Optimising grape quality and value to improve vineyard profitability and sustainability

Summary

Objectives

To determine if new techniques to measure grape aromatic potential can be used to predict the optimum harvest dates for the production of desired red and white wine styles. The project aims to provide growers, grower-winemakers and companies with recommendations and solutions for easy to use and non-expensive online harvest decision methods.

Background

Earlier work has shown that the ‘berry aromatic sequence’ can be used to predict the optimum timing of harvest according to potential aromatic development during ripening. In white grapes, the commercially available ‘Dyostem’ tool is used to measure berry colour evolution as an indicator of aromatic properties. In  red grapes, the approach uses the concept of sequential harvest in association with fruit physiological indicators such as berry sugar and anthocyanin accumulation to determine the optimum harvest time according to the desired wine style. The two targeted ripening stages to be studied are described in the model as ‘fresh fruit’ and ‘mature fruit’ and correspond to defined time periods during ripening, after the point at which sugar loading per berry reaches a plateau. Such approaches are relatively new in the Australian wine industry, although they have been used successfully in commercial vineyards in Europe, South America, USA, and South Africa.

Scope

Experimental work will be based in Shiraz and Cabernet Sauvignon vineyards at Griffith, Orange and in  South Australia. Chardonnay will be studied in Orange and Tumbarumba, NSW. Through sequential harvesting, both small lot and small commercial  winemaking and testing of a suite of compositional parameters, the investigation aims to identify key marker compounds (e.g. anthocyanins, carotenoids, lipids, and amino acids) for specific wine styles and to identify the links between grape and wine composition and sensory characteristics.

Industry Benefit

This project will provide growers with an opportunity to manipulate fruit quality / composition / colour and allow the prediction of harvest dates 10-40 days in advance. Determination of fruit composition in relation to the desired wine style will also be able be better understood and managed. A decrease in production costs is also possible due to better vineyard and cellar management protocols including irrigation, decreased grape maturation time and cellar logistics. In the case of ‘fresh fruit’ styles, earlier harvesting will help to produce lower alcohol wine with different and possibly more desirable aromatic profiles.