Protein content of amaranth and quinoa starch plays a key role in their ability as Pickering emulsifiers

Abstract Growing concerns about the safety of using synthetic surfactants to stabilize food emulsions have inspired a trend towards the use of natural ingredients like starch as alternative food stabilizers in what are called Pickering emulsions. The hydrophilicity of commercially available starches, however, necessitates further chemical treatment to increase their hydrophobicity and emulsifying ability. Here we demonstrate an alkaline isolation method to extract amaranth and quinoa starch from flour while retaining a high protein content, which gives these materials an emulsifying ability comparable to octenyl succinylated starches. We highlight the key role played by protein by showing that a serial reduction of the protein content leads to a parallel reduction in emulsifying ability, and that pH affects this ability. Our method of retaining proteins naturally present in amaranth and quinoa not only bolsters the nutritional profile of the food but also takes advantage of the proteins’ native hydrophobicity for improved emulsification.