Kvasný průmysl (Oct 2004)
Effect of trub, oxygen content and hopped wort pH on the course of fermentation.
Abstract
The effects of the properties of hopped worts on the course of fermentationand beer character were monitored in this work. Hoppedwort pH in the range of 5,1-5,4 has insignificant effects on the speedof primary fermentation, the breakdown of diacetyl was faster in caseof hopped worts with pH = 5,1 (6,9 days), the slowest diacetyl breakdownwas observed for hopped worts with pH = 5,4 (11,4 days). Fromorganoleptic point of view, finished beers prepared from hopped wortswith a higher pH were preferred.With different wort aeration (8 mg/l, 9 mg/l and 10 mg/l of oxygen),no differences were observed during fermentation. The day of yeastremoval from cylindro-conical fermenters, decrease in diacetyl contentas well as the number of dead yeast cells (to 2 %) were comparable.In case of hopped worts with a higher trub content, 1 day longerbreakdown of vicinal diketones (diacetyl) to the value required,lower foam stability (by 5 s - 2 %) and a lower colloidal stability(approx. by 3 weeks - 9 %) were observed, but no differences inthe organoleptic properties of fresh beers. In case of infusion mashing,a higher haze level at the angle of 90° and a lower haze levelat the angle of 15° were observed in unhopped wort. In hoppedwort, a higher haze level in case of infusion mashing as wellas during decoction mashing at the angle of 90° and 15° was observed.The effects of the properties of hopped worts on the course of fermentationand beer character were monitored in this work. Hoppedwort pH in the range of 5,1-5,4 has insignificant effects on the speedof primary fermentation, the breakdown of diacetyl was faster in caseof hopped worts with pH = 5,1 (6,9 days), the slowest diacetyl breakdownwas observed for hopped worts with pH = 5,4 (11,4 days). Fromorganoleptic point of view, finished beers prepared from hopped wortswith a higher pH were preferred.With different wort aeration (8 mg/l, 9 mg/l and 10 mg/l of oxygen),no differences were observed during fermentation. The day of yeastremoval from cylindro-conical fermenters, decrease in diacetyl contentas well as the number of dead yeast cells (to 2 %) were comparable.In case of hopped worts with a higher trub content, 1 day longerbreakdown of vicinal diketones (diacetyl) to the value required,lower foam stability (by 5 s - 2 %) and a lower colloidal stability(approx. by 3 weeks - 9 %) were observed, but no differences inthe organoleptic properties of fresh beers. In case of infusion mashing,a higher haze level at the angle of 90° and a lower haze levelat the angle of 15° were observed in unhopped wort. In hoppedwort, a higher haze level in case of infusion mashing as wellas during decoction mashing at the angle of 90° and 15° was observed.
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