Pectolytic enzyme treatment partially degrades an arabinogalactan protein-rhamnogalacturonan I-xyloglucan co-polymer in red wine as characterised using epitope mass profiling

Polysaccharides are important metabolites in red wine but are challenging to separate from yeast-derived mannoproteins, and costly to identify using sialylation and gas chromatography. Affinity and gel permeation chromatography was combined with immunodetection of various specific plant cell wall polysaccharide epitopes to understand this complex mixture of extracted cell wall polymers. A survey of Cabernet Sauvignon wines produced with and without pectolytic enzymes suggested that enzyme-treated wines have fewer polysaccharides in the 85-105 kDa and 1050-6000 kDa ranges. When yeast-derived mannoproteins are excluded (15.3% of total), pectolytic enzyme treatment was shown to alter the molecular weight wine polysaccharide composition between the 100-1000 kDa ranges. Furthermore, ELISA data suggested that many of the soluble polysaccharides in the 300-1000 kDa range are an arabinogalactan protein-rhamnogalacturonan I-xyloglucan co-polymer. This is the first report to use ELISA to identify changes in specific polysaccharide classes during enzyme preparation used in wine maceration.

Automated summary

Polysaccharides in red wine, particularly those derived from yeast, are difficult to separate and identify. This study used chromatography and immunodetection to analyze the composition of extracted polysaccharides, revealing changes in molecular weight and specific classes of polysaccharides in enzyme-treated wines. ELISA data suggested the presence of a specific arabinogalactan protein-rhamnogalacturonan I-xyloglucan co-polymer in the soluble polysaccharides of these wines. This is the first report to use ELISA to identify changes in specific polysaccharide classes during enzyme preparation in wine maceration.