Aubrey DuBois, Stuart Chescheir, and James Osborne*  
*Department of Food Science and Technology, Oregon State University, 3051 SW Campus Way, Corvallis, OR 97331 (james.osborne@oregonstate.edu)

Wine is particularly vulnerable to Brettanomyces infection during and shortly after malolactic fermentation (MLF), as SO2 cannot be added until this process is complete. Conducting a rapid MLF initiated by inoculation of a commercial Oenococcus oeni strain is a useful strategy to prevent Brettanomyces spoilage, as this minimizes the length of time the wine is not protected by SO2. Previous research in our lab demonstrated that B. bruxellensis growth was hindered by the presence of live O. oeni cells present post-MLF. The current study investigated how long this inhibition persisted post-MLF. Pinot noir wine was inoculated for MLF with three commercial O. oeni strains and B. bruxellensis was inoculated into the wine 0, 30, and 100 days after completion of MLF. O. oeni populations in the wines were still high directly after completion of MLF, and B. bruxellensis populations declined rapidly after inoculation. Thirty days post-MLF, high populations of two O. oeni strains were still present in the wine but no culturable cells were detected in the wine for the third strain. When B. bruxellensis was inoculated into the wine containing no culturable O. oeni cells, it grew well. In contrast, B. bruxellensis populations declined rapidly when inoculated into wine where there were still culturable O. oeni cells. One hundred days post-MLF, no culturable O. oeni cells were detected in any wines and B. bruxellensis grew well in all but one wine. These findings suggest that MLF may offer limited protection against B. bruxellensis infection due to the presence of live O. oeni cells. Additional work is being conducted to determine whether other B. bruxellensis strains are also sensitive to the presence of live O. oeni cells.

Funding Support: Northwest Center for Small Fruits Research