Effect of Steam Frothing on Milk Microfoam: Chemical Composition, Texture, Stability and Organoleptic Properties

Abstract

This study focuses on the evaluation of microfoam produced from processed milk using the steamer of the espresso machine. Milk foam, defined as microfoam by the Specialty Coffee Association, should meet strict requirements and cannot be accepted in the evaluation if it does not. The results confirm that industrial thermal processing of milk affects the structure of milk proteins and thus the ability to form stable foam when milk is foamed in espresso machines. Frothing milk with steam alters the properties of the foam, particularly microfoam, including the rate of foam subsidence, viscosity, and bubble size distribution. It was shown that the optimal final temperature of steam frothing is in the range of 50 °C to 60 °C. The results of sensory tests show that consumers differentiate between the aroma and flavour of pasteurised and UHT milk, describing the degree of this difference as from moderate to strong.

Keywords: Milk, Foam, Microfoam, Stability, Heat treatment, Foaming temperature