Effect of different pre-fermentation treatments on polyphenols, color, and volatile compounds of three wine varieties.

Wines produced by three different grape varieties were treated with seven pre-fermentation techniques to analyze their variation in polyphenolic compounds, color parameters, and aromatic components. For polyphenolic compounds and color parameters, a better result was obtained after the grape pulp treatment, with the maximum impact observed after joint treatment with thermovinification and pectolytic enzymes, followed by thermovinification and cold soak, while pectolytic enzymes treatment alone was ineffective, resulting in almost no effect. On the contrary, the application of thermovinification and cold soak treatments before crushing the whole juice led to a dramatic decline in most indexes. For aromatic components, the joint treatment of thermovinification and pectolytic enzymes on grape pulp significantly affected its amount and type, in addition to giving the wine a mellow aroma.