WINETECH Technical Yearbook 2021

ACKNOWLEDGEMENTS The author would like to thank Prof. Maret du Toit and Prof. Benoit Divol from the South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Stellenbosch University for a critical review of this article. REFERENCES Du Bois, A., Shelton, M., Qian, M. & Osborne, J., 2021. Effect of malolactic fermentation and ageing on the concentration of p- cou- maric acid of Pinot noir wine and the con- sequence for volatile phenol production by Brettanomyces. Australian Journal of Grape and Wine Research 27: 81-86. https://doi. org/10.1111/ajgw.12464 Dugelay, I., Sapis, J.C., Baumes, R.L. & Bay- onnove, C.L., 1993. Role of cinnamoyl ester-

Other red cultivars, such as Cabernet Sauv i gnon , gene r a l l y have mo r e co l our ( anthocyan i n) than P i no t noir. Hydroxycinnamic acids, such as p- coumaric acid, can form complexes with anthocyanins to form stable pigments, thereby making the hydroxycinnamic acids unavailable for Brett metabolism. In fact, studies have noted decreases in p- coumaric acid over time, independent of Brettanomyces growth, which they attributed to co-pigmentat ion with anthocyanins. Unfortunately, it has been shown that Pinot noir has very low levels of co-pigmentation, which was confirmed in the Oregon State University study. PRACTICAL ADVICE The same as for the short answer.

2017. Influence of Oenococcus oeni and Bret­ tanomyces bruxellensis on hydroxycinnamic acids and volatile phenols of aged wine. American Journal of Enology and Viticul­ ture 68, 23-29. https://www.ajevonline.org/ content/68/1/23

ase activities from enzyme preparations on formation of volatile phenols during wine- making. Journal of Agricultural and Food Chemistry 41: 2093-2096. Smith, B.D. & Divol, B., Oct. 2016. Brettan­ omyces bruxellensis , a survivalist prepared for the wine apocalypse and other beverages. Food Microbiology 59: 161-175. https://doi. org/10.1016/j.fm.2016.06.008 Kallithraka, S., Salacha, M.I. & Tzourou, I., Mar. 2009. Changes in phenolic composi- tion and antioxidant activity of white wine during bottle storage: Accelerated browning test versus bottle storage. Food Chemistry 113(2): 500-505. https://doi.org/10.1016/j. foodchem.2008.07.083 Madsen, M.G., Edwards, N., Petersen, M.A., Mokwena, L., Swiegers, J.H. & Arneborg, N.,

For more information, contact Karien O’Kennedy at karien@winetech.co.za.

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