The Tartrate Stability Index (TSI) is an analytical method by which different mannoproteins can be measured for their activity in wine. The technique compares the ability of different types of mannoproteins to prevent potassium tartrate crystal formation in a standard unstable wine held at -4°C for several days. Mannoproteins which prevent potassium tartrate crystal formation for at least 6 days at -4°C are classified as high TSI mannoproteins. The less effective mannoproteins are classified as low TSI.

The high TSI mannoproteins are predominantly found concentrated in specific parts of the yeast cell.
DSM's patented technology allows to extract, then fractionate the mannoproteins in order to isolate those with the highest TSI. Claristar™ high TSI mannoproteins are then purified to remove any haze-forming compounds and maintained in their natural hydrated state for improved efficiency.