Functionality of bovine milk proteins and other factors in foaming properties of milk: a review

Abstract

For many dairy products such as cappuccino-style beverages, the top foam layer determines the overall product quality (e.g. their appearance, texture, mouthfeel and coffee aroma release rate) and the consumer acceptance. Proteins in milk are excellent foaming agents, but the foaming properties of milk are greatly affected by several factors such as the protein content, ratio of caseins to whey proteins, casein micelle size, pH, minerals, proteolysis, presence of low molecular weight compounds (lipids and their hydrolyzed products) and high molecular weight compounds (polysaccharides); milk processing conditions (e.g. homogenization, heat treatment and aging); and foaming method and temperature. These factors either induce changes in the molecular structure, charge and surface activity of the milk proteins; or interfere and/or compete with milk proteins in the formation of highly viscoelastic film to stabilize the foam. Some factors affect the foamability while others determine the foam stability. In this review, functionality of milk proteins in the production and stabilization of liquid foam, under effects of these factors is comprehensively discussed. This will help to control the foaming process of milk on demand for a particular application, which still is difficult and challenging for researchers and the dairy industry.

Keywords:

• Foamability
• foam stability
• protein functionality
• casein
• whey protein

Acknowledgements

The ARC Dairy Innovation Hub is a collaboration between The University of Melbourne, The University of Queensland and Dairy Innovation Australia Ltd. The authors acknowledge the facilities, and the scientific and technical assistance, of the School of Agriculture and Food Sciences at The University of Queensland.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded through Australian Research Council's Industrial Transformation Research Hub (ARC-ITRH) grant with an industry partner.