The use of viticultural and oenological performance of grapevines to identify terroirs: the example of Sauvignon blanc in Stellenbosch

Oxygen transfer rate (OTR) is a technical property of closure, and it modulates the oxygen supply to the wine during its bottle aging. It’s an important parameter to take into account in the analysis of wine aroma evolution. OTR distribution is well documented for new closures, but little research has been published on its determination for aged closures. Initial oxygen release after bottling impacts the composition of wines during the first years of storage), but the link between OTR, sensory perception and aroma composition after many years of aging has not yet been clearly studied. 

Del Barrio-Galán, R.a, b, Gómez-Parrini, A.a, Peña-Neira, A.b a Lallemand Inc. Chile y Compañía Limitada, Rosario Norte 407, piso 6, Las condes, Santiago, Chile b Department of Agro-Industry and Enology, Faculty of Agronomical Sciences, University of Chile, Post Office Box 1004, Santa Rosa 11315, La Pintana, Santiago, Chile It is well known that polysaccharides, mainly mannoproteins, play an important role on physical, chemical and sensory quality of wines. The ageing of white wines on lees is used in order to release higher amounts of polysaccharides by the autolytic processes in order to obtain higher-quality wines. However, this technique is too slow, because the temperature and pH conditions are not the most suitable for this process. In addition, it can also involve certain disadvantages such as a greater demand on winery resources, a longer period of wine storage, the appearance of reduction notes and some microbiological alterations.

Climate change presents a significant challenge to grape growing worldwide as increased temperatures lead to wines with increased sugar and pH levels. Manipulation of the exposed leaf area is a powerful lever governing the assimilation and storage of non-structural carbohydrates in grapevines. Reducing the leaf-to-fruit ratio is now considered as a tool for adapting to hotter and dryer grape growing conditions.

Many volatile compounds of different chemical/biochemical origin contribute to wine aroma. Certain key ‘varietal’ aroma compounds such as methoxypyrazines are formed in the grape and appear to be only scarcely influenced by fermentation.

Bud death due to cold damage is a recurrent and major economic issue with Vitis vinifera L. in the Northeastern U.S. winegrowing regions. Primary buds – and sometimes secondary and tertiary buds – are often damaged by fluctuating temperatures in the winter and early spring. To maintain balanced vegetative and reproductive growth of a vine, pruning practices need to be adjusted to account for bud damage. Conventional bud damage assessment requires growers to sample canes/spurs, cut nodes with a razor blade, and then visually assess bud damage. This process is laborious and becomes a major barrier for damage-compensated pruning decision-making, leading to too few live buds per vine and the associated excessive vigor and low yield that result. The overarching goal of this study was to develop an active thermographic system for non-destructive detection of bud damage in the vineyard.