Video-Winemaking trials with sooty mould

2018 ASVO Seminar; Frontline pest and disease management for healthy vineyards
Sooty mould winemaking trial: the impact on processing, composition and sensory attributes of Shiraz wine

Peter Godden, The Australian Wine Research Institute (AWRI)

A winemaking trial was conducted in vintage 2017 to investigate the effects of sooty mould infection of Shiraz grapes on the properties of the wines made from those grapes. Three fermentation treatments were conducted: a non-sooty mould-affected control and ferments with 5% and 25% sooty mould infection respectively. At destemming and crushing, more colour was evident in the sooty mould-affected must, suggesting that the sooty mould might have infiltrated the grape skins. No consistent differences were evident in must analysis post-crushing, except for a small reduction in sugar concentration with increasing sooty mould. Few differences were seen in wine analysis, except for slightly lower alcohol concentrations with increasing sooty mould, lower concentrations of free and total SO2 in the 25% sooty mould‑affected treatment and a decreasing ratio of free to total SO2 with increasing sooty mould. Phenolics analysis revealed an increase in non-bleachable pigments with increasing sooty mould, with consequent reduction in anthocyanin concentrations. No differences between the control wine and the 25% sooty mould-affected treatment were observed during sensory evaluation. Wine yield was not affected by the presence of sooty mould, although the sooty mould appeared to inhibit settling. The presence of sooty mould resulted in an increase in lees solids and in lees dry weight, with the concentrations of both yeast and plant-derived polysaccharides in the lees increasing with increasing sooty mould. While the presence of sooty mould had little effect on the sensory properties, chemical composition or processing of the wines in this trial, it should be noted that the condition and careful selection of the fruit used might represent an atypical situation in a commercial setting.