Grape cluster microclimate influences the aroma composition of Sauvignon blanc wine. (1st November 2016) - Martin, Damian
Highlights: Wine volatile thiol concentrations were not affected by cluster microclimate nor berry ripening. Wine from shaded clusters had nearly double the methoxypyrazine concentrations of exposed clusters. Natural cluster exposure reduced methoxypyrazines without altering juice sugar/acid balance. Natural cluster exposure effects on wine composition were different to effects of leaf removal. Abstract: New Zealand Sauvignon blanc (SB) wines are characterised by a distinctive combination of tropical-fruity and green-herbaceous aromatic compounds. The influence of sunlight exposure of grape clusters on juice and wine composition was investigated, with the aim of manipulating aromatic compounds in SB wine. In the absence of basal leaf removal SB clusters naturally exposed to sunlight were riper than shaded clusters, evidenced by higher total soluble solids (TSS) and proline, and lower malic acid, 3-isobutyl-2-methoxypyrazine (IBMP) and arginine. Volatile thiols in wines did not differ between shaded and exposed clusters. At equivalent TSS, cluster exposure had little or no effect on malic acid concentration. Conversely, wine from shaded clusters had almost double the IBMP concentration of wine from exposed clusters at equivalent TSS. The effects on SB juice and wine composition of natural variations in cluster microclimate are not comparable with the effects of cluster exposure created through leaf removal.