Effect of the combined use of potato protein hydrolysates and surfactants on the emulsifying and antioxidant properties in 5% fish oil-in-water emulsions

Abstract: With the increasing demand for sustainable and functional proteins/peptides from alternative sources, the application of advanced proteomics and bioinformatics tools facilitates more time- and cost-efficient research for identification of proteins/peptides with functional properties. The identification of abundant proteins and the release of highly functional peptides from plant-based sources have gained significant attention in the food industry within the last decade. Despite potatoes’ low protein content (1-2%), the global potato starch industry (3.4 Mt/year) makes them a highly relevant source of plant-based protein. Previously, we have identified abundant peptides with good emulsifying and antioxidant properties using bioinformatics and proteomics tools and validated them using in vitro model emulsions. Data-driven targeted hydrolysis enabled the release of functional peptides from the potato protein obtained from potato fruit juice, a protein-rich by-product of potato starch production.

This work focuses on the use of fractionated potato protein hydrolysates (PPH) obtained through such targeted hydrolysis using trypsin. Unfractionated and membrane-fractionated ( >10kDa, 10-5kDa, 5-0.8kDa, and < 0.8kDa) PPHs were characterized for their dual function as emulsifiers and antioxidants in 5% fish oil-in-water emulsions during 9-day storage. The combined use of PPH fractions and surfactants (Tween20 and DATEM) revealed differences between PPH fractions’ competitive adsorption to the interface. Furthermore, the combined use of PPHs and surfactants to form physically and oxidatively stable emulsions was investigated. Results showed that the smaller PPHs ( < 10kDa) provided smaller oil droplets when combined with DATEM, whereas unfractionated PPH provided the smallest droplets when combined with Tween20. PPH fractions were better antioxidants than unfractionated PPHs, where PPHs 5-10kDa and < 0.8kDa provided the best oxidative stability. Radical scavenging and metal chelating activities of PPHs indicated the best activities for the PPHs >5kDa. Overall, results show the potential in fractionation of the PPHs to uncover the dual functionality in different peptide size ranges.