# Impact of Lactic Acid Bacteria on Immunoreactivity of Oat Beers
## 3 Results and Discussion
Although it was expected that the use of a starter culture with steeping water would result in a weakening of the immune response already at the malt production stage due to potential proline endopeptidase activity typical of LAB, the immunoreactivity level of oat sour malt was not significantly lower (\(p>0.05\)) than that of regular malt. The strain used in the study originated from sour grain mash, and this choice was based on its suitability for optimizing the technological parameters of oat malt. Its ability to hydrolyze toxic gluten sequences was not effective enough to demonstrate a significant impact on the immune response at this stage of oat processing. As indicated by numerous studies [31], a broad set of enzymes is necessary for the complete degradation of immunoreactive peptides, which can only be achieved by the simultaneous use of several LAB strains. In the further part of the study, changes in the level of remaining immunoreactivity in subsequent stages of the oat beer production process were examined. The findings showed that immunoreactivity was effectively reduced in the course of the beer production process, during which most of the toxic protein fractions were removed (Figure 3). The mashing process contributes most to the reduction in immunoreactivity. In the mashing process, during the proteolytic rest, malt proteins are hydrolyzed into soluble proteins due to the action of endogenous proteolytic enzymes. Most of them are then converted into free amino nitrogen (FAN). A gradual increase in temperature in the later stages of mashing causes further reduction of protein content due to physical factors such as precipitation and adsorption [32; 33]. In the post-mashing filtration process, most of the proteins are removed from the beer along with the sediments, and only simple polypeptides  
Figure 3: Immunoreactivity of oat sour malt, obtained words, and beers determined with rabbit antibodies. X\({}_{\text{mean }}\pm\) SD, n = 6. Asterisks (*) indicate a statistically significant difference (\(p<0.05\)) in comparison with the previous production step. pass into the word [55; 56]. This was reflected in a sharp decrease in the immune response determined for sweet wort, which ranged from 2.3% to 3.6% depending on the rabbit antibodies used for testing. In addition, at this stage, the highest values were found for the reaction with the QQQPP pentapeptide. However, some proteins with a strong allergenic nature can still enter beer during the technological process and cause allergic reactions in hypersensitive people [57]. Further reduction of the immune response occurred after boiling the wort with hops and the separation of truly. The fermentation and maturation process of beer also had a positive effect on the weakening of the immunoreactivity of the product. This was the result of the precipitation of certain proteins as a result of the decrease in pH and the adsorption of these compounds onto yeast cells [52; 56]. In addition, the beer obtained in this study was filtered using diatomaceous earth after fermentation, which resulted in the removal of another portion of proteins. In the finished oat beers, the immune response was only 1.5% to 1.9% in comparison to wheat flour. The results of the study justify the statement that the process of mashing and filtration, as well as fermentation and stabilization of beer, has a statistically significant impact (\(p<0.05\)) on the gradual decrease in the immunoreactivity of the tested oat drinks. However, even in the final beverages, no significant differences were found between the types of malt used (regular vs. sour malts) (\(p>0.05\)) or the types of fermentation (bottom- vs. top-fermented beers) (\(p>0.05\)). To more deeply investigate changes in the immunoreactivity of the samples during the oat beer production process, an immunoblotting technique was used to identify proteins involved in the immunoenzymatic reaction with antibodies from celiac disease sufferers.