Pilot trials on the influence of the various mash parameters on the properties of wort and beer with particular respect to flavour stability

Various mash-parameters have been investigated with respect to the beer pro perties flavour/taste and flavour stability. The test brews took place in t he scales of 60, 9 and 220 litres. Worts and beers were analysed according to conventional methods as well as by three different methods of multidimen sional gas chromatography and mass spectrometry. The organoleptic evaluatio n 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 prope rties and via a lower level of ageing components a better flavour stability . The head retention of the beers was less satisfactory. The addition of ox ygen as 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 62 degree sC and 67 degreesC caused a low er amount of ageing components and by this way a lesser degree of aged flavour. The restricted protein-modification br ought about a lower level of polyphenols, a lower reducing-power, better fo am figures, but a poorer colloidal stability. The result of the taste test of the 67 degreesC-beer was press favourable. A reduction of the mash-pH fr om 5.8 to 5.5 and to 5.2 created an increase of the ageing compounds as wel l as of the reducing power. However, the taste of the fresh and the aged be ers was best at the pH 5.2. An addition of nitrogen gas enforced this effec t, the addition of oxygen clearly inhibited it. Defatting the grist down to 25% of the original value promoted a better degradation of starch, beta -g lucan 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.