Whey proteins-polyphenols interactions can be exploited to reduce astringency or increase solubility and stability of bioactives in foods

Abstract

Whey proteins have very interesting properties including, high solubility in water, strong interactions with polyphenols, aggregation properties and are classified as GRAS. Here the application of whey proteins to improve food formulations is evaluated. In particular, the reduction of astringency in wine by whey proteins and peptides was assessed applying an analytical method based on determination of tannins. As shown previously for beta-lactoglobulin (beta-Lg) and beta-Lg-Caseinomacropeptides fractions, here it was shown that hydrolysates interacted with polymeric polyphenols such as tannins which, led to their complexation and precipitation effectively reducing astringency. In addition, nanoparticles of beta-Lg and sweet whey were produced by applying a method developed previously in our group based on heat induced denaturation which could consistently produce nanoparticles of 200-300 nm with high colloidal stability. Here further characterisation of beta-Lg nanoparticles showed that addition of ethanol up to 28\% led to nanoparticles destabilisation mainly due to a reduction in beta-Lg overall charge. The application of centrifugal force above 863g led to the disruption of colloidal stability and beta-Lg sedimentation. However, nanoparticles were stable to freeze drying conditions. Furthermore, it was shown that sweet whey could be used instead of beta-Lg to produce nanoparticles of similar characteristics. These beta-Lg nano particles formed nanocomplexes with resveratrol which, resulted in improved solubility and increased antioxidant activity under pasteurisation conditions. The isomerization from trans to cis and a protective effect of nanoparticles against some chemical changes that result in reduced activity could explain these results. Thus, whey proteins show promise in their application for improved formulations of food/beverages with bioactive ingredients.