Modelling relationships between visible winegrape berries and bunch maturity

Background and Aims: Rapid and non-destructive techniques for measuring grape composition have the potential to improve harvest decisions and to allow the batching of fruit into parcels of similar composition to improve processing efficiency. If such techniques are to be based on the non-destructive assessment of visible berries, then relationships between the composition of visible berries and that of the whole bunch will need to be described. Methods and Results: Total soluble solids, pH, TA and the concentration of anthocyanin, phenolic substances and tannin of visible berries and associated entire bunches of Shiraz and Chardonnay were measured over three seasons. Good correlations were obtained between the composition of visible berries and that of the entire bunch. Most relationships were not 1:1 but were consistent and stable across seasons. Conclusions: The accuracy and stability across the seasons of relationships between the composition of visible berries and that of the entire bunch for both Chardonnay and Shiraz were evaluated. Significance of the Study: The approaches used in this study to predict bunch composition from visible berry composition could aid the development of non-destructive techniques based on sensing visible berries to assess grape composition during ripening.