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The Bitter, Twisted Truth of the Hop 50 Years of Hop Chemistry

Joint Technical Meeting: MBAA Rocky Mountain District & ASBC Wild West Chapter November 6 th , 2008. The Bitter, Twisted Truth of the Hop 50 Years of Hop Chemistry. David Ryder, Patrick Ting & Sue Kay MillerCoors Milwaukee, USA. O. O. R. O. OH. O. O. O. O. HO. R. R. HO. O.

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The Bitter, Twisted Truth of the Hop 50 Years of Hop Chemistry

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  1. Joint Technical Meeting: MBAA Rocky Mountain District & ASBC Wild West ChapterNovember 6th, 2008 The Bitter, Twisted Truth of the Hop 50 Years of Hop Chemistry David Ryder, Patrick Ting & Sue Kay MillerCoors Milwaukee, USA

  2. O O R O OH O O O O HO R R HO O OH OH O OH CH3 CH3 O O CH3 R H OH O O O SH hv R HO SH- OH O Unlocking 50 yearsof hop chemistry

  3. Flavor and Flavor Stability Characterization of Bittering Acids UnfoldingHOPChemistry (1958-2008) Improved Utilization Light Stability 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008

  4. 1950’s-1980’s Characterization of Bittering Acids

  5. O O R Characterization of Humulone (Cook, Harrison, Carson, Verzele) O OH OH R= CH2CH(CH3)2 a-Fraction separated into co, n and adhumulone(Rigby, Bethune, Meilgaard) R =CH(CH3)2co- CH2CH(CH3)2n- CHCH3CH2CH3ad-

  6. R O O O O O OH OH R HO OH O • Determined a-acids are converted to iso-a- acids in the brewing process. • Quantified contribution of iso-a-acids to beer bitterness. (Rigby, Bethune, Meilgaard)

  7. cis-Iso--Acids Established R-configuration of a-acids and stereoisomers of iso-a-acids. (De Keukeleire, Verzele) O O O O O O O HO R + R R H H OH OH O OH OH OH O trans-Iso--Acids a-Acids

  8. O O R O OH b-Fraction separated intoco, n and adlupulone (Riedl, Verzele, Govaert, Howard, Rigby, Bethune) R= CH(CH3)2co- CH2CH(CH3)2n- CHCH3CH2CH3ad-

  9. 1950’s-1990’s Improved Utilization

  10. Commercial Production Organic Solvents • Hop extracts - Concentrated a-acids • Pre-isomerized extracts - Kettle extract • Post kettle extract by Carlton & United Breweries Non-Solvent •Isomerized hop pellets by Grant of S.S. Steiner

  11. 1950’s-2008 Light Stability

  12. In the 50’s, Miller Brewing discovered under UV or visible light (in the presence of riboflavin) iso-a-acids and sulfurcaused light instability in beer.

  13. O O SH R hv HO SH- OH O 3-Methyl-2-Butene-1-Thiol (3M2B1T or MBT) Thesun-struckor skunky flavor(3M2B1T) and the mechanism of its evolution was later characterized by Kuroiwa, et al. of Kirin Breweries in the early 60’s.

  14. O O R R R OH- NaBH4 HO HO OH OH O OH O OH OH a-Acids Iso-a-acids r-Iso-a-acids O O O Miller Brewingpatented a commercially viable process to produce light stable r-iso-a-acids. O In 1961, light stablebeer made its debut in flint bottles.

  15. 1970’s-2008 Organic Solvent Free Hop Extract

  16. In 1975, Laws et al. of BRF introduced liquid CO2 hop extracts(rich in a-acids, b-acids, and essential oils) under 1000 psi (69 bar) and 50°F (10°C), which was then commercialized by Carlton & United Breweries. In 1978, Muller, Vitathum and Huber developed supercritical CO2 hop extractionunder 3000 psi (207 bar) and 110°F (43°C). Supercritical/Liquid CO2 Extraction of Hops

  17. O O R HO OH O Tetrahydroiso-a-acids

  18. O O O O R R HO OH O OH O OH Mg++/OH- H2 Pd/C a-Acids Iso-a-acids O O R HO OH O OH O Tetrahydroiso-a-acids R O O O2 HO OH R H2 Mg++/OH- NaBH4 Pd/C O OH Hexahydroiso-a-acids Tetrahydrodesoxy -a-acids b-Acids Hexahydro-b-acids Chemistry of Tetrahydroiso-a-acids

  19. 15 14 13 Tetrahydroiso-a-acids 12 Sensory Bitterness Intensity 11 10 9 8 0 10 20 30 Comparison of Sensory vs. Analytical Bitterness Iso-a-acids r-Iso-a-acids Analytical BU

  20. Bitterness Intensity Differences Between High and Low Isocohumulone(Shellhammer et al. 2004)

  21. Tetrahydroiso-a-acids S-S-SCH3 S-S-CH3 S-H O O R HO OH O Under UV or visible light the tetrahydroiso-a-acids do notproduce 3M2B1T which also leads to two newly discovered light struck flavors. 3M2B1T = 3M2B-methyldisulfide 3M2B-methyltrisulfide Tetrahydroiso-a-acidsnot only provide excellent light protection in beer, but also…

  22. 1970’s-2008 Foam Improvement

  23. POWERFULLY ENHANCE FOAM STABILITY • Beer foam potential requires the interaction of hop bittering acids and beer proteins. • The more bitter the beer, the better the foam.Tetrahydroiso-a-acids • Preferentially interact with the most foam stabilizing compound in beer, LTP (barley lipid transfer protein), due to hydrophobic interactions. • Retain foam potential because they do not degrade while Iso-a-acids degrade over beer shelf life. • Protect the foamin non-pasteurized beer even while yeast proteinase A slowly destroys the foam proteins.

