Effect of homogenisation in foam and emulsion mix beverage colloidal system: A case in Teh Tarik

Abstract

Teh Tarik is a frothed milk tea consisting of Ceylon Tea, condensed milk, sugar, where it is traditionally prepared by pulling motion to get aerated. High-shear homogenisation through rotor-stator homogeniser was explored in this study as an alternative method to produce Teh Tarik at a larger scale and at the same time enhancing the stability of the Teh Tarik emulsion and foam. Varying speeds (11,000 rpm, 18,000 rpm and 25,000 rpm) of homogenisation resulted in size reduction of milk fat globules to various degrees. This reduction in particle size by at least 0.4 μm consequently increased the stability of the milk tea emulsion, which is the most significant (α = 0.05) at the speed of 18,000 rpm. At the same time, increasing speed of homogenisation from 11,000 rpm to 18,000 rpm and 25,000 rpm also reduces dynamic surface tension through the increased protein adsorption rate at the water-air interphase and ultimately reducing foam drainage. Subsequently, the improved physical stability of emulsion and foam could be made use to develop satiety- and satiation-enhanced beverage as a modus operandi to reduce calorie intake among Malaysians.