Proteases effectively hydrolyze proteins into smaller molecules of peptides, even down to amino acid units, which can be assim- ilated by brewer’s yeast during fermentation [14]. In the present study, FAN level profiles for fermenting worts are shown in Fig. 1. The FAN level decreased dramatically in the first 4 days for 20 ◦ P worts fermentation (decreased by ca. 100 mg/L) because of the yeast fast consumption in the early stages of fermentation. With increase in the gravity from 20 ◦ P to 24 ◦ P, the same trend was observed in the first 6 days (decreased by ca. 80 mg/L). The prolonged time and the lower amount of consumed FAN with increased wort gravity are due to the fact that higher wort gravity increases external osmotic pressure resulting in a deterioration of viability and growth of brewer’s yeast [15]. Afterwards, the FAN level remained constant for the control worts in both 20 ◦ P (ca. 140 mg/L) and 24 ◦ P (ca. 240 mg/L) till the end of fermentation. It has been reported significant FAN consumption occurred during