Winegrowers Supplies  -  Protein Stability testing

To ascertain whether a wine is 'protein stable' the following test can be used:-

Wine should remain unchanged in appearance after being held at 70 C (max 90 C) for 15 minutes, then subsequently cooled to 20 C.
Although this is sufficient, I usually then put the wine in a refrigerator for a few hours,  then remove and allow it to warm to room temperature again before re-examining.

There are chemical tests available, such as the Bentotest, but the above procedure subjects the wine to all likely handling.

One simple chemical test is: add about 50 mgms of tannin (5 ml of 1% tannin solution) to 100 ml of wine, if turbidity occurs there is excess protein.

Bentonite is used for protein stabilisation, fining and adsorption of undesirable substances in must (or wine).