Coeliac disease (CD) - suffered by around one per cent of populations worldwide - is exacerbated by the intake of prolamins present in wheat, rye, barley, and (for some people) oats, and the only treatment for CD is a life-long, gluten-free diet.
Moreover, up to 50 per cent of adults remain undiagnosed, or do not display overt symptoms, according to Catassi et al. (1994) and Fowell et al (2006).
The disease causes damage to the small intestinal villi, reducing nutrient absorption and impacting health; clinical symptoms of CD include fatigue, diarrhea, weight loss, anemia and neurological disorders, while research suggests it can heighten cancer risk.
Cograve et al. used mass spectrometric assay (an analytical technique) to characterise hordeins (toxic peptides) originating from hordeum vulgare or the cereal barley, used to produce malt for brewing.
These were present in (1) purified hordein preparations (2) wort (the liquid extracted from the mashing process during beer production) and (3) beer itself - where the current study included tests on 60 commercially available beers.
"There has been some speculation about the presence of and/or amount of gluten present in beers," the scientists wrote.
They added that a recent report examining gluten level in commercial beers found that the gluten content of 50 per cent of beers tested contained less than Codex Alimentarius Standard levels (to be labelled 'gluten free') of 20 ppm (mg/kg) gluten.
But in this study, the scientists found that all barley-based beers contained hordein, and that for beers 57 and 59 (which they did not name) classified as low gluten (<10 ppm), the relative hordein content was not dissimilar to the average hordein content "across the range of beers tested".
Meanwhile, a number of beers tested, despite lacking a defined gluten status, showed lower than average gluten content.
Secondly, Cograve et al. claimed to have developed a "robust and sensitive quantification methodology for the measurement o hordein (gluten) in beer".
In conclusion, no hordeins were detected in gluten-free beers analysed, but discussing the significance of their results, the scientists wrote:
"Significantly, both barley-based low-gluten beers tested, in which the hordein concentration is reduced by proprietary processing steps during brewing (to reduce the concentration in the final beer product) had substantial levels of one or more hordein proteins".
Title: 'What is in a beer? Proteomic characterisation and relative quantification of hordein (gluten) in beer.'
Authors: M.L Cograve, H.goswami, C.A Howitt, G.J Tanner
Source: Journal of Proteome Research, 2011. dx.doi.org/10.1021/pr2008434