  24. 1970’s-2008 Anti-Microbial

  25. Hop acids have remarkable antibacterial properties against gram positive organisms. (Teuber 1970) • Hop acids actas ionophorestransporting ions across the cell membranes of susceptible bacteria. This disrupts ion gradients across the membranes causing leakage, starvation and cell death. (Teuber and Schmalreck 1973) • The greater hydrophobicity of the undissociated form of the hop acids enhances the ionophoric nature of the hop molecule resulting in increased antibacterial activity. (Simpson 1991-1993) • Tetrahydroiso-a-acids and Hexahydro-b-acids are the most antimicrobial of hops acids, but at two different pH values.(Miller Brewing 1987 and 1995) • Tetrahydroiso-a-acids show more effective anti-microbial action than iso-a-acids during the acid washing of yeast. (Miller Brewing 2001)

  26. Effects of Hops on Disinfecting Brewer's Yeast Seeded with an Acid Resistant Pediococcus

  27. Effects of Tetrahydroiso-a-acids on Disinfecting Brewer's Yeast Seeded with an Acid Resistant Pediococcus(at pH 2.3)

  28. The Relative Anti-Microbial Activityof Hop Compounds

  29. Fruit juices (Alicyclobacillus) Food Applications (Listeria, Clostridium botulinum or Bacillus spores) Oral care products (Streptococcus mutans) Feminine hygiene products, baby wipes, diapers (Staphylococcal) Skin care products (Propionobacterium acnes and Staphylococcus aureus)

  30. Key Takeaways Hydrophobicity Molecular Structures of isoa-acids derivatives

  31. 1950’s-2008 Flavor

  32. Flavor is not all about bitterness… Hops also provide spicy, floral, citrus aroma and flavor, and “mouthfeel” characteristics to beer. Early extensive investigations were conducted to correlate the hop oil compoundsto various hoppy flavors in beer.

  33. Chapman’s early studies (1895-1929) • Howard (BRF) • Howard and Stevens (BRF) • Irwin (Labatt) • Fukuoka and Kowaka (Kirin) • Peacock and Deinzer(Oregon State) • Tressl (Technischen University, Berlin) • Harley and Peppard (BRF) • Lam, Foster II, and Deinzer (Oregon State) • And many others……….. Hop Oils > 300 Compounds 70% Hydrocarbons 30% Oxygenated Compounds

  34. No single hop oilcomponent has been shown unequivocally to be present in kettle-hopped beer. • Buttery, Black, Lewis, and Ling • Sandra and Verzele • Peacock and Denzer • Rigby • Miller Brewing The chemistry of hop flavoris still not properly understood.

  35. Spicy fraction Floral fraction Citrus fraction Fractionation of hop oils (Haley, Peppard, Westwood et al. of BRF in 1985) Commercial post-fermentation products became available to mimic late and dry (resinous) hopping. However, these fractions do not produce true early kettle hop flavor.

  36. Glycosides:A Secret of Hop Flavor Revealed In 1998, Miller Brewing found that the cellulose portion (hop solids) after CO2 extraction contains a mixture of water soluble substances composed of 92.4 mole% of glucose with a majority of 55% terminal and other linkages.

  37. Glucose Terminal 6-linked 1,2-linked 2,6-linked 2,3,6-linked % 55 22 10 10 3 CH2 HO O HO O HO HO CH2 O O HO OH HO HO HO CH2 O HO O HO O CH2 O O HO OH Linalool (Aglycone) HO O CH2 O O HO OH O O Glycosides: A Secret of Hop Flavor Revealed • The terminal glucose made of a glucose molecule and an aromatic compound (aglycone) called b-glycosides. • A group of b-glycosides survive the kettle boil because they are water soluble and non-volatile. OH H H O HO O HO H HO H H Linalyl b-Glycoside

  38. OH H H O O HO HO H HO H H Glycosides:A Secret of Hop Flavor Revealed • Yeast can hydrolyze b-glycosides and further convert aglycones into hop flavor. • The b-glycosides present in the hop cellulose portion contribute the true kettle hop flavor in beer. • Further supported by • H. Kollmannsberger and S. Nitz, 2002 • M. Biendl, H. Kollmannsberger and S. Nitz, 2003 • L. Daenen, D. Saison, L. De Cooman, G. Derdelinckx, H., Verachtert, F. R. Delvaux, 2006 Linalool (Aglycones) + Glucose HOP FLAVOR COMPOUNDS

  39. DIRECT ANALYSIS OF HOP b-GLYCOSIDES

  40. 1990’s-2008 Flavor Stability

  41. REACTIVE OXYGEN SPECIES ORFREE RADICALS are detrimental to beer flavor stability or shelf life..

  42. Which hop compounds are antioxidants or antiradicals? That depends..

  43. Miller Brewingdetermined the antioxidant properties against the stable DPPH free radical.

  44. Some specific anti-oxidative polyphenolspresent in the hop cellulose portion: • Catechin, dimer, trimer and tetramer • b-Glycosides of kaempferol and quercetin • Xanthohumol

  45. O O SH hv R HO O O SH- OH O R O OH R 3 O H B RO O A C CH3 O R 1 CH3 O O H CH3 O O O O R R HO OH O OH O OH OH H H O HO HO O OH H H H A pioneer in the hop industry 50 Years of Hop Chemistry Dedicated to Dr. Francis Lloyd Rigby 1918 - 2008

  46. Acknowledgements • Lance Lusk • William Maca • Jason Pratt • Jay Refling • Linda Ting • Lance Lusk • William Maca • Jason Pratt • Jay Refling • Linda Ting

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