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Pilot trials on the influence of the various mash parameters on the properties of wort and beer with particular respect to flavour stability
Narzi, L., Back, W., Miedaner, H., and Takahashi, Y.

Various mash-parameters have been investigated with respect to the beer properties flavour/taste and flavour stability. The test brews took place in the scales of 60, 9 and 220 litres. Worts and beers were analysed according to conventional methods as well as by three different methods of multidimensional gaschromatography and mass spectrometry. The organoleptic evaluation was achieved by the DLG-test and a special "ageing test". The addition of nitrogen-gas to the mash brought about more favourable wort-and beer properties and via a lower level of ageing components a better flavour stability. The head retention of the beers was less satisfactory. The addition of oxygengas to the mash caused negative effects on taste and flavour stability. However, the beer foam was improved, in particular if the oxygenation took place at higher mashing-temperatures. Mashing in temperatures of 62C and 67C caused a lower amount of ageing components and by this way a lesser degree of aged flavour. The restricted protein-modification brought about a lower level of polyphenols, a lower reducing-power, better foam figures, but a poorer colloidal stability. The result of the taste test of the 67C-beer was press favourable. A reduction of the mash-pH from 5.8 to 5.5 and to 5.2 created an increase of the ageing compounds as well as of the reducing power. However, the taste of the fresh and the aged beers was best at the pH 5.2. An addition of nitrogen gas enforced this effect, the addition of oxygen clearly inhibited it. Defatting the grist down to 25% of the original value promoted a better degradation of starch, β-glucan and protein. However, there was no influence an the ageing process of beer. On the contrary, the addition of the extracted fat to the grist led to the most inferior results in the fresh as well as in the aged beers.

Descriptors: Brewhouse, Flavour stability, beer staling, aroma profiles, carbonyle compounds

Monatsschrift fr Brauwissenschaft 53, No 11/12, 204-216, 2000