rennet/acid coagulations, coagulation temperature, syneresis, salting, ripening, homogenization, high pressure treatments and others that affect the microstructure of cheeses are discussed in detail. The microstructures of various components like protein, fat and calcium, in the cheese matrix are covered. The protein microstructure in cheese mainly develops from casein micelles. The fat globules disrupt the structure by binding the casein matrix. The various organizations of lipids in cheese matrix are covered. Calcium is considered as one of the major compositional variables that affect the microstructure of cheese. The bacterial colonies which are randomly distributed and static within the cheese matrix are highlighted. Every cheese variety has different characteristic structural features and microstructures of selected varieties of cheeses are also described. The microstructures of cheeses are studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and light microscopy. Although these are considered as older techniques, these are still used to study microstructure of various cheese products. The confocal laser scanning microscopy (CLSM) is nowadays widely used. The CLSM technique helps in three-dimensional visualization of components as well as showing live and dead bacteria of the various cheese products. The uses of CLSM in studying the microstructure of cheeses are covered in the present chapter. The complex matrix of cheese affects the entire digestion process, and this is also briefly highlighted in this chapter.