Fermentation and wine quality studies

Fermentation and wine quality studies are performed to provide the wine industry with the knowledge and assurance that the active constituent or product applied during grape growing is not going to have a detrimental effect on fermentation or wine quality. Such an effect could include the formation of off-flavours or aromas due to the breakdown of the active constituent itself or changes in the fermentation kinetics.

The fermentation and wine quality study is often performed as part of the application for new active constituents to be considered for inclusion in the AWRI’s ‘Dog book’ as recommended for use on grapes destined for export wine. For further information on what agrochemical companies are advised to provide for this inclusion please refer to the following AWRI webpage: Guidelines for agrochemical registrants – The Australian Wine Research Institute.

Samples (same grape variety) should be taken from sites with a minimum of the following treatments:

• Untreated control
• 1 x label rate application
• 2 x label rate application

A minimum of 25 kg is required to be submitted for each sample or treatment in the study for triplicate ferments. Even if no detectable residues are present in the samples, the study can still proceed based on the possibility that the active constituent may have been converted to a secondary metabolite or broken down to another compound which may affect fermentation or wine quality. Additional treatments may also be introduced.

Fruit condition must be sound as wine made from spoiled, mouldy or unripe fruit will not be suitable for a fermentation or wine quality assessment. Fruit should be harvested at acceptable levels of ripeness unless otherwise stipulated in the trial and ideally the fruit should be at a similar level of maturity across the different treatments. It is strongly advised that samples be frozen or delivered as soon as possible after harvest as these studies rely heavily on good fruit quality to ensure the best outcome.

The Affinity Labs winemaking protocol followed for these studies reflect that of processing red varieties into wine, considered the ‘worse-case-scenario’ due to the skin contact employed in the process. This technique is not suitable for white grape varieties and tends to make wines which are quite unpalatable and not suitable for the sensory component of the study. Hence, it is strongly recommended that these studies are conducted on red grape varieties.

Wines are clarified before being presented to an in-house sensory panel for a balanced reference difference test in which comparisons between the untreated control and the treated samples are assessed. A final report is provided at the conclusion of the study that includes all winemaking kinetics data, chemical analysis and sensory results.

To discuss your fermentation and wine quality needs in more detail and obtain a project quote, contact our Project Team Manager, Kieran Hirlam on 08 8313 0444 or complete the enquiry form below.