Gelatin (JELL-ah-tin) is a mixture, not a compound. Mixtures
differ from compounds in a number of important ways.
The parts that make up a mixture are not chemically combined
with each other, as they are in a compound. Also,
mixtures have no definite composition, but consist of varying
amounts of the substances from which they are formed.
Gelatin is a mixture of water-soluble proteins with high
molecular weights. It typically occurs as a brittle solid in
the form of colorless or slightly yellow flakes or sheets, or
in powder form, with virtually no taste or odor. It absorbs up
to ten times its own weight when mixed with cold water and
dissolves in hot water. When a solution of gelatin in hot
water is cooled, it takes the form of a gel, a jelly-like material
perhaps most commonly seen as the popular dessert called
JELL-OTM. Gelatin is also available in a number of other
commercial forms, such as Knox GelatinTM, Puragel , and
Gelfoam . Gelatin has been known to humans for many
centuries, but it was not widely marketed until the late
1890s. Its name comes from the Latin word gelatus, which
means ‘‘frozen.’’
Gelatin is made by boiling animal parts with high protein
content, such as skin, ligaments, tendons, cartilage, and
bones. The boiling process breaks down molecular bonds
between individual collagen strands in the animal tissue.
Collagen is a structural protein found in bone, cartilage,
and connective tissue. The collagen formed by this process
can be further disintegrated through additional boiling with
either acid or alkali. Type A gelatin is produced when collagen
is boiled in an acidic solution, and type B gelatin is
produced by boiling collagen in an alkaline solution.
Most of the animal parts used to make gelatin come from
cattle and pigs and are left over from meat and leather
processing. Gelatin can also be made from fish. One of the
oldest forms of gelatin is isinglass, made from the swim
bladders of fish. Jewish and Muslim dietary laws prohibit
believers from eating pork, so some gelatin is made without
pig parts. Vegetarians and vegans do not eat any animal
products, so gelatin manufacturers also make similar products
using vegetable carbohydrates, such as agar and pectin.
These vegetarian gelatins are not true gelatin, which is
always made from animal proteins.
People discovered gelatin centuries ago and experimented
with various uses for it. In the early 1800s, for example,
gelatin was included in the food served to French soldiers as
a source of dietary proteins. In the 1890s, Knox GelatinTM
was sold as a cure for dry fingernails. Manufacturers claimed
that dry fingernails were caused by a lack of protein and that
eating gelatin would cure the condition. No scientific evidence
exists for that claim, but Knox GelatinTM became
popular among consumers nonetheless.
In 1900, the Genesee Pure Food Company began selling
flavored gelatin under the name JELL-OTM. In the early 1900s,
the company began distributing booklets containing recipes
using JELL-OTM, eventually giving out more than 15 million
such booklets. JELL-OTM eventually became one of the most
popular desserts in the United States and other countries. It has
been used to make a variety of pleasant tasting, attractive
looking dessertsmolded intomany different shapes. Cooks have
combined gelatin with water, milk, soft drinks, other liquids,
whipped toppings, or mayonnaise to change its taste and
texture. The product is often served with fruits or vegetables
as a salad. Gelatin is also combined with marshmallows, jellybeans,
jelly, yogurt, gummy candies, ice cream, and margarine
to produce desserts of many textures and flavors. The product is
sometimes recommended as a fat substitute because it provides
volume in a diet without adding many calories. Some people
include gelatin products in their diets as a way of increasing
protein intake. Although plain gelatin is almost entirely
protein, it actually has relatively little nutritional value.
Gelatin has many other uses, including:
• As a raw material for the manufacture of capsules and
gels in the production of drugs;
• As a way of holding silver halide (silver bromide and
silver iodide) crystals in place on photographic films
and plates;
• In the manufacture of blocks used to determine the
possible effects of various types of ammunition on
human flesh;
• As a binder that holds sand on sandpaper or to make
certain types of paper products (such as playing cards)
bright and shiny;
• As an additive in various types of cosmetics and skin
treatments;
• In the manufacture of meshes used in the repair of
wounds and in the production of artificial heart valves;
• In the production of certain types of cement;
• For the manufacture of light filters used in theatrical
productions and for other specialized purposes;
• As a culturing medium for bacteria;
• As a stabilizer and thickener for certain types of foods,
especially ice cream and some other dairy products;
• In the manufacture of printing inks;
• As an additive in the production of plastics and rubber
products.
