Everything you need to know about yeast mannoproteins (INS455)

dans le vin

Derived from yeast cell walls, yeast mannoproteins play a key role in stabilising and clarifying wines. Find out how they are used in winemaking.

Used for several decades in oenology, these proteins can play a discreet but essential role in the final quality of bottled wine. In addition to their stabilising effect , they can also provide subtle benefits in terms of taste.

What are yeast mannoproteins?

Mannoproteins are proteins naturally present in yeast cell walls. They are gradually released into wine during alcoholic fermentation, a process during which the sugars in the must are converted into alcohol, and during the barrel ageing of certain white wines.

These proteins are therefore entirely natural and emerge directly from the life cycle of the yeasts used in winemaking. In oenology, their targeted use enables their unique properties to be exploited to stabilise and clarify wine.

Why are yeast mannoproteins added to wine?

Mannoproteins are mainly used to prevent the formation of tartaric crystals in wine bottles, a phenomenon that can lead to unsightly deposits. By enhancing the clarity of wines (as can metatartaric acid, carboxymethylcellulose and potassium polyaspartate), they improve a wine’s appearance and enhance the tasting experience.

They also play a stabilising role, extending the life of a wine while preserving its organoleptic characteristics. In addition, in some cases they can slightly improve the roundness and texture of the mouthfeel.

More specifically, how do these ingredients stabilise wine?

Mannoproteins act directly on tartaric crystals forming in wine. By attaching themselves to these crystals, they prevent them from growing and clumping together, thus avoiding the creation of visible deposits in the bottle.

This mechanism is particularly important for white, rosé and sparkling wines, which are more susceptible to tartaric deposits because of their chemical profiles.

How are these stabilisers used by the winemaker?

Yeast mannoproteins are added to wine after fermentation, just before bottling. This timing is crucial, as it ensures that the wine has reached its final balance in terms of flavours and aromas before being stabilised.

The doses used are precise and calculated in accordance with current regulations. This ensures that the treatment is effective without altering the wine’s taste or identity.

Apart from in bottles of wine, can these oenological products be found elsewhere?

Although mannoproteins are mainly used in oenology, they also have applications in other fermented beverages, such as beer. In this context, they also help to stabilise the product and improve its visual appearance.

Whether used in wine or beer, yeast mannoproteins illustrate how natural processes can be harnessed to enhance the characteristics of fermented beverages.