THOM HUPPERTZ¹*, MARY A. SMIDDY², ALAN L. KELLY², H. DOUGLAS GOFF³
*Corresponding author
1. NIZO food research P.O. Box 20 Ede, 6710BA, The Netherlands
2. University College Cork Department of Food and Nutritional Sciences Cork, Ireland
3. University of Guelph Department of Food Science Guelph, Canada

Abstract

Milk proteins play a crucial role in many food products, including ice cream. In this aerated frozen emulsion, milk proteins are crucial in the emulsification of the fat, the stabilization of air bubbles and the structuring of the continuous phase throughout which air bubbles and ice crystals are dispersed. When ice cream mixes are subjected to treatment by high pressure processing (HPP) prior to freezing, the casein micelles in milk are disrupted. As a result, the viscosity of the ice cream mix is increased strongly and ice cream free of stabilizer can be produced, without compromising on the stability and mouth feel of the product. Structuring of milk proteins in ice cream by HPP or other means thus offers opportunities for the replacement of fat and stabilizers in ice cream without compromising on hedonic quality parameters.

INTRODUCTION
Due to their abundance, ease of isolation and crucial role in human nutrition, milk proteins are the best characterized and most widely used food proteins. Milk proteins distinguish themselves from most other food proteins in that they naturally exist in an aqueous environment and are thus readily soluble. This solubility is combined with a high nutritional value, bland flavour profile and wide array of desirable functional properties, such as emulsification, foaming, gelation and heat stability. Two classes of milk proteins exist, i.e., the caseins and the whey proteins, which represent ~75 percent and 25 percent of protein in bovine milk, respectively. The whey proteins are a diverse class of globular, heat-labile proteins, of which α-lactalbumin, β-lactoglobulin, serum albumin and the immunoglobulins are the most abundant, whereas the caseins are a class of 4 rather unique phosphoproteins that exist in milk in the form of sterically-stabilized association colloids called casein micelles. These casein micelles are highly hydrated, containing ~75 percent water, and consist of ~10000 casein molecules, as well as small quantities of calcium ...