The aim of diploma thesis was to investigate the impact of malting conditions on the Congress wort quality. The changing parameters were steeping temperature, lack of aeration during steeping, duration and temperature of germination and duration and temperature of kilning. Congress worts were prepared from pre-malted barley and were evaluated by determining the extract content, the time of starch convertion into sugars, the pH value, the dynamic viscosity, the free amino nitrogen (FAN) content, the total phenol and the total flavonoid content as well as the DPPH• radical scavenging ability. We found a significant effect of steeping, germination and kilning temperatures on the quality of Congress worts. A constant temperature of steeping and germination resulted in lesser accumulation (10␃) or greater losses (20␃) of extract and FAN content in malt, while their combinations (lower T of steeping + higher T of germination or a combination of lower and higher T in time of germination) were found to be better regimes. Higher kilning temperatures resulted in greater losses of extract and FAN, but at the same time increased the content of total phenolic compounds and flavonoids as well as antioxidant activity. A shorter germination time generally led to poorer results, meanwhile we could not directly confirm the positive effect of a longer germination time.
|
