Polysaccharide Functionality in Wine-like Model Systems with Oat and Egg White Model Proteins

Abstract

Interactions between wine proteins and polysaccharides have the capacity to regulate the stability, shelf-life, and turbidity of red wines. Understanding these macromolecular interactions helps with maintaining stability and reproducing high quality wines. Model polysaccharides (carboxymethyl cellulose, mannoproteins, and fruit pectin) and model proteins (egg white and oat protein) were selected to assess protein–polysaccharide interactions within a model wine solution. The wine-like solution was created to simulate the correct pH, ethanol strength, and pigment content. Any interactions with polymeric pigments—anthocyanins and tannins—can also be investigated in this matrix. To analyze the aggregative potential of the macromolecules, particle size and Zeta-potential (ζ-potential) measurements were recorded for the samples with increasingly complex compositions. Carboxymethyl cellulose was found to increase particle sizes, likely binding more than proteins, but also improved the overall stability of the solution. Fruit pectin and mannoprotein were effective at causing precipitation while not removing the color of the model wine. The use of mannoprotein ensued in overall smaller particles for both suspended aggregate and precipitate sizes, indicating higher selectivity. Fruit pectin increased precipitate sizes and decreased suspended aggregate sizes. This study implements model proteins to evaluate complex macromolecular interactions using measurements of ζ-potential and particle size.