Variety effect of distinct enzyme treatments during prefermentative maceration of white winegrapes on volatile organic compounds and chromatic traits

The impact of prefermentative addition of five single-enzyme activities (pectin lyase, polygalacturonase, pectin methyl esterase, xylanase, and arabinase) on the phenolic content, colour characteristics, and volatile composition of grape musts resulting from pellicular maceration of Chardonnay, Arneis, Greco, and Falanghina white varieties was studied with the aim of enhancing aroma composition without negatively affecting colour perception. In addition, standard physicochemical parameters were determined. Pectin lyase, polygalacturonase, and arabinase enzymes reduced the must browning, when compared with untreated control, as reported by lower total polyphenol index, absorbance at 420 nm, and a* colour coordinate for all varieties tested. Regarding the volatile composition determined by solid-phase extraction and GC-MS analysis, variety effect was observed for the enzyme treatments studied. The concentration of free vanillin decreased significantly in these last three varieties using polygalacturonase and arabinase treatments whereas 4-vinylguaiacol increased in pectin lyase-treated samples. Free terpene compounds, such as furan linalool oxide, increased in Chardonnay and Falanghina varieties using polygalacturonase, xylanase, and arabinase for the second variety whereas pectin lyase for the first one. Contrarily, glycosylated terpenes, such us (Z)-8-hydroxylinalool, decreased when using pectin lyase and xylanase for Arneis; however, it also occurred for Falanghina using polygalacturonase treatment. The xylanase activity influenced mostly the volatile composition of the Arneis variety whereas arabinase did for Greco and Falanghina. The differences between enzyme-treated grape musts and control samples were less evident on the Chardonnay variety. Therefore, enzyme activity can affect the volatile composition of grape must differently depending on the target variety.