Changes in key hop‐derived compounds and their impact on perceived dry‐hop flavour in beers after storage at cold and ambient temperature

Abstract

Changes in hop-derived compounds of beer were evaluated over 10 months of storage at 3 and 20°C, revealing significant changes in the beers stored warm. Beer pH and colour increased, together with ‘hop creep’ through storage of unpasteurised dry-hopped beers. Hop bitter acids decreased moderately during storage at 20°C but not at 3°C and hop aroma compounds - key contributors to dry-hop flavour - were significantly depleted upon warm storage. Cold storage resulted in significant retention of these compounds in the beers, especially hop mono- and sesquiterpenes which exhibited the greatest losses after warm storage. The losses of hop aroma compounds were linked in part to association with polymeric crown cap liners (‘scalping’), the dynamic of which was further impacted by storage temperature. A wide range of hop aroma compounds were found to be abundant in the crown cap liners of bottled beers after storage, in contrast to canned beers which showed better retention of key hop aroma compounds (caryophyllene, myrcene and humulene) throughout storage. The impact of some of the chemical changes during storage was determined by sensory analysis. Changes in ‘bitter’, ‘tropical’ and ‘citrus’ fruit, ‘sweet’ and ‘malty’ attributes were all influenced by storage temperature and the given beer. Changes in ‘floral’, ‘fruity’, ‘sour/acidic’, ‘alcoholic’ and ‘lingering aftertaste’ were dependent on the beer, whilst changes in ‘spicy’ notes were dependent on storage temperature. These findings provide meaningful insights into the storage induced changes of dry-hop flavour in dry-hopped beers. © 2021 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.