Fermentation management through optimal microbial consortia

Summary

Objective

This work will build on existing capacity and encompass interactions between non-Saccharomyces yeast, S. cerevisiae yeasts and wine bacteria. We will also seek to identify regimes of nutritional supplementation that will support successful microbial relationships and identify compounds responsible for antagonistic relationships. Nutritional work will include, but not be limited to, recycling of fermentation end-products as nutritional supplements. In undertaking this work, we hope to further optimise process control, from maceration and bioprotection to the timing and efficiency of malolactic fermentation, while reducing reliance on externally sourced fermentation aids.

This project will provide options for winemakers seeking to optimise fermentation performance while also providing opportunities to explore alternative approaches to ferment scheduling and strain selection. It will contribute to decreased wine production costs through building knowledge that will enable more efficient resource utilisation and increased fermentation efficiency.

Background

An ideal fermentation for wine is short, typically lasting no longer than a week. When fermentations become protracted, the delays can have a direct effect on the scheduling of winery operations. Worst-case scenarios may see residual sugar concentrations failing to meet production specifications, resulting in time-consuming and potentially expensive remediation actions.

Fermentation management has always been and continues to be, core business for any productive winery. It is complicated by the different types of fermentation employed (alcoholic and malolactic), the mode of those fermentations (concurrent or sequential, inoculated or not), the styles of wine being made (red or white, cellar bright juice or high solids) and the composition of the fermentation substrate (high YAN or high sugar) to name a few. These choices have the potential to shape fermentation outcomes and can lead to unpredictability in both the overall duration and completeness of fermentation.

This project will investigate the microbial interactions that support, or sometimes inhibit, efficient fermentation, and seek to identify microbial interactions that are maximally beneficial and minimally antagonistic. This will add to the comprehensive work that has previously been undertaken in defining the nutritional and operational factors that can be used to manage fermentation. 

This project builds on findings from previous research in AWRI 1701-3.2.2 (The relationship between grape juice composition and the progress of alcoholic and malolactic fermentation) and AWRI 1701-4.4.3 (Bioprospecting Australian microbial genetic diversity).