Effect of Water Addition on Physical Properties of Emulsion Gels

Abstract

The aim of this work was to evaluate how the physical properties of oleogels formulated with candelilla wax (CLX), monoglycerides (MG), and hardfat (HF) change with the addition of 1–30% water (w/w). Physical properties such as crystal microstructure, melting and rheological behavior, hardness, oil binding capacity, and thermal stability were evaluated. The oleogels evaluated in this study formed stable water-in-oil emulsion gels at 25 °C without the use of additional emulsifiers. The water addition in a range from 1 to 20% (w/w) resulted in a reduction in crystal size (Dm) from approximately 10 μm for the oleogel to less than 8 μm for the emulsion gels. This reduction in crystal size suggests that a well-organized crystalline network was formed in the emulsion gels resulting in improved physical properties. Emulsion gels with 1 to 20% (w/w) water showed a narrower melting profile, higher firmness, and lower oil loss compared to those of oleogel, and showed higher stability after temperature cycling at 40 °C. Samples with 1 and 5% w/w of water showed the best improvement in physical properties since they were 3 times harder than the respective oleogel with values of 0.42 N for the emulsions and 0.15 N for the oleogel. Also, the water addition increased G’ value from 4132.92 Pa for oleogel to 13157.78 Pa for emulsion with 1% water and 9702.35 Pa for emulsion with 5% water. The obtained results suggest that water amount up to 20% (w/w) can be added to oleogel to form stable emulsion gels.