To perfectly manage malolactic fermentation, the very first step is to collect data related to the following set of primary parameters using some key analyses and investigations. The list is longer than for alcoholic fermentation because, while the grape juice is naturally a very favorable environment for yeasts, bacteria or mold development, the wine or must is much harsher environment for lactic acid bacteria.
The primary set of parameters comprises: pH, total sulfites, ethanol and temperature.
Total sulfites, and consequently free sulfites, will determine the level of molecular sulfites that will inhibit and even kill a part of the lactic-acid bacteria. The lower the pH, the higher is the molecular sulfur level for a constant level of total sulfites. As a general rule, one can now state that the lower the sulfur level is at inoculation time, the better it is for the microbial population that will be inoculated, and therefore fermentation management.
The next couple of parameters are ethanol and temperature. The effect of ethanol on bacteria is enhanced as temperature rises. Temperature at inoculation should never be higher than 25 °C, a principle often forgotten in wineries managing MLF during AF or in the tail of AF.
The secondary set of parameters is made up of important data and information that must be checked before inoculation: organic nitrogen available for bacteria, absence of medium-chain fatty acids (C8, C10, C12), TPI (Total Polyphenol Index) and even the yeast used during AF and their ability to produce sulfites.