Understanding Gluten: An Umbrella Term

UNDERSTANDING Glutens

What is the difference, you might ask, of gluten in these three grains? Isn’t the Gluten Protein in wheat, barley and rye? The short answer is yes, which is why they don’t work for folks with Celiac disease. But did you know that there is no “Gluten Protein” per se? In understanding Gluten, it is important to know that Gluten is an umbrella term for three(3) separate and distinct Gluten Protein Types in each of these grains. For Wheat, it is Gliadin, for Barley it is Hordein, and for Rye it is Secalin.

This can make it appear as though identifying gluten or any protein is simple; the above just has 3 proteins to test for, right? Not exactly. Not at all, really. Three main reasons  to highlight for our purposes:

1. Within each of these protein types, there are many proteins:
   • E.g. Gliadin has ω5-gliadins, ω1,2-gliadins, α-gliadins, γ-gliadin, etc.
2. These are not the only proteins in grains. There are both Gluten and Non-Gluten Protein types
3. Each of the Gluten and Non-Gluten Protein types have many proteins and protein fractions.

Table   1^[1] summarizes data that reflect the 3 points above and illustrates the shear numbers of proteins involved when we use the word “Gluten”, known as storage proteins, and “non-gluten” proteins.

Table 1 T.B Osborne developed this framework, which uses solubility as the basis for classification.

Often for those who have allergies, which is different from Intolerance, the offending allergen may be non-gluten proteins. So isolating the fraction to which they react for testing purposes can be difficult.

There is a significant body of work in the scientific community on this topic over the past few decades.  There are challenges many areas of accurately quantifying gluten content. Just isolating the set of proteins in a repeatable way is the subject of many of the studies.  There are challenges in what equipment is suitable, what methods and reference material are suitable….And most salient to our discussion: what antibody is suitable.

The intent of this post is to demystify some the the super-scientifc content out there, so I won’t include excerpts from the scientific sources, but if you are a super nerd, you could check out this publication: Isolation and characterization of gluten protein types. It is an older article, which points to how long this topic has been studied.

So what about beer?

It ends up, fermentation introduces even more complexities, which further complicates measurement ^[2], so the antibody used in the test is important. When considering hard-to-measure substances in gluten testing, the usual suspects emerge: soy sauce, sourdough bread and beer.

There are many testing kits on the market for testing the Gluten content of foods. They key to testing Beer is identifying and using a kit with the right antibody. Look out for future posts on the kits and on which antibodies are best for beer.

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[1] Table data from “Cereals: Rationale for Fermentation” Professor Norman F. Haard, University of California, Institute of Marine. Resources: Department of Food Science and Technology, Davis, California 95616, USA. Table Data references: Eliasson and Larsson (1993); Alais and Linden (1991)

[2]
010 Jan-Feb;93(1):190-6 Recognition of gliadin and glutenin fractions in four commercial gluten assays. Allred LK, Ritter BW.
Author information:
ELISA Technologies, Inc., 2501 NW 66th Ct, Gainesville, FL 32653, USA. laura.allred@elisa-tek.com