The partial coalescence behavior of oil-in-water emulsions: Comparison between refrigerated and room temperature storage

Abstract

Although storage temperature is important for partial coalescence, the literature is scant on exploring the partial coalescence behavior between refrigerated and room temperature storage. In this study, comparison of the partial coalescence behavior between 4 and 20 °C was investigated towards corresponding oil-in-water emulsions, and subsequently towards the ultimate properties of the aerated colloidal system. As expected, compared to the value of Avrami constant (K) at 20 °C, the value of palm kernel stearin (PKS85) and mixtures of PKS85 and glycerol monostearate (PKS85-GMS) obtained at 4 °C increased by 22 and 14 times, respectively. PKS85 and PKS85-GMS displayed the needlelike appearance (N-type crystal) with a little layer crystal (L-type crystal) at 4 °C and spherical shape formed by L-type crystal along with granular crystal at 20 °C. Interestingly, several unstable air bubbles with irregularly-shape were observed in the aerated emulsions at 20 °C, while these emulsions at 4 °C displayed numerous rounded and uniform air bubbles with glossy surface. This was attributed to the sufficient stiff needle crystals at 4 °C, facilitating the coalescence of fat globules via liquid fat bridges, further forming a rigid crystal-based network and trapping the air bubbles. Therefore, our findings gained an insight into the partial coalescence behavior in emulsion, providing theoretical support for designing and optimizing the production process of foam structure products.

Keywords: Fat crystal behavior; Oil-in-water emulsion; Partial coalescence; Temperature.