Mannoproteins
Yeast-derived colloids that steady tartrate and protein and add texture.
Typical dose
Per the product sheet, on a finished wine before bottling.
When to add it
Before the final filtration and bottling.
In practice
Released naturally during lees ageing and available as an addition, they interfere with both tartrate and protein crystallisation while rounding the palate, so they do several gentle jobs at once. They are a mild stabiliser rather than a guarantee, often used alongside a short cold stabilisation rather than instead of one.
Linked faults are the ones this addition either treats or, used wrongly, causes. The fault page says which, and whether it can be undone.
Others in tartrate and colloidal stabilisers
Metatartaric acid
A cheap, temporary block on tartrate crystallisation.
Carboxymethylcellulose
A durable tartrate stabiliser for whites and sparkling.
Potassium polyaspartate
A newer tartrate stabiliser that also works in red wine.
Bitartrate seeding
Seeds cold stabilisation so tartrate drops faster and more completely.