Fundamental study on the impact of transglutaminase on hordein levels in beer

Celiac disease is widespread across the world, with up to 1 in 100 people diagnosed with the disease. Most beers are brewed using barley malt and, hence, are considered unsuitable for individuals suffering from celiac disease or gluten intolerance. In this study, lager beer was produced and treated with different concentrations of microbial transglutaminase (mTG). Quality aspects of each treatment, such as foam and flavor characteristics, were analyzed and showed no significant differences. However, color was significantly affected by mTG treatment. Dynamic light scattering methods were used to analyze particle sizes of samples, which were found to increase significantly when treated with mTG. Western blotting was performed using antigliadin antibodies and showed gluten type proteins to be reduced in samples treated with the highest levels of mTG. The gluten content of the untreated beer was then quantitatively measured using a competitive enzyme-linked immunosorbent assay, giving a result of 88 ppm. Application of mTG at 9.2, 92.5, or 231 g/hL resulted in a significant reduction in gluten content to 45, 12, and 5 ppm, respectively. The beers containing 12 and 5 ppm gluten can be labeled gluten-free by Codex standards.