Residual proteins in finished wines can aggregate to form haze. To obtain insights into the mechanism of protein haze formation, a reconstitution approach was used to study the heat-induced aggregation behaviour of purified wine proteins.
A chitinase, 4 thaumatin-like protein (TLP) isoforms, phenolics, and polysaccharides were isolated from a Chardonnay wine. The same wine was stripped of these compounds and used as a base to reconstitute each of the proteins alone or in combination with the isolated phenolics and/or polysaccharides.
After a heating and cooling cycle (70°C for 1 h and 25°C for 15 h), the size and concn. of the aggregates formed were measured by scanning ion occlusion sensing (SIOS), a technique to detect and quantify nanoparticles.
The chitinase was the protein most prone to aggregate and the 1 that formed the largest particles; phenolics and polysaccharides did not have a significant impact on its aggregation behaviour.
TLP isoforms varied in susceptibility to haze formation and in interactions with polysaccharides and phenolics.
The work establishes SIOS as a useful method for studying wine haze
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