Protein oleogels prepared by solvent transfer method with varying protein sources
Annika Feichtinger, Dieke Groot Nibbelink, Suzanne Poppe, Lucas Bozzo, Jasper Landman, Elke Scholten
Abstract
The increasing interest in plant-based materials warrants investigating whether a method used to create protein oleogels by a solvent transfer of whey protein aggregates can be applied to other (specifically plant-based) types of globular proteins. Our results demonstrate that the solvent transfer procedure is indeed suitable to also obtain fully plant-based protein oleogels. Protein aggregates in water – the starting point for the solvent transfer – were shown to be of similar size for all protein sources (∼ 200 nm), which gave the opportunity to further investigate the effect of protein characteristics. The aggregates maintained a well-dispersed state throughout the solvent transfer procedure for whey and potato protein isolate aggregates, whereas large agglomerates (20–50 μm) were formed for egg, pea and soy protein isolate aggregates. At native protein concentration, the smaller aggregate size for whey and potato protein oleogels led to higher gel strengths (protein concentration 7 and 10%, G′ ∼ 2800 Pa) due to more efficient network formation. Next to aggregate size, the gel strength was also related to the hydrophobicity of protein aggregates, apparent from the difference in gel strength between oleogels of similarly sized whey (G′ of 2800 Pa) and potato protein aggregates (G' of 350 Pa) when diluted to the same protein concentration (7%). In an apolar environment, the higher hydrophobicity of potato protein aggregates led to weaker attractive interactions compared to the more hydrophilic whey protein aggregates. These results show that the gel strength of protein oleogels can be controlled by both protein aggregate size and protein characteristics.