Elucidation of microscopic mechanisms of tweens on whipping capabilities of aerated emulsions: Fat crystal-membrane interaction perspective

Abstract

Aerated emulsions find wide applications in the food industry, with partial coalescence playing a crucial role as the core of such products in whipping capabilities. Although tweens are the most traditional emulsifiers used in aerated emulsions, the microscopic mechanisms of how they work are still not fully understood. This study focused on elucidating the mechanisms of Tweens in fat crystallization, oil-water interface rheology, and fat globule interface membrane properties, clarifying their roles in partial coalescence and whipping capabilities. The fat crystals induced by Tween 20 (T20) faced difficulty in puncturing the interface membrane with a high elastic modulus (5.58 mN/m), which may constrain occurrence and progression of partial coalescence. Tween 60 (T60) and Tween 40 (T40) exhibited strong interactions with proteins, with the interface film formed by T60 having a high elasticity of up to 7.79 mN/m. However, the highest elasticity interface film formed by orogenic behavior from T60 was not conducive to the interaction between fat crystals and the interfacial proteins during the whipping process. T40 not only helps to stimulate fat crystallization and create interface films with appropriate elastic strength but also plays a role in enhancing foam quality as its concentration rises. This is supported by its rheological properties and microscopic structures. The interface membrane formed by Tween 80 (T80) was viscous, leading to a significant partial coalescence but poor foam quality. This study reveals the interaction mechanisms between fat crystallization, interface membrane, partial coalescence, and the structure of aerated emulsions regulated by Tweens.