Effects of starch granules differing in size and morphology from different botanical sources and their mixtures on the characteristics of Pickering emulsions

Abstract

The aim of this work was to investigate how mixtures of starch granules of different size and shape from different botanic sources affect starch-stabilized Pickering emulsions, and to understand which type of granules that dominate at the interface of the emulsion droplets. Pickering emulsions were prepared by combining quinoa starch with waxy maize or oat starch. The effects of the individual starches as well as the mixtures on drop size and Emulsion were investigated as a function of concentration and emulsification time. For the emulsion done with one type of starch granules the size of the starch particles influenced emulsion droplet sizes. The droplet size was also strongly influenced by starch concentration, showing a decrease in droplet size with increasing starch concentration. The emulsification time (1–5 min) influenced emulsions containing waxy maize or oat starch, but not quinoa. In the quinoa/waxy maize system, quinoa dominated at the surface of the droplets. While in the quinoa/oat system, oat is more likely to dominate the interface. Increasing the emulsification time led to a decrease in drop size in all samples, most notably for quinoa/oat emulsions for which the mean droplet size was decreased by up to 80% at the longest emulsification time (5 min). The emulsion index increased as the total starch concentration in the system was increased. In general, we could conclude that the particle size alone did not decide which starch type would dominate at the interface but that the larger the starch granules was the more the droplet size of the emulsion was affected by the emulsion time.