Hanseniaspora in wine-making: their genetic modification and potential role in acid modulation

Making high quality but affordable Pinot noir (PN) wine is challenging in most terroirs and New Zealand’s (NZ) situation is no exception. To increase the probability of making highly typical PN wines producers choose to grow grapes in cool climates on lower fertility soils while adopting labour intensive practices. Stringent yield targets and higher input costs necessarily mean that PN wine cost is high, and profitability lower, in line-priced varietal wine ranges. To understand the reasons why higher yielding vines are perceived to produce wines of lower quality we have undertaken an extensive study of PN in NZ. Since 2018, we established a network of twelve trial sites in three NZ regions to find individual vines that produced acceptable commercial yields (above 2.5kg per vine) and wines of composition comparable to “Icon” labels. Approximately 20% of 660 grape lots (N = 135) were selected from within a narrow juice Total Soluble Solids (TSS) range and made into single vine wines under controlled conditions. Principal Component Analysis of the vine, berry, juice and wine parameters from three vintages found grape berry mass to be most effective clustering variable. As berry mass category decreased there was a systematic increase in the probability of higher berry red colour and total phenolics with a parallel increase in wine phenolics, changed aroma fraction and decreased juice amino acids. The influence of berry size on wine composition would appear stronger than the individual effects of vintage, region, vineyard or vine yield. Our observations support the hypothesis that it is possible to produce PN wines that fall within an “Icon” benchmark composition range at yields above 2.5kg per vine provided that the Leaf Area:Fruit Weight ratio is above 12cm2 per g, mean berry mass is below 1.2g and juice TSS is above 22°Brix.

Dans la region Nord-Est du Brésil, située à la Vallée du São Francisco, localiséee entre les paralleles 8-9º HS, la production de vins tropicaux a commencé il y a une vigntaine d’années. Dans cette région, il est possible d’avoir au minimum deux récoltes par an, car la moyenne de température est de 26 ºC, avec une pluviosité moyenne de 550 mm entre les mois de janvier-avril.

Recently, the European Commission seems to have inaugurated a new mechanism for regulating the wine sector. Through two communications, articulated in the form of “Questions & Answers”, concerning the new rules for labeling (24.11.2023) and dealcoholization of wine (15.01.2024), the Commission is not simply “explaining” the new rules but, in an approach close to the theory of “Circulaire Normative” established in comparative law, chooses among different interpretations and even adds Praeter Legem constraints.

In this last ten years period, there has been many integrated and interdisciplinary studies to determine the aptitude of different zones to viticulture (Lulli et al., 1989 ; Costantini, 1992 ; Fregoni et al., 1992). The researches needed some différent knowledges about environment characteristics (soil, climate), ecology, vineyard management, vine genetic, winemaking and sensory analysis. The interaction of all these knowledge produced the assessment about the environmental vocation (Scienza et al., 1992). By means of this metodology, the “viticultural vocation” joined the word “zoning”, that is the territory parting for its ecopedological and geographical characteristics in relation to adaptative answer of winegrape (Morlat, 1989).

Grape stalks are a byproduct of the winemaking process and represent a valuable and inexpensive source of bioactive compounds. While their direct use in whole bunch fermentation is known, the majority of grape stalks are discarded, posing environmental and economic challenges.