In the food industry, new product development often aims to expand the range of sensory characteristics. This is especially important in confectionery, where delivery of indulgent flavour and texture is the key. Emulsion technology is widely used in food production for its ability to create unique microstructures. These microstructures contribute to the distinctive texture and mouthfeel of products such as margarine, mayonnaise, and dairy cream. For confectionery, the potential of emulsion technology remains largely untapped. To adopt this technology in confectionery products, several challenges require attention. The complex rheology arising from the high concentration and type of sugar, their impact on the performance of emulsifiers and how they both influence emulsion formation and stability. While previous studies have explored the impact of sugar on emulsifier performance and emulsion formation^[1], they have been limited to a narrow range of emulsifiers. Additionally, the sugar concentrations used were not high enough to reflect those typically found in confectionery products.

In this study, the effect of high concentration and type of sugar (sucrose, fructose, and glucose) on emulsion formation, stability and rheological behaviour was evaluated. To assess how sugar influences different emulsifiers’ performance, emulsions were prepared with three emulsifiers—Tween 20, whey protein isolate (WPI), and pea protein isolate (PPI)—under varying sugar conditions. Interfacial tension (IFT) and structural changes of emulsifiers were analysed to evaluate their interfacial properties at varrying sugar conditions. To further characterise the resulting emulsions, emulsion droplet size distribution, stability and rheology were assessed. It is shown that while different sugar types had little effect on IFT, different sugar concentrations led to distinct IFT values with the presence of emulsifier at the same concentration. This can be explained by the impact of sugar on emulsifier strucural changes and performance^[2]. Higher sugar concentrations resulted in smaller mean droplet size and a more monodisperse distribution. This outcome may be attributed to two factors, the significantly different continuous phase viscosity and the changes of IFT under varrying sugar conditions^[3,4]. Despite the difference in droplet size and distribution, the rheological behaviour of emulsions prepared under varying sugar conditions remained consistant. The above factors also further influence emulsion stability. While all the emulsions maintained stable against droplet size changes, higher sugar concentrations demonstrated improved resistance against creaming, except the PPI emulsions at high sugar concentration, which exhibited flocculation and behaved differently from the other samples. In conclusion, sugar concentration and its type impact emulsion formation and stabilty by influencing continuous phase rheology and emulsfier performance. Higher sugar concentrations result in smaller droplet sizes, monodisperse distributions and improved stability.

1. Lee JC, Timasheff SN. The stabilization of proteins by sucrose. Journal of Biological Chemistry. 1981 Jul 25;256(14):7193–201.
2. Edelman R, Kusner I, Kisiliak R, Srebnik S, Livney YD. Sugar stereochemistry effects on water structure and on protein stability: The templating concept. Food Hydrocolloids.
3. Hoorfar M, Kurz MA, Policova Z, Hair ML, Neumann AW. Do polysaccharides such as dextran and their monomers really increase the surface tension of water? Langmuir : the ACS journal of surfaces and colloids.
4. Docoslis A, Giese RF, van Oss CJ. Influence of the water–air interface on the apparent surface tension of aqueous solutions of hydrophilic solutes. Colloids and Surfaces B: Biointerfaces. 2000 Dec 15;19(2):147–62.