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.

The Influence of Hop Phenolic Compounds on Dry Hopping Beer Quality

“…The formation of the colloidal structure of dry hopping beer's samples continued more intensively at the fermentation stage in the difference from the kettle hopping beer's samples, due to the extraction of bitter, phenolic, and essential organic compounds from hop preparations, which is confirmed by other authors [44,49]. Researchers have noted the simultaneous extraction of α-bitter resins and the loss of iso-α-acid during dry-hopping through adsorption on yeast cells and hop preparation particles, the effect of the process temperature, and the pH change of beer in the upward direction [50,51].…”

“…In our opinion, during the dry hopping beer's production complex extraction, biotransformation, adsorption of bitter, phenolic, and ester compounds in the presence of yeast take place, which, among other things, affects the compounds that provide color formation of beer (melanoidins, polyphenols, caramels, etc.) [44].…”

Biotransformation of Hops-Derived Compounds in Beer – A Review

“…They are designed to maximize the extraction of essential oils during dry-hopping, as well as reduce dry-hopping time, hop consumption, and beer loss. At the same time, they minimize the introduction of oxygen, which is known to degrade aroma stability and increase the formation of staling aromas (Kemp et al, 2021;Podeszwa & Harasym, 2016).…”

Physicochemical and Sensory Properties of Czech Lager Beers with Increasing Original Wort Extract Values during Cold Storage

“…Hops are one of the four basic ingredients in beer production; in addition to adding flavor and aroma, their main contribution to the finished beer is highly associated with the bitterness obtained during boiling of wort with hops. In particular, iso-α-acids, which are the products of the isomerization of α-bitter acids present in hops during the boiling of wort, are the main contributors to the bitterness of beer [ 28 , 29 ]. The highest bitterness values were observed for the CB11.5 and CB12.0 beer samples, respectively.…”