Determination of Lightstruck Character in Beer by Gas Chromatography-Mass Spectroscopy

Masuda, Shōgo; Kikuchi, Kaori; Harayama, Koichi; Sakai, Kazuhisa; Ikeda, Mitsuo

doi:10.1094/asbcj-58-0152

Cited by 15 publications

(16 citation statements)

References 3 publications

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“…Compared to the NMR spectroscopic data of the isohexenoyl side chain in 3 a, the methylene protons H À C2' are noticeably shifted upfield to d = 1.62 and 1.74 ppm, and the coupling to H À C3' in 4 a is divergent for each of the diastereotopic methylene protons Ha À C2' and Hb À C2', respectively. The large coupling constant of 3 JA C H T U N G T R E N N U N G (H,H) = 12.7 Hz measured between Ha À C2' and H À C3' clearly indicates that both carbon atoms are part of a cyclic system. Even more interesting, a weak coupling of 4 JA C H T U N G T R E N N U N G (H,H) = 1.8 Hz was observed between the protons HbÀC2' and H À C2'', which can only be explained by a new carboncarbon bond between C2'' and either C1' or C3', respectively (Scheme 2).…”

Section: Resultsmentioning

confidence: 98%

“…Within this process, one of the main hop constituents, the so-called a-acids (1), generally present as a mixture of cohumulone (1 a), humulone (1 b), and adhumulone (1 c), are well-known to be transformed by a rearrangement reaction to give a diastereomeric pair of socalled iso-a-acids (Scheme 1). [1] These isomerization products occur as cis (2) and trans isomers (3) and are considered to be the key bitter compounds in beer. [2] As a consequence of the three different alkanoyl side chains of the parent a-acids, these iso-a-acids occur as cis-and trans-configured isocohumulone (2 a, 3 a), isohumulone (2 b, 3 b), and isoadhumulone (2 c, 3 c), respectively.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, some storage-induced changes in the fraction of volatile aroma compounds have been successfully characterized and the corresponding off-flavor compounds identified. [3][4][5] In particular, photodegradation [6] and radical-assisted oxidation of iso-a-acids [7] are generally accepted to be responsible for the generation of potent off-odor compounds, but the available information on nonvolatile off-taste is rather fragmentary. Although aging of beer has long been known to induce a significant decrease in the intensity of the bitterness as well as a change of the bitter taste quality towards a long-lasting, lingering, and harsh bitterness and, in consequence, continues to cause severe quality problems for the brewing industry, [8][9][10] the molecular basis of the deterioration of that bitterness is not known.…”

Section: Introductionmentioning

confidence: 99%

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Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

Intelmann

Kummerlöwe

Haseleu

et al. 2009

Chemistry A European J

108

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Besides undesirable changes in the attractive aroma, a significant decrease in the intensity of the bitterness as well as a change of the taste into a lingering, harsh bitterness has long been known as a shelf-life limiting factor of beer. Multiple studies have demonstrated that the aging of beer induces a decrease of the total amount of cis- and trans-iso-alpha-acids, the well-known bitter principles of beer. Although the trans-iso-alpha-acids exclusively, not the cis-iso-alpha-acids, were found to be degraded upon storage of beer, the key transformation products formed exclusively from the trans isomers in beer are not known. In the present study, suitable model experiments followed by LC-MS/MS and sophisticated NMR spectroscopic experiments, including the measurement of residual dipolar couplings (RDCs) in gel-based alignment media as well as a novel broadband and B(1)-field-compensated incredible natural abundance double-quantum transfer experiment (INADEQUATE) pulse sequence, enabled the identification of a series of previously unknown trans-specific iso-alpha-acid transformation products, namely, tricyclocohumol, tricyclocohumene, isotricyclocohumene, tetracyclocohumol, and epitetracyclocohumol, respectively. HPLC-MS/MS analysis of these compounds, which exhibit the aforementioned harsh lingering bitter taste and have threshold concentrations ranging from 5 to 70 micromol L(-1), confirmed their generation during aging of beer and, for the first time, explained the storage-induced changes of the beer's bitter taste on a molecular level.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

Intelmann

Kummerlöwe

Haseleu

et al. 2009

Chemistry A European J

108

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show abstract

“…These calculations show that both molecules exist in a state with Figure 8. Proposed reaction mechanism explaining the formation of the tricyclic (4, 5, 6) and tetracyclic degradation products (7,8) from trans-iso-R-acids (3). Figure 9.…”

