Enhancement of Istrian Malvasia wine aroma and hydroxycinnamate composition by hand and mechanical leaf removal

Leaf removal is a viticultural practice that promotes the biosynthesis of several important grape constituents by improving fruit zone microclimate. The purpose of this study was to assess the effects of hand and mechanical leaf removal, applied at the pea-size stage of berry development, on fruit zone microclimate, volatile aroma compounds, hydroxycinnamates and sensory characteristics of Istrian Malvasia (Vitis vinifera L.) wines. Three different sunlight exposure conditions were applied: hand leaf removal (HLR), mechanical leaf removal (MLR) and untreated control (UC).

Both leaf removal treatments, and especially the more intense HLR, significantly increased the concentration of varietal thiol 3-sulfanylhexan-1-ol, monoterpenes, β-damascenone and esters. The higher concentration of these aromas contributed to the improvement of wine sensory quality, as expressed by more enhanced floral, fruity and tropical sensory attributes in leaf removal treatments. Hydroxycinnamates were increased only by HLR, a treatment with a greater degree of fruit exposure to sunlight than MLR.

Leaf removal applied at the pea-size stage of berry development in a season characterized by abundant rainfall improves both the chemical composition and sensory quality of Istrian Malvasia wine, even when performed by machine, implying that this technique might be successfully applied in large-scale viticultural production. © 2018 Society of Chemical Industry.