Spectrophotometric Determination of Humulone Complex and Lupulone in Hops

Alderton, Gordon; Bailey, GeoH.; Lewis, John B.; Stitt, Fred

doi:10.1021/ac60090a010

Cited by 54 publications

(13 citation statements)

References 8 publications

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“…Table 1 gives the experimental absorptivities of the samples shown in Figure 1 at the analysis wavelengths of 275, 325, and 355 nm, and the amounts of α-and β-acids (humulones and lupulones) and third component found using the above three-component analysis. Yet a third solution to this educational problem, and one that could be used in a nonmajors chemistry lab with no algebra, is to use the following equations: Equations 4 and 5 are similar to those given in Alderton et al, 1 but the coefficients are 1000 times smaller because Alderton's equations yield concentrations in mg/L. Even this simple, nonmathematical approach has its use in the more advanced lab.…”

Section: Discussionmentioning

confidence: 99%

A Multicomponent UV Analysis of α- and β-Acids in Hops

et al. 2011

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b S Supporting Information T his lab uses humulones (α-acids) and lupulones (β-acids) present in hops, a component of beer, to explore and explain several different chemical and mathematical concepts. The hop system is educationally engaging because it can be integrated into the curriculum at many different levels. In the nonmajors chemistry lab this experiment can be used to introduce the concept of an absolute method that does not require calibration versus a relative method that does. If a minor interfering species is ignored, the hop analysis can also be used at the general chemistry level to introduce the standard two-component analysis using high school algebra. At the chemistry major's analytical chemistry level the same lab can be used as a multicomponent analysis that includes an interfering species, and the mathematics behind the multicomponent analysis can be used as a bridge to the method of Gaussian elimination and matrix algebra to explain how systems of several equations and unknowns can be solved. At all levels a comparison of this method with the original, industry standard analysis method 1 can be used to illustrate a more "green" methodology in analytical methods development. This lab also can be used to expose students to units of specific absorptivity as well as the more often used unit of molar absorptivity. Finally, as a lab with a direct practical application to a real-world problem, a problem that will allow a student to interact with a brewer on a professional level, we predict that this exercise is one that the students will remember for years.Most analytical chemistry texts dealing with spectroscopy discuss the BeerÀLambert law,where A is the absorbance at a particular wavelength, ε is the absorption coefficient, l is the path length, and c is the concentration for a single absorbing species. In a two-component system the absorptions of the individual components add, soTo find the concentration of both components, the absorbance of the solution at two wavelengths must be obtained, and a system of two equations and two unknowns set up.Initially, the mixture of α-and β-acids present in a hop sample appears to be a simple two-component system that can be analyzed by standard techniques presented in most texts on UVÀvisible spectroscopic analysis. However, more careful analysis reveals that this system is a complex system containing at least two analytes and an additional interfering species.Hops, the inflorescence (cone) of the Humulus lupulus plant, contain both α-acids (humulones) and β-acids (lupulones), the major chemical components of which are shown in Figure 1. The quantity of α-and β-acids varies with the type of hop used, 2,3 how the hop was processed, 4 how it was stored, and how long it has ABSTRACT: A method is presented for the determination of α-and β-acids (humulones and lupulones) in a hops sample using a multicomponent UV spectroscopic analysis of a methanolic hop extract. When compared with standard methods, this lab can be considered "greener" because it uses smaller...

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Section: Discussionmentioning

confidence: 99%

A Multicomponent UV Analysis of α- and β-Acids in Hops

et al. 2011

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“…which are applicable to solutions containing tso-compounds as well as a and j3 adds. From the absorption curves of Alderton et al 2 it can be seen that solutions of a and j3 adds in alkaline methanol have common points at 230 m/u,. and 332 m/i.…”

Section: Methodsmentioning

confidence: 95%

Lupulin: Analysis and Usage

Askew¹

1965

Journal of the Institute of Brewing

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A high-grade lupulin from Californian hops was made up of 447% a adds, 33-6% (3 acids, soft and hard resins 5-5%, crude protein 4-9%, crude ash 1*5%, reducing sugars 0-6%, and structural material, etc., 9-6%. Tannins (3-9%) and a trace of anthocyanidins were present.Crushing of the lupulin is necessary for complete extraction of the acids; in petroleum-ether extracts the sum of a + J3 acids approximates closely to the total solids in the solution. Spectrophotometric examination of /so-octane extracts from distilled water or wort in which lupulin has been boiled can give misleading information. Data obtained from such extracts taken into alkaline methanol are more reliable and informative. At about pH 6-5 efficiency of conversion of a acids into fso-compounds was 95% in distilled water; /? acids were not appreciably changed.

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“…A 500-g sample from each plot was pressed into a bale to a density of 176 kg/m 3 (commercial standard). Bales were placed individually in polyethylene bags and stored at about 5 C until they were analyzed for alpha (humulone and its analogues) and beta (lupulone and its analogues) acid con tent by the method of Alderton et al (1).…”

Section: Methodsmentioning

confidence: 99%

Effects of Paraquat and Dinoseb in Hops

Zimmermann¹

1976

Weed sci.

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Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) at 1.1 and 2.2 kg/ha and paraquat + dinoseb (2-sec-butyl-4,6-dinitrophenol) at 1.1 + 0.7 kg/ha controlled redroot pigweed(Amaranthus retroflexusL.) and barnyardgrass [Echinochloa crus-galli(L.) Beauv.] in hops (Humulus lupulusL. ‘Yakima Cluster’) without reducing hop yield or the alpha and beta acid content of the hop cones. Three applications at about 3-week intervals were required to control weeds until harvest. Two applications controlled hop sucker growth. Paraquat at more than 0.6 kg/ha in the third application caused excessive reduction in hop sucker growth.

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Spectrophotometric Determination of Humulone Complex and Lupulone in Hops

Cited by 54 publications

References 8 publications

A Multicomponent UV Analysis of α- and β-Acids in Hops

A Multicomponent UV Analysis of α- and β-Acids in Hops

Lupulin: Analysis and Usage

Effects of Paraquat and Dinoseb in Hops

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