Section: Resultsmentioning

confidence: 99%

¹⁸O Stable Isotope Labeling, Quantitative Model Experiments, and Molecular Dynamics Simulation Studies on the Trans-Specific Degradation of the Bitter Tasting Iso-α-acids of Beer

Intelmann

Demmer

Desmer

et al. 2009

J. Agric. Food Chem.

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The typical bitterness of fresh beer is well-known to decrease in intensity and to change in quality with increasing age. This phenomenon was recently shown to be caused by the conversion of bitter tasting trans-iso-alpha-acids into lingering and harsh bitter tasting tri- and tetracyclic degradation products such as tricyclocohumol, tricyclocohumene, isotricyclocohumene, tetracyclocohumol, and epitetracyclocohumol. Interestingly, the formation of these compounds was shown to be trans-specific and the corresponding cis-iso-alpha-acids were found to be comparatively stable. Application of 18O stable isotope labeling as well as quantitative model studies combined with LC-MS/MS experiments, followed by computer-based molecular dynamics simulations revealed for the first time a conclusive mechanism explaining the stereospecific transformation of trans-iso-alpha-acids into the tri- and tetracyclic degradation products. This transformation was proposed to be induced by a proton-catalyzed carbon/carbon bond formation between the carbonyl atom C(1') of the isohexenoyl moiety and the alkene carbon C(2'') of the isoprenyl moiety of the trans-iso-alpha-acids.

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“…Exposure of beer to light generates 3-methyl-2-butene-1-thiol, which provides a skunky off-flavor in "sun-struck" or "light-struck" ales (123,124). This mercaptan has a sensory threshold of 0.05 ppb in beer.…”

Section: Sulfur Volatile Contributions To Off-flavors and Taintsmentioning

confidence: 99%

The Significance of Volatile Sulfur Compounds in Food Flavors

McGorrin

2011

ACS Symposium Series

105

106

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Volatile sulfur compounds are important contributors to the characteristic flavors and off-flavors of many foods. As a class, sulfur-containing flavor volatiles have low sensory detection thresholds, are present in low concentration and are often chemically labile, which can present measurement challenges. Advances in analytical separation techniques and instrumentation have enabled understandings of their occurrence and contributions to their relative sensory significance.Relating the chemistry and sensory contributions of volatile sulfur compounds to food flavor is an ongoing endeavor. The preminent quest in flavor research is to identify and categorize chemical constituents which provide unique sensory characteristics to the aroma and flavor of foods. Sulfur compounds contribute enzymatically-derived flavors in the Allium species (garlic, onion, chive) or Cruciform families (Brussels sprouts, broccoli, cabbage, cauliflower), and thermally-generated flavors such as roasted meat, chicken, seafood, and coffee. Volatile sulfur compounds play an important role in the aromas of bread, popcorn, nuts, potato products and wine, and contribute subtle flavor characteristics to cheddar cheese, chocolate and tropical fruit flavors, to name a few examples. Additional understandings of biosynthetic pathways, fermentation mechanisms, or thermal processes continue to evolve by which sulfur flavor constituents can be

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Determination of Lightstruck Character in Beer by Gas Chromatography-Mass Spectroscopy

Cited by 15 publications

References 3 publications

Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

¹⁸O Stable Isotope Labeling, Quantitative Model Experiments, and Molecular Dynamics Simulation Studies on the Trans-Specific Degradation of the Bitter Tasting Iso-α-acids of Beer

The Significance of Volatile Sulfur Compounds in Food Flavors

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Determination of Lightstruck Character in Beer by Gas Chromatography-Mass Spectroscopy

Cited by 15 publications

References 3 publications

Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

Structures of Storage‐Induced Transformation Products of the Beer’s Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LC–MS Techniques

18O Stable Isotope Labeling, Quantitative Model Experiments, and Molecular Dynamics Simulation Studies on the Trans-Specific Degradation of the Bitter Tasting Iso-α-acids of Beer

The Significance of Volatile Sulfur Compounds in Food Flavors

Contact Info

Product

Resources

About

¹⁸O Stable Isotope Labeling, Quantitative Model Experiments, and Molecular Dynamics Simulation Studies on the Trans-Specific Degradation of the Bitter Tasting Iso-α-acids of Beer