Cream of tartar is used to promote the formation of invert sugar during the cooking of sugar solutions. This produces a cooked sugar paste that is both glassy and keeps well (does not crystallize or clump). Be careful with the dosage of the product: if there is too much cream of tartar, there is a risk of yellowing or caramelizing the sugar and making it too hygroscopic during storage. On the other hand, if there is not enough cream of tartar, there is a risk of the sugar curdling on the cold table. You must also be careful not to exceed the cooking temperature of the sugar to prevent it from curdling on the hob or caramelizing. Cream of tartar also prevents egg whites from curdling during whipping.
