Main ingredients gelatin
|Serving temperature Chilled|
|Similar Dessert, Pudding, fruit preserves, Fruit, Mousse|
They can be made by combining plain gelatin with other ingredients or by using a premixed blend of gelatin with additives. Fully prepared gelatin desserts are sold in a variety of forms, ranging from large decorative shapes to individual serving cups.
Before gelatin became widely available as a commercial product, the most typical gelatin dessert was "calf's foot jelly". As the name indicates, this was made by extracting and purifying gelatin from the foot of a calf. This gelatin was used for savory dishes in aspic, or was mixed with fruit juice and sugar for a dessert.
In the eighteenth century, gelatin from calf's feet, isinglass and hartshorn was colored blue with violet juice, yellow with saffron, red with cochineal and green with spinach and allowed to set in layers in small, narrow glasses. It was flavored with sugar, lemon juice and mixed spices. This preparation was called jelly; Hannah Glasse was the first to record the use of this jelly in trifle in her book The Art of Cookery, first published in 1747.
To make a gelatin dessert, gelatin is dissolved in hot liquid with the desired flavors and other additives. These latter ingredients usually include sugar, fruit juice, or sugar substitutes; they may be added and varied during preparation, or pre-mixed with the gelatin in a commercial product which merely requires the addition of hot water.
In addition to sweeteners, the prepared commercial blends generally contain flavoring agents and other additives, such as adipic acid, fumaric acid, sodium citrate, and artificial flavorings and food colors. Because the collagen is processed extensively, the final product is not categorized as a meat or animal product by the US federal government.
Prepared commercial blends may be sold as a powder or as a concentrated gelatinous block, divided into small squares. Either type is mixed with sufficient hot water to completely dissolve it, and then mixed with enough cold water to make the volume of liquid specified on the packet.
The solubility of powdered gelatin can be enhanced by sprinkling it into the liquid several minutes before heating, "blooming" the individual granules. The fully dissolved mixture is then refrigerated, slowly forming a colloidal gel as it cools.
Gelatin desserts may be enhanced in many ways, such as using decorative molds, creating multicolored layers by adding a new layer of slightly cooled liquid over the previously-solidified one, or suspending non-soluble edible elements such as marshmallows or fruit. Some types of fresh fruit and their unprocessed juices are incompatible with gelatin desserts; see the Chemistry section below.
When fully chilled, the most common ratios of gelatin to liquid (as instructed on commercial packaging) usually result in a custard-like texture which can retain detailed shapes when cold but melts back to a viscous liquid when warm. A recipe calling for the addition of additional gelatin to regular jelly gives a rubbery product that can be cut into shapes with cookie cutters and eaten with fingers (called "Knox Blox" by the Knox company, makers of unflavored gelatin). Higher gelatin ratios can be used to increase the stability of the gel, culminating in gummy candies which remain rubbery solids at room temperature (see Bloom (test)).
The Bloom Strength of a gelatin mixture is the measure of how strong it is. It is defined by the force in grams required to press a 12.5 mm diameter plunger 4 mm into 112 g of a standard 6.67% w/v gelatin gel at 10 °C. The Bloom Strength of a gel is useful to know when determining the possibility of substituting a gelatin of one Bloom Strength for a gelatin of another. One can use the following equation:
C x B½ = k
or C1(B1)½÷(B2)½ = C2
Where C = concentration, B = Bloom strength and k = constant. For example, when making gummies, it's important to know that a 250 Bloom gelatin has a much shorter (more thick) texture than a 180 Bloom gelatin.
A gelatin shot (usually called a Jell-O shot in North America and vodka jelly or jelly shot in the UK and Australia) is a shooter in which liquor, usually vodka, rum, tequila, or neutral grain spirit, replaces some of the water or fruit juice that is used to congeal the gel.
The American satirist and mathematician Tom Lehrer claims to have invented the gelatin shot in the 1950s while working for the National Security Agency, where he developed vodka gelatin as a way to circumvent a restriction of alcoholic beverages on base. An early published recipe for an alcoholic gelatin drink dates from 1862, found in How to Mix Drinks, or The Bon Vivant's Companion by Jerry Thomas: his recipe for "Punch Jelly" calls for the addition of isinglass or other gelatin to a punch made from cognac, rum, and lemon juice.
Other culinary gelling agents can be used instead of animal-derived gelatin. These plant-derived substances are more similar to pectin and other gelling plant carbohydrates than to gelatin proteins; their physical properties are slightly different, creating different constraints for the preparation and storage conditions. These other gelling agents may also be preferred for certain traditional cuisines or dietary restrictions.
Agar, a product made from red algae, is the traditional gelling agent in many Asian desserts. Agar is a popular gelatin substitute in quick jelly powder mix and prepared dessert gels that can be stored at room temperature. Compared to gelatin, agar preparations require a higher dissolving temperature, but the resulting gels congeal more quickly and remain solid at higher temperatures, 104 °F (40 °C), as opposed to 59 °F (15 °C) for gelatin. Vegans and vegetarians can use agar to replace animal-derived gelatin.
Konjac is a gelling agent used in many Asian foods, including the popular konnyaku fruit jelly candies.
Gelatin consists of partially hydrolyzed collagen, a protein which is highly abundant in animal tissues such as bone and skin. Collagen is a protein made up of three strands of polypeptide chains that form in a helical structure. To make a gelatin dessert, such as Jello, the collagen is mixed with water and heated, disrupting the bonds that hold the three strands of polypeptides together. As the gelatin cools, these bonds try to reform in the same structure as before, but now with small bubbles of liquid in between. This gives gelatin its semisolid, gel-like texture.
Because gelatin is a protein that contains both acid and base amino groups, it acts as an amphoteric molecule, displaying both acidic and basic properties. This allows it to react with different compounds, such as sugars and other food additives. These interactions give gelatin a versatile nature in the roles that it plays in different foods. It can stabilize foams in foods such as marshmallows, it can help maintain small ice crystals in ice cream, and it can even serve as an emulsifier for foods like toffee and margarine.
Although many gelatin desserts incorporate fruit, some fresh fruits contain proteolytic enzymes; these enzymes cut the gelatin molecule into peptides (protein fragments) too small to form a firm gel. The use of such fresh fruits in a gelatin recipe results in a dessert that never "sets".
Specifically, pineapple contains the protease (protein cutting enzyme) bromelain, kiwi fruit contains actinidin, figs contain ficain, and papaya contains papain. Cooking or canning denatures and deactivates the proteases, so canned pineapple, for example, works fine in a gelatin dessert.
Although eating tainted beef can lead to New Variant Creutzfeldt–Jakob disease (the human variant of mad-cow disease, bovine spongiform encephalopathy), there is no known case of BSE having been transmitted through collagen products such as gelatin.
In many of the Commonwealth nations including Canada and in Ireland, gelatin desserts are called jelly. In the United States, gelatin desserts are sometimes called jello or gelatin, whereas jelly is a fruit preserve.