Evaluation of the potential astringency of the skins and seeds of different grape varieties based on polyphenol/protein binding

The potential astringency of eight grape cultivars was evaluated based on polyphenol/protein binding. The parameters such as weights, sizes, total phenols, flavanols and tannins of different grape tissues were determined, and the polyphenol/protein binding was analyzed by SDS-PAGE and spectroscopy. The Cabernet Sauvignon had the highest skin proportion, while the Blue French had the highest seed proportion. The Blue French seeds had the highest total phenolic content, while the Cabernet Sauvignon skins had the highest total phenolic content. SDS-PAGE showed that the seed extracts had a better affinity than skin extracts for saliva proteins, but fluorescence spectra demonstrated that the interactions of skin polyphenols with protein were more complex. These results may provide some useful information on grape potential astringency's evaluation and wine-making in China.