Thresholds for Botrytis bunch rot contamination of Chardonnay grapes based on the measurement of the fungal sterol, ergosterol

Research output: Contribution to journalArticlepeer-review

Abstract

Background and Aims: The threshold for Botrytis contamination of winegrapes is not fully known. Using a measurement of the fungal sterol, ergosterol, we aimed to understand how much grey mould of grapes can be tolerated before there is a
perceivable impact on wine sensory characteristics.
Methods and Results: Chardonnay grape bunches hand-harvested in January 2016 from the Hunter Valley, NSW, were divided into one of five groups based on the visual assessment of the severity of grey mould using a scale of 0–4. Ergosterol analysis indicated that the fungal biomass of the five batches of grapes was 0.06, 0.28, 0.87, 1.50 and 4.25 g dry mass of fungus
per kg wet mass. Grey mould infection resulted in an elevated concentration of benzaldehyde, 2-pentyl furan, ethyl linoleate,
(E)-3-hexenol, 3-octanol, 1,5-dimethyl-naphthalene, 1,5-dimethyl tetralin 1-octen-3-ol, 1-octen-3-one and 3-octanone in the juice. 1-Octen-3-ol, and 3-octanone, ethyl-3-hydroxydodecanoate and isoamyl acetamide were elevated in wine made with Botrytis-affected grapes. Sensory discrimination tests identified a difference between wine made from grapes with ≥0.87 g of dry mass of fungus/kg wet mass of grapes (equivalent to ≥2.57 mg ergosterol/kg grapes) and wine made from asymptomatic grapes.
Conclusions: Ergosterol correlated with the degree of grey mould contamination and the threshold in Chardonnay grapes was 0.28–0.87 g dry mass fungus/kg fresh mass of grapes. Significance of the Study: Measurement of ergosterol has been evaluated as a quantitative estimate of the threshold for Botrytis contamination of winegrapes.
Original languageEnglish
Pages (from-to)79-89
Number of pages10
JournalAustralian Journal of Grape and Wine Research
Volume26
Publication statusPublished - 2020

Fingerprint Dive into the research topics of 'Thresholds for Botrytis bunch rot contamination of Chardonnay grapes based on the measurement of the fungal sterol, ergosterol'. Together they form a unique fingerprint.

Cite this