Macrowine 2021
IVES 9 IVES Conference Series 9 Analysis of off flavours in grapes infected with the fungal bunch rot pathogens, Aspergillus, Botrytis and Pencillium

Analysis of off flavours in grapes infected with the fungal bunch rot pathogens, Aspergillus, Botrytis and Pencillium

Abstract

Fungal bunch rots of grapes cause major losses to grape yield worldwide, yet the impact these moulds have on grape and wine quality is not well characterised. We sought to investigate the formation of unwanted volatile compounds of fungal origin in both synthetic grape juice culture media and in inoculated grape berries. Botrytis cinerea, Aspergillus niger, Aspergillus carbonarius, or Pencillium expansum were grown in synthetic grape juice medium and the culture homogenates analysed 4 and 7 days post inoculation. HS-SPME-GC-MS analysis of the culture homogenates 4 days post inoculation demonstrated that each of the fungi examined produced varying quantities of the mushroom or fungus-like aroma compounds, 1-Octen-3-ol, 1-Octen-3-one and 3-Octanone with A. carbonarius producing up to ten times the amounts of all three metabolites per mg of dry mycelium. Geosmin, an off-flavour commonly associated with musty or mouldy aromas was only detected in the P. expansum culture 4 days post inoculation. Low levels of geosmin were also detected in the A. carbonarius culture 7 days post inoculation. Methylisoborneol (MIB), another metabolite associated with musty aromas was identified only in grape juice medium inoculated with B. cinerea. Detached surface-sterilised Vitis vinifera (cv. Chardonnay) berries (13.5 ⁰Bx) were inoculated by placing 104 fungal spores on to the apex of each berry. The concentration of 1-octen-3-ol was significantly higher in grapes inoculated with either A. carbonarius, or Penicillium expansum (range 204 – 850 ng/L) than in grapes inoculated with A. niger or B. cinerea (24.8 and 34.5 ng/L respectively) five days post-inoculation. Berries infected with A. carbonarius had the highest concentrations of methylisoborneol. Elevated levels of 1-octen-3-one were also observed in all inoculated berries. Berries inoculated with A. carbonarius had significantly higher levels of gluconic acid (16.3 g/L) compared to the other fungi (range 0.53 – 1.62 g/L). The results indicate that different fungal pathogens produce a similar range of off flavours but the relative proportions when expressed on a dry fungal mass basis when expressed with respect to ergosterol, v ary. This may in turn influence the sensory properties of wine made from different batches of bunch rot affected grapes.

Publication date: 17/05/2024

Issue: Macrowine 2016

Type: Poster

Authors

Christopher Steel*, Andrew Clark, John Blackman, Lachlan Schwarz, Leigh Schmidtke, Paul Tauvel

*NWGIC

Contact the author

Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

Related articles…

Characterization of non-Saccharomyces yeast and its interaction with Saccharomyces cerevisiae with investigation of fermentation kinetics and aromatic composition

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.20.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...

Assessing the effect of oak derived aromas on mouthfeel perception in Chardonnay wine

Mouthfeel is an important quality parameter for Chardonnay wines, particularly those aged in oak. While research on mouthfeel has traditionally focused on the impact of non-aromatic compounds, the role of aroma compounds has largely been over looked. However, in wine as well as other food interactions between retronasal aroma and mouthfeel have been noted. The goal of this research was to investigate the impact of wine aroma on the perception of mouthfeel. Because of the importance of oak aging in the development of Chardonnay mouthfeel, the impact of oak aromas on perceived mouthfeel was explored. Aroma compounds associated with oak (ethyl palmitate, eugenol, furfural, isoeugenol, syringaldehyde, vanillin and whiskey lactone) were added to two different Chardonnay wines; one with no oak influence and one fermented in neutral oak. Low and high concentrations of the compounds were added based on concentrations typically found in barrel aged Chardonnay wine.

Characterization of Glycosidically Bound Aroma Compounds of País cv. grapes of different Chilean zones

País grape has been estimated to arrive to Chile almost 500 years ago, being the first strain grown in this country. Traditionally, this grape has been used to mix with other varieties, to produce poor quality wines, but today is beginning to be used in the production of high quality wines. However, very little is known about the chemical characteristics of this variety. The aroma is one of the most important quality attributes of wine. Volatile compounds of this beverage may come from the grape (varietal aromas), from the fermentation process, from the ageing. The aromatic compounds are found in the grape in two forms: as free volatile compounds and as non-volatile compounds. The last ones, are aroma precursors present mainly as glycoconjugates formed by a sugar and an aglycone…

Petrolomics-derived data interpretation to study acetaldehyde-epicatechin condensation reactions

During red wine ageing or conservation, color and taste change and astringency tends to reduce. These changes result from reactions of flavan-3-ols and/or anthocyanins among which condensation reactions with acetaldehyde are particularly important. The full characterization of these reactions has not been fully achieved because of difficulties in extracting and separating the newly formed compounds directly from wine. Model solutions mimicking food products constitute a simplified medium for their exploration, allowing the detection of the newly formed compounds, their isolation, and their structure elucidation.

A preliminary study of clonal selection in cv. Viura in relation to varietal aroma profile

Viura is a synonym for Macabeo and currently it is the most widely planted white grape variety in D.O.Ca. Rioja, with 3,569 ha, representing 84% of the white grape cultivated area. It is a generous-yielding grape, presenting low values of titratable acidity and with large and compact clusters which makes it susceptible to Botrytis cinerea. Thus, this variety not always satisfies the wine grower’s prospects. Nowadays, the available plant material is scarce, moreover, it was selected on the basis of other quality criteria, not currently requested.