Delayed malolactic fermentation: exploring the stylistic and practical impacts

Though almost universally referred to as malolactic fermentation, the process through which tart-tasting malic acid is converted to softer tasting lactic acid and carbon dioxide released is not technically a fermentation. More accurately it is a conversion or transformation. Though likely as old as wine itself, practical understanding of malolactic is a relatively recent breakthrough. As early as 1837 German oenologist Freiherr von Babo described a “second fermentation” which resulted in increased turbidity. Von Babo’s advice to winemakers was to immediately rack their wines and add sulfur to stabilise. Following a string of influential breakthroughs in the late ’80s, in 1939 the French wine scientist Émile Peynaud outlined the importance of malolactic in making great Bordeaux. By 1960, following work by scientists in California, France, and Portugal, isolated strains of lactic acid bacteria were successfully used to carry out malolactic fermentation in the winery. Nowadays winemakers have a range of malo-centric variables at their disposal. Some choose to inoculate with bacterial cultures while others opt for spontaneity, some experiment with particular cultures of bacteria while others negate warming with site-specific blocking of malolactic. And though not often discussed, there are those who consider delayed malolactic fermentation as being amongst the most impactful of these variables. In this piece, I explore this topic in more detail with the help of some of the worlds most-lauded winemakers and writers.