# Brewing with 10% and 20% Malted Lentils--Trials on Laboratory and Pilot Scales
###### Abstract  
Lentils, a popular foodstuff worldwide, are gaining more interest for their use in alternative diets. In addition, we are observing an ever-growing demand for new raw materials in the malting and brewing industry and an overall rising interest in a low-gluten lifestyle. Therefore, in this study, malt was produced from green lentils and used in both laboratory- and pilot-scale brewing trials. Malted lentils were used as 10% and 20% adjuncts at the laboratory scale, following the Congress mash procedure, and the most important parameters (e.g., filtration time, pH, color, extract, fermentability) of the wort and beer samples were analyzed with a special focus on the concentrations of metal ions (Mg\({}^{2+}\), Ca\({}^{2+}\), Zn\({}^{2+}\), Fe) in wort. The production of beer with lentil malt as an adjunct was then scaled up to 1 hl, and several beer parameters were analyzed, including the gluten content and foam stability. The results showed that the gluten content was decreased by circa 35% and foam stability was enhanced by approximately 6% when adding 20% lentil malt. Furthermore, the use of lentil malt reduced the filtration time by up to 17%. A trained panel evaluated the sensorial qualities of the produced beers. Overall, the use of green lentil malt shows promising results for its potential use in brewing.  
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Compared to other plant kernels, such as cereal grains, legume seeds are usually higher in protein content. The reported protein values for lentils range from 15.9 to 31.4 g/100 g d.m., depending on the variety [16]. Most of the seed protein is stored in the cotyledons, with the majority of the protein content consisting of 70% salt-soluble globulins (storage proteins) that are stored in protein bodies, as well as 16% albumins, 11% glutelins and 3% pro-lamins [26; 27]. Lentils lack a gluten protein fraction, which makes them an attractive food for alternative diets. Currently, there is a rising interest in gluten-free beverages, which contain no more than 20 mg/L gluten according to the World Health Organization [28]. Traditionally, beers are not often gluten-free, as they are made from gluten-containing barley malt [29]. Legumes such as lentils are naturally gluten-free. Therefore, the use of lentil malt as a brewing adjunct to barley malt in the mash bill could be an interesting approach to lower the overall gluten content and produce low-gluten beer.  
Another focus of this research was on the metal ion content in wort. Metal ions play important roles in the brewing process and can either support yeast metabolism (Mg\({}^{2+}\), Ca\({}^{2+}\), Zn\({}^{2+}\)) or negatively affect the overall quality (Fe) of the beer [30; 31; 32; 33].  
In this research manuscript, we propose malted lentils as a new raw material and adjunct in beer production. Our research focused on the production of wort and beer with 10% and 20% addition of malted lentils in both laboratory- and pilot-scale brewing trials. Important standard parameters, as well as the concentrations of Mg\({}^{2+}\), Ca\({}^{2+}\), Zn\({}^{2+}\) and Fe in the resultant wort samples, were analyzed. Finally, a trained panel evaluated the sensorial qualities of the produced beers. Our study is one of the first to evaluate lentil malt as a suitable brewing adjunct and the first to consider lentil malt in the production of gluten-reduced beer.