# Impact of Lactic Acid Bacteria on Immunoreactivity of Oat Beers
## 1 Introduction  
In people with celiac disease, the consumption of gluten-containing products triggers an immune response in the small intestine, which is associated with impaired absorption of nutrients from food. Celiac disease, as well as other forms of gluten intolerance, is not curable and requires a lifelong gluten-free diet, i.e., exclusion of gluten cereals from the menu [1; 2; 3]. A gluten-free diet is often deficient in nutrients, so the possibility of broadening the range of permitted products with alternative ingredients is constantly sought [4; 5; 6]. Recent research has shown that oats can be tolerated by the majority of people who suffer from celiac disease [2; 7; 8]. Oats, unlike wheat, rye, and barley, do not cause symptoms of the disease in most people suffering from celiac disease as there is a significant difference in the chemical composition between oats and gluten cereals [9; 10]. The results of numerousclinical studies, which demonstrated the possibility of the safe consumption of oat products by people with celiac disease, resulted in the acceptance of oats as a foodstuff suitable for a gluten-free diet in Europe (2009, Commission Regulation (EC), No. 41/2009) and the USA (2013, FDA regulation) [11; 12; 13]. Moderate consumption of oats by people with celiac disease is beneficial due to their high nutritional value and health-promoting effects, resulting mainly from their high content of dietary fiber and protein rich in essential amino acids [14]. Oat \(\beta\)-glucan, due to its prebiotic properties, stimulates the growth of lactic acid bacteria in the intestines [8]. Consumption of \(\beta\)-glucans from oats helps to limit the increase in blood glucose levels after a meal and helps to maintain normal blood cholesterol levels [14; 15; 16]. However, there are cases where after eating oat products, symptoms of intolerance appear, which are associated with contamination of oat products with wheat, rye, and barley [17; 18; 19]. Numerous studies have shown that products labeled gluten-free, and even more often those naturally gluten-free, may be contaminated [20; 21]. The reason for the presence of prolamins of other cereals in oat products is that oats are grown near wheat or barley, which creates the possibility of cross-contamination, and, in addition, the same machines are used to harvest and transport different cereals. Grain is also contaminated during storage and processing at food industry plants [9; 19; 22]. One of the possibilities of using oat grain in a gluten-free diet is to use it as a raw material for beer production. Maling and lactic acid fermentation are considered very effective in enhancing the functionality of cereal grains [23]. Even though oats are not a conventional raw material for brewing, they have great potential for creating new types of beer that are safe for celiacs [24; 25; 26]. However, in attempts to produce oat beer, the potential contamination of oat grains with gluten cereals during the processing stage is a real risk, as it is difficult to avoid in large-scale production. Proline- and glutamine-rich gluten proteins responsible for evoking celiac disease are among the major constituents of cereal dietary proteins, which are largely resistant to complete cleavage by the human gastrointestinal tract's digestive enzymes [27; 28]. These digestion-resistant amino acid sequences, consisting mainly of proline and glutamine, cause adverse reactions of varying severity in gluten-intolerant individuals [29; 30]. Various strategies are currently being used to find solutions for people with gluten hypersensitivity. The basic recommendation is to follow a restrictive diet consisting of certified products that are naturally gluten-free, which, however, as mentioned, does not always provide a 100% guarantee of safety due to potential contamination. In addition, new products are developed by purifying gluten-containing raw materials via enzymatic treatment.