If you've ever eaten in a cafeteria, chances are good that your dessert options included Jell-O. There are hundreds of different desserts that use Jell-O to create everything from your basic institutional-style gelatin square to ornate designs that incorporate varied Jell-O flavors, fruit, and whipped toppings. Jell-O consists of four basic ingredients:
- sugar or artificial sweetener and artificial flavors
- food coloring
The gelatin in Jell-O is what lets you transform it into all sorts of different shapes. What exactly is gelatin? Gelatin is just a processed version of a structural protein called collagen that is found in many animals, including humans. Collagen actually makes up almost a third of all the protein in the human body. It is a big, fibrous molecule that makes skin, bones, and tendons both strong and somewhat elastic. As you get older, your body makes less collagen, and individual collagen fibers become crosslinked with each other. You might experience this as stiff joints (from less flexible tendons) or wrinkles (from loss of skin elasticity).
The gelatin you eat in Jell-O comes from the collagen in cow or pig bones, hooves, and connective tissues. To make gelatin, manufacturers grind up these various parts and pre-treat them with either a strong acid or a strong base to break down cellular structures and release proteins like collagen. After pre-treatment, the resulting mixture is boiled. During this process, the large collagen protein ends up being partially broken down, and the resulting product is called gelatin. The gelatin is easily extracted because it forms a layer on the surface of the boiling mixture.
Gelatin is a common ingredient in foods because it is so versatile. It can be used as a gelling agent (as in Jell-O), as a thickener, an emulsifier, and a stabilizer. You'll find it in a variety of foods, from yogurt to chewing gum. Here is a list of some other foods that commonly contain gelatin:
- gummy bears
- sour cream
- cream cheese
- cake icing and frosting
- soups, sauces and gravies
- canned ham and chicken
- corned beef
Gelatin is even used to make the coating for pills that makes them easier to swallow. It's also in cosmetics, lozenges, and ointments.
When you buy a box of Jell-O (or another brand of gelatin) at the grocery store, you get a small packet of powdered gelatin with artificial flavorings and colors. At room temperature, the gelatin protein is in the form of a triple helix. This is a fairly ordered structure not unlike that of DNA. With DNA, two chains of nucleotides are twisted together in a spiral pattern. (To learn more about DNA, see How Cells Work. In the gelatin protein, there are three separate chains of amino acids (polypeptide chains) have lined up and twisted around each other, and the helix is held together by weak bonds that form between the amino acids that end up on the inside of the coiled structure.
This gelatin is supposed to taste like an orange. Orange food coloring is added to heighten this sensation.
To make a gelatin mold, you have to add boiling water to the powdered gelatin. You then stir the mixture for about 3 minutes until the gelatin dissolves completely.
Hot water is added to the orange gelatin, and the gelatin mix is stirred until all of the powder has dissolved.
What happens to gelatin when you add boiling water? The energy of the heated water is enough to break up the weak bonds holding the gelatin strands together. The helical structure falls apart, and you are left with free polypeptide chains floating about in solution.
The next step is to add cold water and stick the dissolved gelatin in the refrigerator to chill for several hours. When you cool down the mixture, the polypeptide chains begin to reassociate and reform the tight triple helix structure. However, the chilling process is slow, and the individual strands have been widely dispersed by mixing, so the helices aren't perfectly formed. In some places, there are gaps in the helix, and in others, there is just a tangled web of polypeptide chains. When the gelatin solution is chilled, water is trapped inside these gaps and pockets between chains. The protein net that is left after chilling gives the gelatin mold its shape, and the trapped water provides the characteristic Jell-O jiggle that makes it a popular food for kids to eat.
If you are using a special mold, you need to pour the gelatin mix into the mold before you chill it. The finished product will take on the shape of the container holding it.
Here are some interesting links: