There are four gluten-like protein families in barley, called hordeins, and a number of lines of barley are deficient in genes or have reduced protein production of one or more of these protein families.
Exploiting this knowledge, the researchers combined a line of barley that didn’t produce one form of hordein with another line deficient in a different form of hordein and were able to produce a line that did not contain either protein family.
After stabilising the line by allowing it reproduce by single seed for a number of generations and confirming the mutation didn’t reverse, they crossed this new line of barley with a third line that didn’t contain a third family of hordein. The line was stabilised and the gluten content assessed.
Using two methods to detect hordeins in the new line (ELISA and Mass Spectrometry), reductions in each family of gluten protein was confirmed. The gluten content was below 20 parts per million, the limit for a food to be considered gluten-free.
The researchers noted that the seeds produced by the new line looked shrunken but by growing in a different climate this trait, which may affect agronomic desirability and saleability, was correct reasonably well.
But the most important test, or at least reasonably important given where the scientists were located, was whether the new barley could be used to brew some decent beer – and it can! Although the barley suffered from slower filtration and required an increase in the malt load, there was no impact on starch conversion and the researchers concluded that some small scale brewing and subsequent taste testing showed it was possible to create a half decent brew.
With approximately 1% of most populations diagnosed with Coeliac disease and up to 10% gluten sensitive amongst some populations, such advances could be important in overcoming resultant adverse health effects such as low bone mineral density and increased intestinal malignancy.
However, as the researchers note early on in their article, barley doesn’t form a large part of most diets. Further, the method used in this research is not easily transferred to, for example, bread wheat. The gene structure and number of genes involved in producing gluten proteins in bread wheat is considerably more complex than that in barley.
But it is an impressive proof of concept that may improve the health of effected people.