VINEYARD MANAGEMENT PRACTICES AND THE QUALITY OF GRAPES AND GRAPE PRODUCTS IN THE PACIFIC NORTHWEST
Location: Horticultural Crops Research
Title: Metabolism of hydroxycinnamic acids and esters by Brettanomyces in different red wines
Submitted to: American Society of Enology and Viticulture Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2012
Publication Date: June 18, 2012
Citation: Schopp, L.M., Lee, J., Edwards, C.G. 2012. Metabolism of hydroxycinnamic acids and esters by Brettanomyces in different red wines. American Society of Enology and Viticulture Annual Meeting Abstracts. Meeting Brochure.
Depending on the cultivars and other factors, differing concentrations of hydroxycinnamic acids (caffeic, p-coumaric, and ferulic acids) and their corresponding tartaric acid esters (caftaric, coutaric, and fertaric acid, respectively) are found in red wines. Hydroxycinnamic acids are metabolized by Brettanomyces to form volatile phenols recognized to spoil wines. However, it is not proven if Brettanomyces can metabolize the corresponding tartaric acid esters. Populations of 104 to 105 CFU/mL of two strains of Brettanomyces were added to commercially-produced Cabernet Sauvignon, Merlot, Pinot noir and Syrah wines. Acidic polyphenolics were analyzed by HPLC with diode array detection after fractionation by C18 solid phase extraction columns. Prior to inoculation, concentrations of caffeic and caftaric acids were similar between Cabernet Sauvignon and Merlot (15-20 mg/L caffeic and 3-5 mg/L caftaric), and between Pinot noir and Syrah (12-13 mg/L caffiec and 7-8 mg/L caftaric). For all the wines, concentrations of p-coumaric acid (4-6 mg/L), coutaric acid (1-3 mg/L) and ferulic acid (0.5-1 mg/L) were comparable. In all four wines, culturable populations of strain B5 declined similarly over nine weeks while concentrations of hydroxycinnamic acids and the tartaric acid esters remained unchanged. Conversely, strain I1a reached populations of 107 CFU/mL in all the wines and metabolized varying amounts of caffeic, p-coumaric, and ferulic acids after four weeks. Concentrations of the tartaric acid esters did not change in wines inoculated with I1a, analogous to B5. 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. Furthermore, the encouragement of Brettanomyces growth through the hydrolysis of tartaric acid from caftaric and coutaric acids by other wine microorganisms (e.g., Pediococcus sp.) will be studied.