Assessment of relationships between grape chemical composition and grape allocation grade

Summary

Objectives:

To determine from a range of measurable chemical compounds in grapes which of the measures, independently or in combination, are able to differentiate between grape grades.

Background:

The value of grapes is currently assessed in a wide range of ways. Typically this is through either field-based assessment of the condition of the vines, flavour of the fruit, presence of disease, some quantitative chemical measures or based on the final value of the wine that is achieved using those grapes. For the grower, this assessment determines how much they will get paid. For the winemaker, this assessment is critical to ensuring they have fruit that is appropriate to the value and style of the wine they intend to make as well as controlling raw material costs.

Subjectivity in this assessment can result in uncertainty as to whether the maximum value possible for those grapes is achieved. As such, many growers and winemakers want to support this decision making process by using objective chemical measures that are directly related to attributes that confer value such as key compounds responsible for taste, aroma, texture and appearance.

Research approach:

Grapes from a range of quality grades will be sourced by representative sampling of vineyards and a range of chemical analyses performed to determine the concentration of key compounds known to affect wine style and key sensory properties. The grade would be sourced from the grower or winery contracted to make wine from those grapes. Univariate or multivariate relationships will be determined among the chemical measures and the grades to assess the extent to which these measures are able to be used to predict the grade.

Industry Benefit:

Knowledge generated from this project will allow grape and wine producers to assess the practical application of objective chemical measures for grape quality grading.