Milk Emulsions: Structure and Stability

Abstract

The main aim of this research is to investigate the characteristics of milk and milk proteins as natural emulsifiers. It is still largely unclear how the two main fractions of the milk proteins behave as emulsifier in highly concentrated emulsions. The surface-active effect of these is determined experimentally for emulsions with a high oil content (φ > 0.7), in this case fully refined rapeseed oil. Recent publications have not yet sufficiently investigated how proteins from native milk behave in emulsions in which a jamming transition is observed. In addition, scientific measurements comparing fresh milk emulsions and emulsions of dried milk protein powders based on rheological and thermal properties are pending and unexamined. The emulsions, prepared with a rotor-stator disperser, are investigated by their particle size and analysed by microscopy, characterised by their rheological properties. The behaviour under shear is directly observed by rheo-optical methods, which enables the direct observation of the dynamic behaviour of the oil droplets undergoing a size selective jamming transition. For a better understanding of the contributions of the different emulsifying proteins, oil-in-water emulsions have been prepared by using whey protein isolates and sodium casinates. Their different role (and function) on the interface activity can be assigned to the droplet sizes and mechanical behaviour during increasing shear deformation. In addition, solid (gelled) emulsions are prepared by heating. It is shown that the cysteine-containing whey proteins are mainly responsible for the sol–gel transition in the continuous water phase and the formation of soft solids.

Evaluation of the physico-chemical properties of potato starch-based foods and their interactions with milk protein and soybean oil

“…In addition, SBO droplets in CA-SBO presented a somewhat smaller average size and a narrower span than those in WP-SBO. All of these were in agreement with the established common knowledge that CA demonstrates a stronger emulsifying capacity than WP ( Braun, Hanewald, & Vilgis, 2019 ). Apparently, as did in the pure CA system, CA micelles were observed in the CA-SBO system.…”

Evaluation of Microbial Numbers and Physical Properties of Milk Preserved with Different Time of Pre-Heating and Pulsed Electric Fields (PEF) Exposure

“…Milk and milk proteins (caseins by around 80% and whey proteins by approximately 20%) are widely used as a natural emulsifier with high oil content. A stabilization of the fat phase in milk can be achieved via different mechanisms of emulsification (Braun et al, 2019). In this research, it can be clearly observed that the pre-heating combined with PEF exposure in raw milk results in significant decrease (p < 0.05) of emulsion stability of raw milk (Table 3).…”

“…Regarding the emulsion stability, it was affected by the presence of oil phase. The increasing concentration of oil phase in the milk would results in the unstable emulsions (Braun et al, 2019). Moreover, the measurement of viscosity in milk would give an impact on rheological properties of milk, while the lightness would cause an enzymatic change affecting the milk color, which eventually affect the consumers' preference.…”

Optimasi Waktu ¬pre-Heating Dan Waktu Pulsed Electric Field Terhadap Total Mikroba Dan Sifat Fisik Susu

“…Namun, stabilitas emulsi susu segar maupun susu pasteurisasi non homogenisasi relatif tidak stabil sehingga mengakibatkan terjadinya pemisahan fraksi lemak dan protein pada susu. Beberapa cara yang dapat dilakukan untuk meningkatkan stabilitas emulsi pada susu pasteurisasi yaitu melalui proses homogenisasi maupun penambahan emulsifier (Braun, et al, 2019;Wang, et al, 2016).…”