Gelatin is available in two forms: powder and sheet (leaf). It is thermo-reversible, meaning the setting properties or action can be reversed by heating. Gelatin is a water-soluble protein extracted from animal tissue and used as a gelling agent, a thickener, an emulsifier, a whipping agent, a stabilizer, and a substance that imparts a smooth mouth feel to foods. Powder or sheets (leaves) dissolved in cold water Added to cold or simmering liquid Activates with heat, sets when coldĭerived from collagens in bones and meats of animals Used in aspic, glazes, cold sauces, and desserts Clear, firm texture Dissolves when reheated, thickens when cold
Used when thickening liquids that might lose color or flavor during cooking Become viscous without the need for additional cooking Translucent, fairly clear, shiny, does NOT gel when coldĭerived from cassava root Used in Asian cuisines Very clear possesses a gooey texture Translucent, shiny, very light gel when cold Powder, dissolved in cold liquid 20-40 g starch thickens 1 L liquid Modified starches are often used in commercially processed foods and convenience products Modified to improve specific characteristics (e.g., stability or texture under extreme conditions heat and freezing) Translucent, thickens further as it cools Used in desserts and dessert sauces Clear, does not thicken further as it cools Does not gel at cool temperatures, good for cold sauces Quite stable at extreme temperatures (heat and freezing) Powder dissolved in cold water Added to cold or simmering liquid Activates with heat, sets when coldĮxtracted from seaweed Used in Asian desserts and molecular gastronomy cooking Used in place of gelatin in vegetarian dishes Clear firm texture Does not thin when reheated, thickens more when coldĭissolved in cold water 20-40 g starch thickens 1 L liquidĪdded to hot liquid while whisking until it dissolves and the liquid thickens Used to thicken sauces when a clear glossy texture is desired, such as dessert sauces and in Asian-inspired dishes Translucent, thickens further as it cools forms a “sliceable” gel Sensitive to extended heat exposure, so products become thin if held at heat for long periods of time Table 1 – Common starches and gels used in the bakeshop Starch or GelĪ slurry (mixture of cornstarch and water) is mixed and added to a simmering liquid while whisking until it dissolves and the liquid thickens or Cornstarch mixed with sugar, and cold liquid added Thickened mixture simmered until no starch taste remains See Table 1 for a list of different thickening and binding agents and their characteristics. Starches can be fairly straightforward extracts of plants, such as cornstarch, tapioca, or arrowroot, but there are also modified starches and pre-gelatinized starches available that have specific uses. The more protein structure there is, the chewier the bread. The softness of the crumb of baked bread is due largely to the starch. Starches develop a softer structure when baked than proteins do. Although starches by themselves generally can’t support the shape of the baked items, they do give bulk to the structure. Starch molecules make up the majority of most baked goods, so starch is an important part of the structure. When pasta is cooked in boiling water, the starch in the pasta swells as it absorbs water, and as a result the texture of the pasta softens. Pasta is made mostly of semolina wheat (durum wheat flour), which contains high amounts of starch.Some starches will remain cloudy when cooked others will remain clear. The type of starch determines the final product. The starch will absorb liquid and swell, resulting in the liquid becoming thicker.
In sauces, starches are added to liquids, usually while heating. The most common examples of starch gelatinization are found in sauce and pasta preparations and baked goods. Excessive heating, however, may cause evaporation of the water and shrinkage of the gel. Starch-based gels are thermoirreversible, meaning that they do not melt upon heating (unlike gelatin, which we will discuss later). The result of the reaction is a gel, which is used in sauces, puddings, creams, and other food products, providing a pleasing texture. This gives the system a viscous and transparent texture. As a result, the water is gradually absorbed in an irreversible manner. Starch gelatinization is the process where starch and water are subjected to heat, causing the starch granules to swell.
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