Identification of U.S.-Grown Hop Cultivars by Hop Acid and Essential Oil Analyses

Kenny, S. T.

doi:10.1094/asbcj-48-0003

Cited by 10 publications

(16 citation statements)

References 2 publications

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“…Thus, our arbitrary list of aromatics includes components in all the main categories proposed by Nickerson and van Engel, 20 as well as β-myrcene, caryophyllene, farmecene, and humulene, which are important in the evaluation of new aromatic hop varieties 22,23 and/or the identification of hop varieties grown in the USA. 24 When comparing lines 2, 3, 6 and 7 of Table 2, it is possible to assess seasonal effects (1999 harvest versus 2000 harvest) on hop extract quality. It is important to mention that all samples were similarly harvested, dried and stored, but that samples from 2000 were ground and extracted just 3 months after harvest, whereas those from 1999 were treated 16 months after harvest.…”

Section: Results and Discussion Selection Of Extraction Conditionsmentioning

confidence: 99%

Supercritical CO₂ extraction of Chilean hop (Humulus lupulus) ecotypes

et al. 2003

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Hops (Humulus lupulus L) have very stringent requirements of diurnal light hours during flowering. Thus, the beer industry is permanently assessing new agricultural land to grow hops, southern Chile being an excellent candidate for their introduction. Supercritical carbon dioxide extraction procedures were implemented to assess Chilean hop ecotypes. Based on results of a preliminary study with commercial samples (cv Nugget), 200 bar and 40 • C were selected as extraction conditions. Very limited increases in extraction rate were observed when applying pressures >200 bar; such pressures did not speed up the extraction of α-acids (bitter flavor principles), but rather increased the co-extraction of undesirable compounds (hard resins and chlorophyll pigments). On the other hand, the effects of retrograde condensation phenomena were just starting to subside at 200 bar, and thermal damage of samples could increase at >40 • C. Ground cone samples of five local hop ecotypes, originating from Osorno, La Junta, Coyhaique and Elizalde Lake, were subsequently tested. Osorno exhibited a higher yield (65 g kg −1 oleoresin/substrate) than other Chilean ecotypes. Moreover, Osorno extract had a light yellowish color, as well as a higher content of bitter flavors (157 g kg −1 α-acid/extract) and 1.5-7.1 times more representative aroma compounds than extracts of the other ecotypes. However, all these indicators were very low compared with the commercial Nugget sample (134 g kg −1 oleoresin/substrate, 383 g kg −1 α-acid/extract, 14 times more aroma compounds than Osorno ecotype).

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Section: Results and Discussion Selection Of Extraction Conditionsmentioning

confidence: 99%

Supercritical CO₂ extraction of Chilean hop (Humulus lupulus) ecotypes

et al. 2003

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“…In 1990, Kenny published a key for the varietal characterization of hops based on six ratios calculated from the amounts of 10 essential oil components. Other varietal identification models, based on the hop oil analysis and composition, were proposed by Kralj et al .…”

Section: Hop Essential Oilsmentioning

confidence: 99%

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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“…For example, the Czech hop variety Saaz is unique by its very high content of β-farnesen (Perpéte et al 1998), while Magnum variety contains a high amount of p-coumaric acid (Goiris et al 2005). Kenny described a unique content of cohumulone for Nugget variety (Kenny 1990). Indeed, all of those factors are highly influenced by various effects, like the breeding area (Green 1997), climatic conditions (de Keukeleire et al 2007), manufacturing technique (Srečec et al 2009), or storage temperature (Canbas et al 2001).…”

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confidence: 99%

“…Some authors propose identification methods based only on the specific contents of the selected essential oils (Peacock & McCarty 1992;Eri et al 2000), other authors suggest to use the contents of hop essential oils and bitter acids (Kenny 1990). De Cooman et al (1998 described some characteristic markers (characteristic contents of bitter acids, oils, and flavonoids) in the Saaz, Wye Target, and Nugget cultivars.…”

mentioning

confidence: 99%

Comparison of Czech hop cultivars based on their contenst of secondary metabolites

Jelínek¹,

Sneberger²,

Karabín³

et al. 2010

Czech J. Food Sci.

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Jelínek L., Šneberger M., Karabín M., Dostálek P. (2010) Seven Czech hop varieties (dry hop cones) coming from the harvest of 2008 (Agnus, Bor, Harmonie, Premiant, Rubín, Sládek, and Saaz) were compared for their composition depending on their varietal differentiation. These cultivars were analysed for the contents of α-and β-bitter acids analogues, essential oils, and polyphenols. Hop essential oil constituents significantly contribute to the individual hop varieties. The dichotomous key for the authentication of Czech hop varieties was established based on some characteristic varietal markers.

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Identification of U.S.-Grown Hop Cultivars by Hop Acid and Essential Oil Analyses

Cited by 10 publications

References 2 publications

Supercritical CO₂ extraction of Chilean hop (Humulus lupulus) ecotypes

Supercritical CO₂ extraction of Chilean hop (Humulus lupulus) ecotypes

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

Comparison of Czech hop cultivars based on their contenst of secondary metabolites

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Identification of U.S.-Grown Hop Cultivars by Hop Acid and Essential Oil Analyses

Cited by 10 publications

References 2 publications

Supercritical CO2 extraction of Chilean hop (Humulus lupulus) ecotypes

Supercritical CO2 extraction of Chilean hop (Humulus lupulus) ecotypes

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

Comparison of Czech hop cultivars based on their contenst of secondary metabolites

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Product

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Supercritical CO₂ extraction of Chilean hop (Humulus lupulus) ecotypes

Supercritical CO₂ extraction of Chilean hop (Humulus lupulus) ecotypes