Deliciously Gelatinous Chemistry

 

Now that spring has sprung and summer is just over the horizon, a great snack to keep handy during the warm weather months is Jell-O. It jiggles. It’s weird. It’s malleable. And it’s fun, for people of all ages! Jell-O seems to have effectively turned its name from a small trademarked idea in 1897 to a common nomenclature for all modern gelatin snacks. Jell-O’s greatest appeal, besides its taste, is its convenience. It is sold in either powdered form inside of a relatively small cardboard box that can be prepared by just adding water and refrigerating, or in individual Jell-O cups. Maybe that’s why Jell-O is the official state snack food of Utah.

Jell-O is sold in the powdered form of gelatin in little boxes

The secret behind Jell-O is gelatin, a translucent, colorless solid substance. There are many different foods that are made from gelatin, such as gummy bears, all of which just seem to be irresistible  With a little background in gelatin synthesis, the more you will appreciate the strangeness of the compound itself, for how can simple snacks that we take for granted have such a complex chemistry behind it?

As peculiar of a substance as gelatin, it only really is comprised of chemical processes concerning the protein collagen. Hydrolyzed collagen is found exclusively in animal connective tissue, tendons, bones, and skin. This type of collagen, one of 28 identified types, is the collagen used in gelatin. It can’t be found in plants and can only be found in most vertebrates, which is why gelatin is not vegetarian-friendly. The typical amino acid sequences of collagen are glycineproline-X and glycine-X-hydroxyproline, where X is any amino acid other than glycine, proline, or hydroxyproline. These amino acids form polypeptide chains, three to be exact, to form a tropocollagen triple helix known as procollagen, which is a precursor to collagen. The chains are connected by hydrogen bonds, weak bonds between the double bonded oxygen atoms and strong bonds to the adjacent chain’s nitrogens. This process is when hydroxylation occurs, where one molecule of vitamin C is destroyed for each H replaced by OH in the proline, converting them to hydroxyproline. This is necessary to organize the chains to be able to conform in a triple helix.

                              

(left)The three main amino acids that make up collagen triple helixes are glycine, proline, and hydroxyproline. (right) Three polypeptide chains make up collagen, bonded by hydrogen bonds.

The stiff helical structure of collagen molecules then align along the helix axis, bundling together to form what’s called a collagen fibril. Fibrils can further bundle to make the tough micron-sized collagen fibers found in ligaments.

Collagen is synthesized from polypeptide chains of amino acids, in which three chains bond together to form triple helixes, which then bundle to form collagen fibrils.

Collagen doesn’t naturally dissolve in water. In order to make the gelatin, the manufacturers need to grind the body parts of cattle and treat them with a strong acid or strong base in order to dissolve the collagen. The pretreated materials are then boiled, or thermally denatured at temperatures starting at 140°F. Once the temperature reaches 160°F, melting of connective tissue collagen accelerates to dissolve into gelatin. The large collagen protein is partially broken down and results in a gelatin solution. Once the solution is chilled into a jelly-like state, it is dried and ground into a fine powder form. When the gelatin powder is dissolved in hot water, the weak bonds holding the collagen protein chains together are broken. Each chain floats around in the bowl in the form of a triple helix until the gelatin cools and new bonds are formed between amino acids in the protein. Between polymer chains is the colored and flavored water and become trapped as the bonds secure. Jell-O is an amorphous solid.  The reason the Jell-O jiggles when shaken is because although it is mostly water, the liquid is trapped in the protein chains.

Jell-O bounces due to the strong protein chains that trap water.

Gummy bears are another snack other than Jell-O that’s also made of gelatin. 

Jell-O isn’t the only thing made out of gelatin, and if you are vegan, you should stay away from these food products. Things like marshmallows, gummy bears, some yogurts, and skittles all contain gelatin. You could even make things like homemade gummy bears by microwaving and freezing Jell-O for a short period of time. The process of packaging and storing the Jell-O is highly efficient and allows it to be made almost anywhere. The Jell-O brand has accomplished something that few other companies have ever seen. They turned a food product into a household name. With gelatin, we are able to enjoy fun and colorful amorphous solids and call them great summer snacks.

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