# Brewing with 10% and 20% Malted Lentils--Trials on Laboratory and Pilot Scales
## Results and Discussion
### Laboratory-Scale Brewing Trial
#### 3.1.9 Metal Ion Analyses  
The concentrations of the measured metal ions (Mg\({}^{2+}\), Ca\({}^{2+}\), Zn\({}^{2+}\), Fe) were similar in all wort samples (Table 3). The only exception was a slightly higher zinc content of 0.56 \(\pm\) 0.05 mg/L for Congress wort produced with 20% lentil malt. Most of the metal ions that occur naturally in seeds are removed by the malting process and then further depleted during the different steps of the brewing process, especially with the spent grains after lautering [50,51]. The variety of the cereal or legume also has an impact on metal content. [PERSON] and [PERSON] [52] showed that different varieties of lentils can differ in their metal ion content. The measured metal ion contents were all attributable to the malts used, as distilled water was used in accordance with the Congress mask procedure. This is also closer to industrial standards, where treated soft water with low mineral content is typical. In the literature, Mg\({}^{2+}\) levels of 40-100 mg/L have been reported in all-barley malt wort [46]. The Mg\({}^{2+}\) levels measured in Congress worst samples were in this range, with values of 77.9 \(\pm\) 4.1 (BM), 71.9 \(\pm\) 8.2 (BM + 10% LM) and 78.1 \(\pm\) 5.5 mg/L (BM + 20% LM). Similar values were reported by [PERSON] et al. [32]. The Mg\({}^{2+}\) concentration influences phosphorylation and cannot be exchanged with another mineral. Additionally, it works as a coenzyme for carboxy- and decarboxylases [53]. The Ca\({}^{2+}\) ion concentrations in the Congress worst samples were 21.3 \(\pm\) 4.1 (BM), 21.7 \(\pm\) 1.6 (BM + 10% LM) and 23.2 \(\pm\) 5.5 mg/L (BM + 20% LM), which are within the desired range of 10-60 mg/L [46]. Calcium ions stimulate yeast multiplication and affect enzymatic activities and yeast flocculation [54]. On the other hand, excessive levels of Ca\({}^{2+}\) are undesirable due to their potential reaction with oxalic acid. This reaction forms calcium oxalate which is known to promote gushing [47]. The Zn\({}^{2+}\) concentration in the Congress worst samples were 0.43 \(\pm\) 0.07 (BM), 0.48 \(\pm\) 0.1 (BM + 10% LM) and 0.56 \(\pm\) 0.05 mg/L (BM + 20% LM). The literature reports several suitable zinc levels ranging from 0.05 to 0.25 mg/L [46,47,55,56]. However, higher concentrations (up to 0.9 mg/L) have been reported [30]. Zinc levels have important physiological effects, as Zn\({}^{2+}\) is involved in protein synthesis, the multiplication of yeast cells and fermentation. Zn\({}^{2+}\) ions are actively translocated into the yeast cell to carry out important physiological roles and are mostly retained in the cell [57]. A lack of zinc (less than 0.1 mg/L), can lead to poor multiplication of yeast cells, slow fermentation and the partial reduction of diacetyl [47]. The Zn\({}^{2+}\) contents of the Congress worst samples were measured before boiling and without the addition of hops. Therefore, hot truly was not formed and separated from the wort before pitching. As large amounts of Zn\({}^{2+}\) ions are removed with the hot trub, the slightly higher measured zinc contents by the omission of this step [50,58]. Pitching wort zinc concentrations that are higher than 0.6 mg/L can lead to yeast autolysis and a subhury off-flavor [47]. However, the need for zinc depends on the yeast strain used [53]. Wort with the addition of 20% lentil malt showed significantly higher zinc content compared to all-barley malt Congress wort and the wort with 10% malted lentils. Therefore, lentil malt could be used as a supplementary zinc source when brewing with raw materials that have low zinc content. The iron ion contents of the Congress wort samples were 0.11 \(\pm\) 0.05 (BM), 0.13 \(\pm\) 0.06 (BM + 10% LM) and 0.16 \(\pm\) 0.07 mg/L (BM + 20% LM), which all fall within the required range of 0.10-0.27 mg/L [47,55,59]. In the brewing process, most iron is removed with the spent grains after filtration [30,60].