# Impact of Lactic Acid Bacteria on Immunoreactivity of Oat Beers
## 3 Results and Discussion  
In accordance with the main goal of the work, which was aimed at obtaining an oat drink safe for people with gluten intolerance, immunoreactivity tests of raw materials, semi-finished products, as well as the obtained beers were performed. For this purpose, rabbit antibodies directed against peptides rich in proline and glutamine were used, representing the specific sequences appearing in the gluten structure that are considered to be crucial in the pathogenesis of celiac disease. An allergic response could either be induced by the pentapeptide QQQPP or tetrapeptides [27; 48; 49]. The results of enzyme-linked immunosorbent assays performed using rabbit antibodies directed against specific peptide sequences QQQPP, QQQP, and PQQQ are presented in Figure 2. The results obtained for oat raw materials were compared with the results for barley, which is the basic brewing raw material. The immune response was expressed as a percentage of the immunoreactivity of wheat. The mean values of the immune response of barley grains determined with rabbit antibodies against PQQQ and QQQP were approximately 76% and 64%, respectively. The mean immunoreactivity values of oats obtained with the use of these antibodies were several times lower than those for barley and reached only 20%. A much higher value was determined using the QQQPP pentapeptide. The pentapeptide QQQPP is considered to be the most toxic to people suffering from celiac disease, and it is also the most active allergen among the low-molecular-weight fraction of wheat proteins [27; 50]. In the conducted research, the mean value of immunoreactivity of oats, determined with the use of antibodies directed against the QQQPP pentapeptide, was as high as 62%. Such a strong immune response, with a simultaneous large standard deviation of the results, indicating the heterogeneity of the samples, suggests with a high probability that the raw material used was contaminated with gluten cereal grains. Similar observations were made by [PERSON] and [PERSON] [51], who drew attention to the risk of oat cross-contamination with gluten-containing grains and, at the same time, the large differences in the adverse response to gluten exposure among CD patients. However, the remaining immunoreactivity of oats assessed for the examined samples was still much lower than the value determined for wheat gluten (100%) or for barley, which showed an immune response of 83%. Similarly, the mean values of the remaining immunoreactivity for the PQQQ and QQQP sequences were much lower in oat malls than in barley malt and did not exceed 26%, with values for barley malt of 76% and 66%, respectively. In the case of anti-QQQPP peptide antibodies, the differences were not so pronounced due to the high heterogeneity of the  
Figure 2: Immunoreactivity of brewery raw materials determined with rabbit antibodies. X\({}_{\text{mean}}\)\(\pm\) SD, n = 6. Asterisks (\({}^{\circ}\)) indicate a statistically significant difference (\(p<0.05\)) compared to the barley counterpart. oat malt samples. Unlike [PERSON] et al. [52], who noted an increase in immunoreactivity after the malting process for barley malts, in this study, for both cereal species, the malting process did not cause a statistically significant (\(p<0.05\)) increase in the immune response. Although the germination process may result in the exposure of specific epitopes involved in the immunological reaction as a result of proteolytic hydrolysis of the proteins contained in the grain, at the same time, the products of further hydrolysis formed in the course of the technological process may lose their allergenic properties. In the germination process, not only are the proteolytic enzymes present in the grain activated, but an additional pool of newly synthesized enzymes is created [46; 53; 54]. Thus, the final result depends on the activity of all the proteases involved in malting.