It is commonly used as a gelling agent in food.
Gelatin for cooking and dessert preparations come in the form of sheets or powdered granules.
Typically the household form more commonly used is the powdered granular variety, whereas in the professional kitchen it is more often Sheet Variety.
Since we must BLOOM the gelatin to activate its properties, I use this rule of thumb: If the liquid you are blooming the gelatin in, is intended to go in the recipe, powdered is the more efficient choice since you will bloom it in the liquid called for in the recipe (alcohol, purees, juices etc) melt it all together and add to the recipe as one entity.
But if there is not a liquid to enhance the recipe, sheets can be easily bloomed in ice water, then simply rung out of the excess water, melted and proceed to add to the recipe as called for.
THE RATIO OF POWDERED GELATIN TO SHEETS is:
Powdered-Sprinkle the granules of gelatin over the surface cold water or liquid (sometimes fruit purees are used).
Use 1/4 cup water per envelope OR whatever amount of liquid that the recipe states. Let stand for 5 to 10 minutes. This is called the “blooming” process. Then gelatin granules are like tiny molecular balloons that fill up with the liquid. Once all the liquid has been absorbed, you are left with a slushy mixture that will need to be heated to dissolve the gelatin to then use in your recipe.
Heat gently on the stove or in the microwave for just about 15 seconds at a time, stirring until dissolved. Do not boil.
Sheets- Gelatin sheets are primarily used in recipes that call for a warm or hot liquid preparation such as Panna Cotta and some mousses but can be used in cold preparations also.
Soak sheets of gelatin submerged in a bowl cold water for 5 to 10 minutes. The quantity of water is not important, as you will discard the water that has not been absorbed.
Once soft, remove sheets from the cold water and wring gently to remove excess water then add to recipe as stated. If adding to a cold mixture, melt the softened sheets in a saucepan or microwave over very low heat, stirring just until melted completely. Then stir in the cold mixture.
Gelatin is graded by “bloom” which is the strength of the gelatin. Since Knox brand gelatin is the most used brand and it has a 225 bloom, I would recommend the Gold Gelatin Sheets since they have about 200 bloom. This way we are staying within the range listed here as far as interchangeability.
1/4 ounce envelope of plain gelatin = 2 1/2 teaspoons (10g)
1 envelope of gelatin will set 2 cups of liquid in a recipe
1 envelope Or 2 1/2 teaspoons powder =3 sheets
Certain tropical fruits, such as pineapple, kiwifruit, and ginger, have an enzyme (bromelin) that can prevent gelatin from setting. Heating the fruit completely through before using will destroy the enzyme.
**For vegetarian substitutions see Agar