It seems like no protein is more controversial than gluten. Ask Science explains the science behind this little troublemaker.
It seems like no protein is more controversial than gluten. It shows up in all kinds of diet information, health warnings, at the doctor's office, on food labels. That little protein is everywhere. Let's learn a little more about it..
As you have probably heard if you're at all interested in this protein, gluten is the reason why dough rises. Gluten (whose name comes from the latin word for "sticky"), forms a binding matrix in the dough. This binding matrix traps the carbon dioxide generated by yeast or acid-base reactions, which causes the dough to rise.
Gluten is a protein complex made of two main parts: a glutenin protein and a gliadin protein.
Since scientists love to classify things, we like to group proteins together into "families." Gliadin is a kind of protein called a prolamine. A prolamine is a protein which plants use to store energy and which dissolves in alcohol. Each grain has a different type of prolamine. As we've mentioned, wheat's prolamine is gliadin. Barley uses a prolamine called hordein, and corn uses one called zein.
Glutenin is a kind of protein called a glutelin (if that isn't confusing enough) which can’t be dissolved in alcohol. Each grain also has their own kind of glutelin. However since glutelins don’t dissolve easily, they are more difficult to study and so aren’t well understood. Therefore they have somewhat less-imaginative names. Barley's glutelin is called "barley glutenin," while rye's is called "rye glutenin."
There are many medical conditions that come about as a result of gluten, such as celiac disease, which I'll discuss in a later episode. For many years it was believed that people with celiac disease had an immunological response to the gliadin half of gluten. Recent studies have shown that the glutenin part alone can also trigger the response.
For reasons not yet fully understood, the prolamines in barley, rye, and sorghum also trigger these responses in people with celiac, but those in corn and rice don’t. (The jury is still out on oats).
Keeping Our Glu's Straight
Since the “glu-” in gluten is just a latin root that means “sticky,” some people get a bit confused about which glu- things contain gluten and which don’t. Here are some examples:
Glutenous Rice: Just like all rice, this rice does not contain gluten. The name just means “sticky rice.”
Glutamate: As in monosodium-glutamate (MSG). Glutamate also does not contain gluten. Its name comes from the fact that it comes from glutamic acid.
Glutamic Acid: One of the basic amino acids used to form proteins. Found in just about every food with protein. Does not contain gluten. Gets its name from the fact that it was discovered when someone poured sulfuric acid on gluten back in the 1800s.
Glutamine: Another basic amino acid. Glutamine is made from glutamate by your muscles. It's also found in just about every food with protein. Does not contain gluten.
So now the next time people start taking about gluten, gliadin, and the like, you'll be ahead of the game. In a future episode, I'll take about some of the health issues surrounding this little protein.
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