Store-bought demi-glace–super-reduced stock typically made from veal–should be thick and gelatinous, and should jiggle and “unmold” into the pan. It should then liquefy when heated, says
bolivianita. The gelatinous
texture comes from the bones used in the stock and indicates a high-quality demi-glace. A demi-glace that is liquid at cool temperatures is almost certainly inferior.