ntifico Technological possibilities for transferringY theTU reiinBerlin(VLB) h the colour of dark barley (Hordeum vulgare L.) into mash and wort to produce beers with a reddish hue

In some barley (Hordeum vulgare L.) varieties, reddish-purple anthocyanins and black allomelanins are found in addition to the carotenoids. While melanins are absolutely insoluble in water as well as alcohol and therefore cannot be used in beverage production, anthocyanins are known to provide the characteristic colour of numerous juices and red wines. One focus of this study was to assess the technological possibilities of producing a red coloured beer from coloured barley. The biggest obstacles in conventional production processes are the high pH value of the unfermented mash and wort as well as the immense thermal stress caused by wort boiling. The influence of mash pH, wort boiling and hop addition were investigated in several trials on an experimental level in the lab. No classic brewing trials were conducted. A classic congress mashing process followed by immediate acidification was able to achieve a red colouring of the mash at pH values suitable for consumption. However, delaying acidification by just one day ensured that the anthocyanins contained remained in colourless form. Even a 15 -minute wort boiling significantly and irreversibly affected the colour. The addition of iso-alpha-acid to an acidified extract resulted in a weak but significant decrease in anthocyanin colouration. While the results of the study do not provide guidance for brewing a red beer, this does not seem impossible and further research may allow the production of coloured beers within the framework of the purity law.