# Impact of Lactic Acid Bacteria on Immunoreactivity of Oat Beers
## 3 Results and Discussion
Electrophoretic separation of proteins was carried out for samples from the subsequent stages of the technological process (grain, malt, sweet wort, hopped wort, bottom- and top-fermented beers) (Figure 4). For unit processes in the production of oat beer, no significant differences were noted in the patterns of immunoreactive protein fractions during the entire process with regular and sour malts. The use of an LAB starter culture did not cause changes in the composition of proteins in malts, worts, and beers. The proteins present in oats showed a high immunoreactivity towards the serum containing antibodies against gliadin. Mainly, these were protein fractions with approximate molecular weights of 35 kDa, 30 kDa, 25 kDa, and 22 kDa. In the course of the  
Figure 4: Identification of proteins involved in the immunoenzymatic reaction. Blots represent regular (A) and sour (B) semi-finished and final products in the oat beer production process, with oats as the control sample. Legend: line 1—molecular weight markers (120 kDa, 85 kDa, 50 kDa, 35 kDa, 25 kDa, and 20 kDa), line 2—oats, line 3—oat regular malt, line 4—wort (regular malt), line 5—hopped wort (regular malt), line 6—top-fermented oat beer (regular malt), line 7—bottom-fermented oat beer (regular malt), line 8—oats, line 9—oat sour malt, line 10—wort (sour malt), line 11—hopped wort (sour malt), line 12—top-fermented oat beer (sour malt), and line 13—bottom-fermented oat beer (sour malt). malting process, some of the proteins were hydrolyzed, as a result of which additional immunoreactive fractions with a molecular weight of 24 kDa and 26 kDa were determined in oat malt, as well as a wide spectrum of proteins with a molecular weight below 10 kDa. Similarly, new immunoreactive fractions were detected in sour malt, identified as 24 kDa and 26 kDa fragments. After the malting process, the protein fraction with a molecular weight of about 25 kDa was no longer present in the malt extract, and it is probable that this fraction was hydrolyzed to low-molecular-weight components. The process of obtaining sweet wort, followed by the filtration stage, resulted in the removal of a significant part of the proteins from the extract. In sweet wort, protein fractions showing an immune response were characterized by molecular weights of 43 kDa, 26 kDa, 23 kDa, and below 10 kDa. According to [PERSON] et al. [24], in oat mashes, the main protein fractions are those with molecular weights of 6-15 kDa, 22 kDa, and 40 kDa. Comparing these data with the results obtained in the study, it can be concluded that all the protein fractions present in oat worts contain epitopes recognized by the antibodies present in the sera used. Boiling wort with hops did not cause significant differences in the composition of immunoreactive proteins present in the wort. In turn, after the fermentation process, no immunoreactive fraction of proteins with the lowest molecular weight (below 10 kDa) was detected in the finished beers. Both bottom- and top-fermented beers achieved similar results. The immune response was mainly triggered by proteins with a molecular weight of about 43 kDa, and a much less intense reaction was observed for the fraction with a mass of 26 kDa. According to [PERSON] et al. [56], in barley, a Z protein weighing about 40 kDa is identified, which is an inhibitor of serine proteinase (so-called serpin). It is present in beer because it is not subject to changes during the beer production process. In oats, the analogue of serpin is a protein with a molecular weight of 43.5 kDa, and it may also be present in beer [24; 58; 59]. An important stage in the research was the in vitro digestion of the obtained beers with proteolytic enzymes (pepsin and pancreatin). The simulated digestion aimed to draw conclusions about possible changes in the immunoreactivity of oat beers occurring after the hydrolysis of beer proteins in the gastrointestinal tract. To activate celiac disease, a gluten peptide must be (partially) resistant to gastrointestinal digestion.