Milk proteins in ice cream

Abstract

Milk proteins contribute three important structural functions to ice cream. They emulsify the fat phase during homogenization to produce a stable emulsion in the mix state. Their subsequent interaction with emulsifi ers during the ageing process reduces the adsorbed protein level, thus producing a fat emulsion that is able to partially coalesce in the whipped and frozen ice cream and produce desirable fat structure. Proteins present in the serum phase of the mix during whipping contribute to the development of an air bubble interface that is capable of maintaining small and stable air bubbles. Unadsorbed proteins also increase mix viscosity, particularly in the unfrozen serum phase after cryo-concentration, which leads to enhanced body and texture and reduced rates of ice recrystallization. There are many protein ingredients available, from the traditional sources of milk solids-not-fat to the isolated and modifi ed casein-based or wheyprotein based ingredients, and it is essential for product developers to utilize the appropriate sources of proteins to deliver the functional attributes needed for their specifi c products. This chapter, therefore, outlines the structure of ice cream and the functional contributions of proteins to deliver that structure and also reviews the understanding to-date of protein modifi cations that are available to dairy and ice cream manufacturers for optimizing structure and quality.