When should innoculation be carried out?
Various inoculation methods exist:
- Early co-inoculation, which consists of adding bacteria 24 to 48 hours following the yeast addition (or fermentation onset if the alcoholic fermentation is indigenous). This method helps ensure a rapid start for MLF in many cases. Sometimes MLF even starts at the end of alcoholic fermentation.
- Delayed co-inoculation, which consists of adding the yeast at a density of approximately 1010. There is a longer acclimatization time and MLF starts a few days or weeks after the end of alcoholic fermentation.
- Sequential inoculation. This is a more traditional inoculation that is done just after the alcoholic fermentation. The bacterial adaptation time is then longer.
- Inoculation for fermentation recovery (curative). This is the method with the longest time lag and also the most widely used method. The vast majority of wines are vinified with indigenous MLF. The use of lactic acid bacteria is then only done if problems arise, and therefore very late. At this stage, there is often indigenous flora competing with the added bacteria. The success of inoculation is not always guaranteed.
Finally, in the case of indigenous MLF, it is possible to inoculate a batch with the lees or a small volume of another batch that has started its MLF successfully. This avoids the use of commercial bacteria while still ensuring rapid MLF. However, beware of cross-contamination with spoilage organisms.