Unflavored Powdered Gelatin is a thickener that is activated by first dissolving the powder in cold water. Once heated, the dissolved gelatin forms a gel-like substance that will thicken and stiffen the mixture it is added to but it needs to time to chill and set up properly. Gelatin is often used to add body and substance to creams, mousses and in this book, panna cotta, which is a cooked cream dessert.