The object of this study was to assess how the Malt substitution with maize products and several preparing methods influence the content of free amino nitrogen and total souble nitrogen in laboratory worts. The raw materials for this study were barley malt and several granulated com products: maize grits (500-1250 μm) and fine maize grits (250-500 μm and 250-750 μm). The unmalted raw material was submitted to gelatinization. Com products were mixed with water in proportion 1:5 and gelatinized at 90°C for 10 min. and than cooled to 45°C. The adjuncts were differently treated: (1) without enzymes, (2) with 5% adding of malt and (3) with 10% adding of malt as natural source of enzymes. Native maize prepared by above methods was added in proportions 10, 20, 30 and 40%. Mashing at 45°C was started immediately after gelatinization process. Experiments were carried out on a laboratory scale by using an infusion mashing procedure for wort production. In this way obtained worts, free amino nitrogen by ninhydryn method and total souble nitrogen by Kjeldhal method. Larger were determined than 20% amounts of maize decreased content of souble nitrogen and free amino nitrogen what was insufficient for proper yeast metabolism.
malt, cereal adjuncts, maize, free amino nitrogen, total souble nitrogen