Hop Resins and Beer Flavour Iv. Observations Concerning Hard Resin

Ashurst, Philip R.; Whitear, A. L.

doi:10.1002/j.2050-0416.1965.tb02023.x

Cited by 9 publications

(6 citation statements)

References 2 publications

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“…As hops age during storage, the percentage of soft resin falls while that of the hard resin increases (58). In 1964, Ashurst et al (59) inconclusively addressed the question of what constituents are responsible for the bittering ability of stored hops when the α-acids have been transformed into other substances. At that point, it had been recognized for many years that the resins of the hop undergo several changes during storage: the αand β-acids become oxidized, the products still being analytically classed as soft resins, while further oxidation results in gradual transformation to hard resins.…”

Section: Hard Resinsmentioning

confidence: 99%

“…At that point, it had been recognized for many years that the resins of the hop undergo several changes during storage: the α ‐ and β ‐acids become oxidized, the products still being analytically classed as soft resins, while further oxidation results in gradual transformation to hard resins. Thus, the α ‐ and β ‐acids decrease continually during storage while the amount of uncharacterized soft resin increases at first and then decreases as the hard resin steadily increases . While some authors automatically considered oxidized soft resins to be hard resins, others considered the uncharacterized soft resins in old hops to be the intermediate deterioration products of the α ‐ or β ‐acids which, upon further oxidation, will ultimately turn into hard resins.…”

Section: Hop Chemistrymentioning

confidence: 99%

“…Thus, the α ‐ and β ‐acids decrease continually during storage while the amount of uncharacterized soft resin increases at first and then decreases as the hard resin steadily increases . While some authors automatically considered oxidized soft resins to be hard resins, others considered the uncharacterized soft resins in old hops to be the intermediate deterioration products of the α ‐ or β ‐acids which, upon further oxidation, will ultimately turn into hard resins. It is believed that these intermediate deterioration products have brewing value, but the exact role of the oxidation products, be it oxidized soft resins or hard resins, in the brewing process is not fully understood .…”

Section: Hop Chemistrymentioning

confidence: 99%

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Humulus lupulus- a story that begs to be told. A review

Schönberger²,

et al. 2014

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The hop cones of the female plant of the common hop species Humulus lupulus L. are grown almost exclusively for the brewing industry. Only the cones of the female plants are able to secrete the fine yellow resinous powder (i.e. lupulin glands). It is in these lupulin glands that the main brewing principles of hops, the resins and essential oils, are synthesized and accumulated. Hops are of interest to the brewer since they impart the typical bitter taste and aroma to beer and are responsible for the perceived hop character. In addition to the comfortable bitterness and the refreshing hoppy aroma delivered by hops, the hop acids also contribute to the overall microbial stability of beer. Another benefit of the hop resins is that they help enhance and stabilize beer foam and promote foam lacing. In an attempt to understand these contributions, the very complex nature of the chemical composition of hops is reviewed. First, a general overview of the hop chemistry and nomenclature is presented. Then, the different hop resins found in the lupulin glands of the hop cones are discussed in detail. The major hop bitter acids (α-and β-acids) and the latest findings on the absolute configuration of the cis and trans iso-α-acids are discussed. Special attention is given to the hard resins; the known δ-resin is reviewed and the ε-resin is introduced. Recent data on the bittering potential and the antimicrobial properties of both hard resin fractions are disclosed. Attention is also given to the numerous essential oil constituents as well as their contributions to beer aroma. In addition to the aroma contribution of the well-known essential oil compounds, a number of recently identified sulfur compounds and their impact on beer aroma are reviewed. The hop polyphenols and their potential health benefits are also addressed. Subsequently, the importance of hops in brewing is examined and the contributions of hops to beer quality are explained. Finally, the beer and hop market of the last century, as well as the new trends in brewing, are discussed in detail. Hop research is an ever growing field of central importance to the brewing industry, even in areas that are not traditionally associated with hops and brewing. This article attempts to give a general overview of the different areas of hop research while assessing the latest advances in hop science and their impact on brewing.

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Section: Hard Resinsmentioning

confidence: 99%

Section: Hop Chemistrymentioning

confidence: 99%

Section: Hop Chemistrymentioning

confidence: 99%

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Humulus lupulus- a story that begs to be told. A review

Schönberger²,

et al. 2014

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“…The analysis of hop resins has been reviewed by Hudson (212,213), and subsequent workers (29,47,216,409) have discussed the significance of such analyses.…”

Section: Chemical Composition Of Hopsmentioning

confidence: 99%

The Chemistry of Hop Constituents

Stevens¹

1967

Chem. Rev.

121

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“…1 The effects of storage at high temperatures, or under conditions that promote degradation of the essential oil fraction, results in some changes which are detrimental to the overall brewing value of the hop. Thus hops stored at high temperatures for even a short period become cheesey and would no longer be suitable for dry hopping.…”

Section: Discussionmentioning

confidence: 99%