A close inspection of the nutrition label on most processed foods will usually turn up—among other disturbingly-named ingredients whose function is unclear—something known as “hydrolyzed soy protein” or “hydrolyzed wheat protein”.
What is it, and why is it added to so many processed food products?
What Is Protein, Anyway?
“Protein” is a generic term for an animal or plant tissue made out of individual proteins. These individual “proteins” are just long chains of amino acids linked together, end to end.
There are 20 amino acids in our genetic code, each an individual molecule with its own shape—and the sequence of amino acids in a protein determines its three-dimensional shape. Our cells can build anything from collagen to digestive enzymes out of the correct sequence of amino acids!
A short protein is called a “peptide”, but there’s no set number of amino acids under which the term is used. Calling a protein a “peptide” is like calling a person “short”: it’s a relative judgment.
Why Is There So Much “Hydrolyzed Vegetable Protein”?
Now that we know proteins are just strings of amino acids, we can understand what “hydrolyzed vegetable protein” is.
Note that it’s no longer legal to use the term “hydrolyzed vegetable protein” on a nutrition label in the USA: the source of the protein must be listed, e.g. “hydrolyzed soy protein”, “hydrolyzed wheat protein”. (Source: USDA Flavorings FAQ.)
The process of extracting seed oils from soybeans or corn (a disturbing series of chemical reactions involving hexane, taking place in chemical plants that look a lot like oil refineries) leaves behind dehulled, defatted soy or corn meal. Typically this mush is fed to cattle…but since it’s cheap and produced by the ton due to massive, destructive subsidies for industrial monocrop agriculture, there is great financial incentive to figure out how to feed it to humans.
Wheat protein is simpler to produce: since gluten (the collective name for wheat proteins, including both glutelins and gliadins) doesn’t dissolve in water, wheat flour is simply washed with water to dissolve away the starch. (How it’s done, featuring lots of delicious phrases like “homogenized slurry”.)
As one might expect from the name “gluten”, the result is…gluey. (This is what gives bread it’s stretchiness.) As anyone who’s ever used nutritional yeast by mistake, instead of baking yeast, can attest, the result is a heavy, indigestible solid with the approximate density of a brick and the consistency of hardened wood glue. And wheat flour dissolved in water makes an excellent adhesive for putting up posters…or even wallpaper.
This lack of digestibility is among the many reasons why wheat protein, in addition to all its disruptive effects on intestinal function, is the lowest-quality protein commonly available. (Other reasons include a deficiency of the essential amino acids lysine and methionine.) Whole wheat protein scores only 0.25-0.42 on the PDCAAS, with beef protein at 0.92, and eggs and milk at 1.0. Corn protein isn’t any better: it scores between 0.22 and 0.46. (Even soy scores a 1.0 on the PDCAAS—though soy products cause other issues I don’t have space to discuss here.)
Therefore, fake vegetarian meat substitutes like seitan, veggieburgers, and Tofurky—which usually use gluten to help simulate the texture of meat—are using the most biologically disruptive and lowest-quality protein available.
What Is “Hydrolyzed Vegetable Protein”?
The protein we’ve extracted can be spray-dried into “textured vegetable protein”, which would require another article to explain…
…or the protein can be “hydrolyzed”. Hydrolysis is basically chemical digestion on an industrial scale: the protein is dropped into a vat of sulfuric acid, boiled for several hours to over a day in order to break down the proteins, after which lye is added to raise the pH back to neutral. (Yum!)
I’ve been asked “If our stomachs can digest protein in a few hours, how come it has to be boiled in sulfuric acid for up to a day?”
Answer: our stomach isn’t just an acid vat. Both our stomach and our intestines contain proteolytic enzymes, like pepsin and trypsin—chemicals specifically tuned to break down bonds between amino acids. However, when hydrolyzing protein on an industrial scale, sulfuric acid and heat is generally cheaper than enzymes.
