From grain to malt: Tracking changes of ultra-low-gluten barley storage proteins after malting

Barley (Hordeum vulgare L.) is a major cereal crop produced globally. Hordeins, the major storage proteins in barley, can trigger immune responses leading to celiac disease or symptoms associated with food allergy. Here, proteomics approaches were employed to investigate the proteome level changes of grain and malt from the malting barley cultivar, Sloop, and single-, double- and triple hordein-reduced lines. The triple hordein-reduced line is an ultra-low gluten barley cultivar, Kebari®. Using discovery proteomics, 2,688 and 3,034 proteins in the barley and malt samples were detected respectively. Through the application of targeted proteomics, a significant reduction in the quantity of B-, D-, and γ-hordeins, as well as avenin-like proteins, was observed in the ultra-low gluten malt sample. A compensation mechanism was observed evidenced by increased biosynthesis of seed storage globulins, specifically vicilin-like globulins. Overall, this study has provided insights into protein compositional changes after malting in celiac-friendly barley varieties.