Question

Genetic engineering of microorganisms involved in MLF of wine has only been partially successful, why?

Answer 1

MLF is an integral part of winemaking, resulting from the metabolic activity of LAB. It gives the final wines better palatibillity by partial successful that reducing the tart taste associated with mallic acids and provides additional improvements, like microbial stability and enhanced aroma complexity. The role of MLF in winemaking is threefold, they are reducing wine acidity, stabilizing wine through removal of a potential carbon source, and producing aroma and flavour changes. Microorganisms ability to survive the harsh conditions of wine and production of desirable sensory compounds makes it the choice.

The wine may be seeded with the required organism or or use a natural source that performed by inoculation during yeast fermentation. It is essential that the wine is checked regularly for the growth of unwanted microorganisms especially oxidative film yeast that leads to acetaldehyde formation. If sulphur dioxide is present during MLF it increases the potential for spoilage. Infact, from a biochemical standpoint, it is not really a fermentation process, it is like alcoholic fermentation. The biomass of LAB that develops in wine , after yeast has declined and slowly disappeared, decarboxylates mallic acids to form lactic acid. Some enhance quality, whiles others may be detrimental to sensory qualities or undesirable for health. It concerns very small amounts of substrates and products that will not be identified untill the chemical changes before and after MLF have been elucidated. Micro, pick and even nanomolar concentrations of this have an impact on quality.