Malolactic Conversion

Appears in
Oxford Companion to Wine

By Jancis Robinson

Published 2006

  • About

malolactic conversion, widely known as malolactic fermentation, and often abbreviated to MLF or malo is the conversion of stronger malic acid naturally present in new wine into lactic acid (which has lower acidity) and carbon dioxide. The term conversion is more accurate because it is not literally a fermentation process, although the release of carbon dioxide may initially give that impression. It is accomplished by lactic acid bacteria, which are naturally present in most established wineries but may have to be cultured and carefully introduced in newer establishments where malolactic conversion is desired. This process is unrelated to and almost never precedes the main, alcoholic fermentation, for which reason it is sometimes called a secondary fermentation. Nevertheless, it is not uncommon for malolactic conversion to be complete by the end of the alcoholic fermentation.