Starch particles for food based Pickering emulsions

Intact starch granules are a new source of particles for stabilizing emulsions, so called Pickering emulsions. Small (1-2 μm) and uni-modal starch granules at various concentrations have been used in this study to investigate the stability of the emulsions, the drop size dependence of the starch concentration and the barrier properties of the stabilizing starch layer upon heating. The granules were modified with octenyl succinic anhydride (OSA) to increase the hydrophobicity. The drops in the emulsions prepared in this study were in the 10-100 μm range depending on the starch concentration, and the drop size decreased with an increased amount of added starch granules. During the 8 week storage, the emulsion drops were stable to coalescence and the volume occluded by the emulsion phase was unaffected or even increased. In order to increase the barrier properties at the oil-water interface the emulsions were gently heated, which induced a partial gelatinization of the starch granules. The efficiency of the barrier was characterized by a lipolysis experiment where the activity of lipase was measured. The activity of lipase was decreased with nearly 70% compared to an unheated starch stabilized emulsion, which will be useful in applications where a controlled release of specific substances in the gastro intestinal tract is desirable.