Project title
The occurrence of malolactic fermentation in rebate wine and its influence on brandy quality

Project leader
Du Toit, M

Institution
University of Stellenbosch. Institute for Wine Biotechnology

Team members
Lambrechts, M G
Muller, C A
Steger, C L C

Project description
The aims of this study are to investigate the extent to which malolactic fermentation does occur in South African rebate wine. To investigate whether and to what extent, a rebate wine having undergone malolactic fermentation differs organoleptically before and after undergoing double distillation to a 70% volume strength wine spirit.

In producing an acceptable base wine to be used for distillation into brandy, no sulphur dioxide may be added to the must or wine at any stage of its production. As sulphur dioxide is the winemaker's most effective antioxidative and antimicrobial agent, base wines thus become far more susceptible to spoilage via oxidation and by microbial activity. Many of the base wines are also often forced to spend considerable periods of time in storage tanks, as the distilleries try to cope with the large influx of wine arriving continuously during harvesting season. Yeast autolysis can occur resulting in the release of nutrients that facilitate the growth of lactic acid bacteria during this period. The chances of lactic bacteria being present in the wine and performing malolactic fermentation are thus high.

The sensory qualities of wines, especially white wines having undergone malolactic fermentation (MLF), may vary considerably. Recent studies have also indicated that the malolactic strain used may also profoundly alter the sensory qualities of the wine. Although this change is largely a consequence of the resultant increase in pH, lactic acid bacteria can produce other compounds such as acetaldehyde, diacetyl, acetic acid and acetoin, and are also able to convert diacetyl to 2,3 butanediol. These compounds may all affect the organoleptic qualities of the wine.

Presentation(s)
1. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M and Pretorius, I S. 1999. The occurrence and influence of lactic acid bacteria on the quality of brandy base wine. 24th International Wine Congress, Mainz, Germany.
2. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M and Pretorius, I S. 1999. Lactic acid bacteria and their effect on brandy base wine. 17th International Committee on Food Microbiology and Hygiene, Veldhoven, The Netherlands.
3. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M, Dicks, L M T and Pretorius, I S. 1999. Occurrence and characterisation of lactic acid bacteria in base wines for brandy making. 24th National Congress of the South African Society for Enology and Viticulture, Cape Town.
4. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M, Dicks, L M T and Pretorius, I S. 2000. The occurrence and characterisation of lactic acid bacteria in brandy base wine. 2nd International Congress of the South African Society for Enology and Viticulture, 13-15 November, Cape Town, South Africa
5. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M, Dicks, L M T and Pretorius, I S. 2000. The occurrence and characterisation of lactic acid bacteria in brandy base wine. BioY2K Combined Millennium Meeting, Grahamstown.
6. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M and Pretorius, I S. 2002. The influence of malolactic fermentation on brandy aroma. 26th National Congress of the South African Society for Enology and Viticulture. 13-15 November, Somerset West, South Africa.
7. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M, Dicks, L M T and Pretorius, I S. 2003. The occurrence of malolactic fermentation in brandy base wine and its influence on brandy quality. 1st FEMS Congress of European Microbiologists, Ljubljana, Slovenia.
8. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M and Pretorius, I S. 2004. The impact of malolactic fermentation on South African rebate wine. 12th Australian Wine Industry Technical Conference, Melbourne, Australia.
9. Lambrechts, M G, Du Plessis, H W, Steger, C L C, Du Toit, M, Dicks, L M T and Pretorius, I S. 2004. The occurrence of malolactic fermentation in brandy production. 13th Congress of the South African Society for Microbiology, Stellenbosch.

Final report
http://www.sawislibrary.co.za/dbtextimages/finalreport15.pdf

Du Plessis, H W, Steger, C L C, Du Toit, M A, Lambrechts, M G. 2002. The occurrence of malolactic fermentation in brandy base wine and its influence on brandy quality. Journal of Applied Microbiology. v. 92 n. 5 p. 1005-1013

Article

Du Plessis, H W, Dicks, L M T, Pretorius, I S, Lambrechts, M G, Du Toit, M A. 2004. Identification of latic acid bacteria from South African brandy base wines. International Journal of Food Microbiology. v. 91 n. 1 p. 19-29

Du Plessis, H W, Snyman, C L C, Du Toit, M A, Lambrechts, M G. 2004. Die voorkoms van appelmelksuurgisting in Suid-Afrikaanse rabatwyn. WineLand. Mnth Apr p. 81-82

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