|SCHOPP, LAUREN - Washington State University|
|EDWARDS, CHARLES - Washington State University|
Submitted to: Washington Association of Wine Grape Growers Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2012
Publication Date: 2/15/2012
Citation: Schopp, L.M., Lee, J., Edwards, C.F. 2012. Differential metabolism of hydroxycinnamic acids by two Brettanomyces bruxellensis strains grown in red wines. Washington Association of Wine Grape Growers Annual Meeting. Kennewick, WA.
Technical Abstract: Hydroxycinnamic acids (caffeic, p-coumaric, and ferulic acids) and their corresponding tartaric acid esters (caftaric, coutaric, and fertaric acids, respectively) are found in red wines in varying concentrations depending on cultivars and other factors. While some Brettanomyces form volatile phenols from hydroxycinnamic acids to spoil wines, it is not known whether the yeast can metabolize the corresponding tartaric acid esters. Commercially-produced ‘Merlot,’ ‘Cabernet Sauvignon,’ ‘Pinot noir,’ and ‘Syrah’ wines were inoculated with two strains of Brettanomyces at 104 to 105 CFU/mL. Wine samples were fractioned by C18 SPE columns with acidic polyphenolics analyzed by High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD). ‘Cabernet Sauvignon’ and ‘Merlot’ wines had similar concentrations of caffeic acid (15-20 mg/L) and caftaric acid (3-5 mg/L), in contrast to ‘Pinot noir’ and ‘Syrah’ for these two phenolics (12-13 mg/L and 7-8 mg/L, respectively). Concentrations of coumaric acid (4-6 mg/L), coutaric acid (1-3 mg/L) and ferulic acid (0.5-1 mg/L) were similar for all wines. Even with slight differences in phenolic composition, growth of the two strains of Brettanomyces was similar between the four wines. For example, culturable populations of strain B5 slowly declined over nine weeks and did not metabolize hydroxycinnamic acids nor their esters in any of the wines. Conversely, strain I1a reached populations of 107 CFU/mL and, after four weeks, began metabolizing caffeic, p-coumaric, and ferulic acids but not the tartaric acid esters. Based on these results, B. bruxellensis may not be able to hydrolyze the tartaric acid esters of caffeic acid or p-coumaric acid. Future research will include two additional strains of Brettanomyces also isolated from Washington State wines. Furthermore, the ability of other wine microorganisms (e.g., Pediococcus sp.), containing esterase activity, to encourage Brettanomyces through hydrolysis of tartaric acid from caftaric, coutaric and fertaric acids will be studied.