The longer a protein is hydrolyzed, the more that big, long, gluey proteins (like wheat gluten) will be broken down into shorter proteins—or even into individual amino acids.
Why Is Protein Hydrolyzed, and Why Is Hydrolyzed Protein In So Much Of Our Food?
If you’re thinking this all seems like a lot of work for not much benefit, you’re not alone. Hydrolyzed protein usually shows up near the end of the ingredient list: why would food companies go to so much trouble just to add a tiny bit of protein to their food?
The answer is simple: when we hydrolyze a protein down to free amino acids, one of the amino acids we get is glutamic acid, known as glutamate in its anionic form. And since wheat gluten in particular contains a lot of glutamine, hydrolyzed wheat protein will contain a lot of free glutamate.
For more than you probably wanted to know about glutamate vs. glutamine and their metabolism, try these articles and papers:
Glutamine: The Essential “Non-Essential” Amino Acid
Ivy Greenwell, LE Magazine, September 1999
J. Nutr. April 1, 2000 vol. 130 no. 4 978S-982S
Intestinal Glutamate Metabolism
Peter J. Reeds, Douglas G. Burrin, Barbara Stoll and Farook Jahoor
And free glutamate is the molecule that plugs into the taste receptor we call “umami”…
…the same taste receptor that’s tickled by the abundant free glutamate in soy sauce, Parmesan and Roquefort cheese, Vegemite and Marmite, fish sauce, nori, kombu, and MSG.
Glutamine And Glutamate Are Not Gluten…But “Hydrolyzed Wheat Protein” Can Still Be Gluten
It’s easy to get confused due to the similar names, so I’ll restate the point: glutamine (and glutamate, its carboxylate anion) is not the same as gluten!
Gluten is the collective term for the proteins found in wheat and other gluten grains, like barley, rye, and triticale. Glutamine and glutamate are forms of a single amino acid. They’re found in almost every protein in the world, and they can’t cause a celiac or allergic reaction by themselves.
However, “hydrolyzed wheat protein” can still contain the peptides which affect zonulin signaling and cause problems for celiacs and the allergic…it all depends on the degree of hydrolysis. I wouldn’t risk it myself.
(Note that another name for “hydrolyzed wheat protein” is “glutamine peptides”, often found in sports nutrition products like whey protein. Beware!)
What Is “Umami?”
The easiest way to explain “umami” is “that yummy taste that’s in all the condiments I just listed”, usually described as “savory” or “meaty”. But why would humans have a taste sensor for free glutamate?
The answer becomes clearer when we realize that all the foods in the above list are heavily processed products of agricultural civilization. if we look down the list of free glutamate-containing foods until we find non-processed foods available to Paleolithic humans, we find shellfish (100-200), meat, fish, and milk (20-70).
In other words, we find sources of good, complete protein. So it’s clear that our taste sensors for “umami” evolved to sense protein…
…that we’ve discovered how to trick our protein sensor by creating lots of free glutamate out of things like seaweed and hard cheese…
…and, most recently, hydrolyzed soy, corn and wheat protein.
You’ll note that many other popular neolithic foods contain free glutamate far in excess of their protein content…which, I suspect, is one reason we enjoy their taste. Peas, corn, tomatoes, potatoes, grape juice, and cured ham contain far more free glutamate than meat or shellfish…and green tea contains almost as much glutamate as soy sauce! (Table, again.)
- “Hydrolyzed vegetable protein” is a flavor enhancer…
- …because it stimulates our umami taste receptors, just like soy sauce, Parmesan cheese, or MSG.
- However, it’s much cheaper than real food, because the USA heavily subsidizes the production of corn, soy, and wheat…
- …and, in the case of soy and corn, it’s made from a byproduct of soy and corn oil manufacturing that would otherwise be fed to cattle.
And that’s why we find “hydrolyzed wheat protein” and “hydrolyzed soy protein” in so many processed “foods”.
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