• Universitat de València

The winemaking process of still wines includes two stages carried out by microorganisms, alcoholic fermentation (AF) and malolactic fermentation (MLF). AF is carried out by yeasts, mainly Saccharomyces cerevisiae. In this fermentation, the sugars in the must are converted into ethanol. MLF is carried out by lactic acid bacteria (LAB), mainly by Oenococcus oeni, where L-malic acid is converted into L-lactic acid and CO2 is released. To ensure that these fermentations take place in the appropriate way, previously selected starter cultures are generally used. Usually, MLF takes place after AF is completed, but co-inoculation (simultaneous inoculation) of yeast and lactic acid bacteria is now being conducted so that AF and MLF occur simultaneously, which considerably reduces the winemaking time. During the ageing process in wooden barrels, the wine undergoes important physico-chemical modifications of an oxidative nature, which improve its organoleptic characteristics. These modifications produce phenomena such as the polymerisation of polyphenolic compounds, mainly tannins, and the transfer of compounds from the oak wood to the wine. This stage of wine ageing in barrels makes wine production very expensive due to the price of the barrels and the time required for ageing. In recent years, various alternatives to barrel ageing have emerged, one of which entails the use of oak wood shavings or chips, which are introduced during or after AF. These are new techniques that make it possible to achieve the benefits of barrel ageing, but in less time and at a lower cost.

On the other hand, during the sparkling wine production process, the yeasts carry out two successive fermentations, the first one in tanks and the second one in the bottle. At the end of the second fermentation process, the yeasts that carry it out are removed from the bottle through the disgorging process.

In the winemaking processes of still and sparkling cava-type wines, the immobilisation of yeasts and/or bacteria on oak wood supports provides numerous advantages, since the immobilisation support protects the microorganisms, mitigating their loss of activity and consequently reducing fermentation time. Furthermore, immobilisation allows the microorganisms to be easily removed from the wine or cava once the process is finished and, in addition, the shavings provide additional organoleptic improvements to the final product.

Researchers at the Universitat de València have developed a new method for immobilising yeasts and/or winemaking bacteria on a support of oak shavings or chips coated with starch. These yeasts and bacteria can be immobilised separately or together depending on whether the oenologist prefers to carry out AF and MLF successively or simultaneously. The use of co-immobilised yeasts and bacteria shortens the winemaking time of still wines. In addition, the shavings give the wine aromas and flavours of oak wood. In sparkling wines, the yeasts from the second fermentation of cava can be immobilised on these oak chips, which facilitates the process of their subsequent removal; in addition, the chips provide new organoleptic properties to the cava or sparkling wine.

The main application of this invention is in the field of oenology, specifically in the winemaking process to carry out the following fermentations:

• Alcoholic fermentation in red or white musts, with organoleptic contribution from wood.
• Malolactic fermentation in red or white wines, with organoleptic contribution from wood.
• Simultaneous alcoholic and malolactic fermentation in red or white winemaking, with organoleptic contribution from wood.
• Second fermentation in sparkling wines and cavas, with organoleptic contribution from wood.

The main advantages provided by the invention are:

• Alcoholic fermentation and malolactic fermentation in still wines can be carried out more safely and quickly than using non-immobilised cultures.
• Simultaneous alcoholic and malolactic fermentation in still wines.
• Providing oak wood properties to still wines, eliminating or reducing the stage in wooden barrels.
• Simplification and reduction of the time and costs of the winemaking process.
• Use of a natural immobilisation support accepted by the International Organisation of Vine and Wine and the European legislation: oak wood shavings.
• Elimination of the use of adjuvants, such as bentonite, to remove yeast from the bottle after the second fermentation of sparkling cava-type wines.

• Patent granted