Influence of Milk Fat on Foam Formation, Foam Stability and Functionality of Aerated Dairy Products

Abstract

In dairy industry, foaming of milk can be undesirable in many processes (e.g. bottle filling, milk transportation in the pipe systems or reconstitution of milk powders) or desirable for many products (e.g. cappuccino-style drinks, milkshake, ice cream or whipped cream). For foam-based products, the quality of foam imparts the body, smoothness and lightness to the products, and constitutes to the main sensory appeal to the consumers. Depending on the continuous phase in which air bubbles are dispersed, the foam-based products can be categorized into liquid or solid foams in which the continuous phase exists as liquid phase or transforms to (semi-) solid phase, respectively. The formation and stability of milk foam are determined by many factors including properties of milk (origin, age, composition, protein/solid concentration, presence of surfactants, fat content, etc.), processing conditions (foaming method, heating treatment, homogenization, or temperature and/or pH at which foam is created), even seasonality or added substances. Among these factors, milk fat has both detrimental and beneficial effects on the development of foam and its stability depending on its physical state and type of foam (liquid or solid foam). In this chapter, together with description of importance of foam or foaming in the manufacture of aerated dairy products and mechanism of the foaming process, a particular emphasis is placed on the impact of the milk fat on the foaming behavior of both liquid and solid foams, aiming to provide an insight on the foaming process, by which the foaming of milk can be controlled on demand for a particular application. Effects of the other factors on the foaming process are not in the scope of this chapter.