Vintage

Abstract: Wine grapes present a unique biogeography model, wherein microbial biodiversity patterns across viticultural zones not only answer questions of dispersal and community maintenance, they are also an inherent component of the quality, consumer acceptance, and economic appreciation of a culturally important food product. On their journey from the vineyard to the wine bottle, grapes are transformed to wine through microbial activity, with indisputable consequences for wine quality parameters. Wine grapes harbor a wide range of microbes originating from the surrounding environment, many of which are recognized for their role in grapevine health and wine quality. However, determinants of regional wine characteristics have not been identified, but are frequently assumed to stem from viticultural or geological factors alone. This study used a high-throughput, short-amplicon sequencing approach to demonstrate that regional, site-specific, and grape-variety factors shape the fungal and bacterial consortia inhabiting wine-grape surfaces. Furthermore, these microbial assemblages are correlated to specific climatic features, suggesting a link between vineyard environmental conditions and microbial inhabitation patterns. Taken together, these factors shape the unique microbial inputs to regional wine fermentations, posing the existence of nonrandom “microbial terroir” as a determining factor in regional variation among wine grapes.

Abstract: A long-term (1952-1997) climatology was developed using reference vineyard observations in Bordeaux, France. The procedure partitioned the season into growth intervals from one phenological event to the next (budburst, floraison, veraison, and harvest) in which climatic influences were summed and assessed. The data were then used to investigate the relationships between climate and phenology, berry composition at harvest, total production, and quality. Over the last two decades, the phenology of grapevines in Bordeaux has tended towards earlier phenological events, a shortening of phenological intervals, and a lengthening of the growing season. Merlot and Cabernet Sauvignon varieties have tended to produce higher sugar to total acid ratios, greater berry weights, and greater potential wine quality. Vintage ratings have shown a general increase over the last two decades paralleling the observed phenology and composition trends. The composition and quality trends were mostly described by increases in the number of warm days during floraison and veraison and a reduction in precipitation during maturation. Production variability was not as readily described by phenological-interval climate parameters, but regression modeling did indicate that rainfall during physiologically important periods (flowering and maturation) tended to decrease crop production. By variety, the relationships between phenology, climate, and composition were typically higher (both positive and negative) for Merlot than for Cabernet Sauvignon and could be an indication that, in Bordeaux, Merlot is more phenologically and climatologically sensitive. Additionally, sugar to acid ratios revealed that both Merlot and Cabernet Sauvignon composition influenced Bordeaux wine quality, although variations in Cabernet Sauvignon described substantially more of the variability in ratings. This indicates that the wine industry in Bordeaux is more dependent Cabernet Sauvignon for good vintages than on Merlot.

Abstract: Red wine colour is an integration of contributions from monomeric anthocyanins and polymeric pigment forms. Because of gross differences between the two fractions in their responses to pH change and to SO2 addition, approximate measures of the states of anthocyanin equilibria in young red wines can be routinely made. Recent correlations of such measures with independent assessments of relative wine quality have prompted further examination and development of the original analytical concepts. The equilibria may be described in terms of two percentage parameters α and α ', the values of which are related to wine pH and to SO2 added after fermentation. Measures of free SO2 and also molecular SO2, anthocyanin content and total phenolics are obtained from the same set of spectral data. The interpretations are based upon a number of analytical premises for which certain approximations have been necessary. These appear to be well justified in comparative evaluations because of the wide range of parameter values observed in surveys of current vintage wines. Observations of ageing changes in the composition of wine colour, with proposed spectral indices of “chemical age”, are also presented.

Abstract: A hedonic price function, relating the price of Australian wine to its attributes, is estimated. Six attribute groups are found to be statistically important in explaining deviations from average wine prices, i.e., quality, cellaring potential, grape variety/style, grape region, grape vintage and producer size. Various interaction terms between these variables and the impact of the year of marketing are also modelled. The consequent marketing implications for producers and consumers are discussed.