Session Chair:
Lene Bech (Senior Laboratory & Regulatory Manager, Carlsberg, DK)
Identification of key compounds affecting the property of bitterness in beer and their control
By Shunji Fujioka and Takako Inui, Suntory Japan
It is acknowledged that Bitter Units do not account for all sensory components contributing to the property of bitterness: as yet, brewing science has failed to unravel this situation. In this study, ‘Bitterness’ was deconstructed into three key components, ‘lingering’, ‘sharpness’ and ‘astringency’, and the score of ‘bitterness preference’ was negatively correlated with them by examining 14 commercial beers. Followingly, various compounds in beers, including cyclic bitter derivatives of iso -α-acid reported by Intelmann et al, were comprehensively analyzed using LC-orbitrap-MS.Then, multivariate analysis of the compounds and the sensory data was conducted. Results showed that cyclic bitter derivatives of iso -α-acid could negatively affect bitterness components. In order to control them, their behavior during wort boiling was examined. As results, their reaction kinetics were differ from those of iso -α-acid. Thus, this difference suggested that the duration of hop boiling could be used to control them. Finally, in brewing trials, shortening hop boiling indicated the decrease of those deleterious compounds: this resulted in an increase in the preferable bitterness property.
Impact of limonene degradation in beer-mix beverages on the sensory stability during shelf life
By Helmut Klein et al., Brauunion Austria
Beer-mix beverages show a different behavior during shelf life in terms of flavour stability. The staling mechanisms of beer have little relevance while the lemonade part with its strong fruity aromas is predominant. Our main interest therefore was to investigate the change of flavour substances originating from the lemonade part – especially volatile terpenes like limonene.Different types of beer-mix beverages and Radlers representing diverse flavours and alcohol levels have been investigated by multiple gas chromatographic methods as well as descriptive sensory analysis in fresh and forced aged samples. Limonene is the main aroma substance of citrus derived fruit compounds and is present in two stereoisomeric forms. During shelf life (R)-(+)-limonene shows a strong decrease whereas (S)-(-)-limonene is relatively stable. However, the (R)-(+)-limonene has a citrus like aroma whilst the (S)-(-)-limonene has a turpentine like one. In the sensory analysis of specific beer-mix beverages, we found a significant decrease of citrus-like aromas and a strong increase of soapy-turpentine flavours. This could be effected by the different stability of the limonene stereoisomers.