How is beer made? Hop Quality A Brewer s Perspective Thomas H. Shellhammer Ph.D. Nor Wester Professor of Fermentation Science Oregon State University, Corvallis, Oregon, USA Barley Water Hops Yeast Barley Malting Inside the brewery! Steeping - grain hydration! Germination kernel modification " Enzymes produced that will be used by brewers! Kilning color & aroma Mashing # Boiling # Fermenting # Finishing # Packaging
Mashing Boiling From M. Jackson. 1993. Beer Companion From Krones Inc, 2001. The Way to Good Beer Large copper kettle Hops humulus lupulus
Lupulin glands Fermentation From M. Jackson. 1993. Beer Companion
Finishing! Maturation! Carbonation! Filtration! Packaging Where are hops added? On the hot side " To boiling wort! At the beginning (primarily for bitterness)! At the end (primarily for aroma)! After boiling but right before cooling (just aroma) On the cold side dry hopping " To beer! Solely for aroma Lupulin glands Hops composition Principle)Components! Concentra0on)(%w/w)! Cellulose!+!lignin! 40.0!/!50.0! Protein! 15.0! Alpha!acids! 2.0!/!17.0! Beta!acids! 2.0!/!10.0! Water! 8.0!/!12.0! Minerals! 8.0! Polyphenols!and!tannins! 3.0!/!6.0! Lipids!and!faFy!acids! 1.0!/!5.0! Hop!oil! 0.5!/!3.0! Monosaccharides! 2.0! PecHn! 2.0! European Brewery Convention Hops and Hop Products, Manual of Good Practice; Getranke - Fachverlag Hans Carl: Nurnberg, Germany, 1997.
Hop Acids α & β Acids The most important reaction in hop chemistry? Analysis of hop resins in hops Lead conductance value for measuring alpha acids in hops! Conductometric! Spectrophotometric! HPLC
UV spectra for methanol extracts of hops The Hop Storage Index (HSI) (HSI) = A 275 /A 325 Hop Deterioration During Storage HSI data 1970
Bittering can stay constant during storage Abused hops still produce bitter beer The IBU analysis Liquid-Liquid extraction of bitter compounds from beer Strong Acid Adds excess hydrogen ions to solution protonating all carboxylic acid functional groups + Non-Polar Solvent When functional groups are charged at a lower ph they are more non-polar 3 N Hydrochloric Acid 2,2,4 trimethylpentane + Beer Bitter compounds Iso alpha acids Oxidized hop acids Polyphenols Non-bitter compounds Alpha acids Extraction removes more than just Isos Non Polar Phase - TMP Iso-Alpha Acids Alpha Acids Oxidized hop acids Polyphenols Measure the absorbance at 275 nm Absorbance @275 x 50 = Bittering Units Polar Phase - Beer 1 BU 1 ppm iso-alpha acid
Correlation between total IAA & IBU BU increase due to hop polyphenols IBU 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 y = 1.2x + 2.0 R² = 0.905 Bitterness Units 40 35 30 25 20 15 10 Iso-alpha acids 0.1 ppm Alpha acids 0.0 ppm Humulinones 0.7 ppm 10.0 5 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Iso alpha acids concentration [ppm] 0 0 50 100 150 200 250 300 Total polyphenols (ppm) Terminology Alpha and Iso-Alpha Acids by HPLC Chromatography The method of separation Chromatograph The instrument of separation Chromatogram The visual output of the separation
HPLC Process Flow High Performance Liquid Chromatography! Atmospheric pressure Separation! Separation variables can be manipulated based on target analyte! non-volatile analysis Beer Sample DAD1 A, Sig=270,4 Ref=360,100 (VAA 6-18-13\VAA 6-18-13 2013-06-19 12-22-20\002-0301.D) Correlation between total IAA & IBU 90.0 80.0 400 70.0 300 200 isocohumulone isohumulone IBU / Sensory Score (0-15) 60.0 50.0 40.0 30.0 isoadhumulone 20.0 100 10.0 0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Total iso via HPLC [ppm] 2.5 5 7.5 10 12
Correlation between IAA & IBU & Sensory Dry hopping study with Cascade pellets IBU / Sensory Score (0-15) 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 IBU Sensory, AVG Overall)Aroma)(0:15)) Aroma)during)dry)hopping) 12! 10! 8! Pumped! 6! Passive! 4! 2! 0! 0! 100! 200! 300! 400! Dry)hopping)0me)(hours)) BiDerness)Intensity)(0:15)) BiDerness)during)dry)hopping) 12! 10! 8! Pumped! 6! Passive! 4! 2! 0! 0! 100! 200! 300! 400! Dry)hopping)0me)(hours)) 10.0 0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 Total iso via HPLC [ppm] Dry hopping study with Cascade pellets Polyphenol)Conc)(ppm)) Correla0ons)with)biDerness)during)dry)hopping) 340! 20! 320! 19! 300! 18! 17! 280! 16! 260! 15! 240! 14! 220! Polyphenol! Iso!Alpha! 13! 200! 12! 5! 6! 7! 8! 9! 10! 11! BiDerness)Intensity)(0:15)) Iso)Alpha)Acid)Conc)(ppm)) Dry hopping study with Cascade pellets Overall)Aroma)Intensity)(0:15)) 10! 9! 8! 7! 6! 5! Correla0ons)between)aroma)and)biDernesss) during)dry)hopping) 4! 5! 6! 7! 8! 9! 10! 11! BiDerness)Intensity)(0:15))
Hop acids quality! Total alpha acids are important! HSI is important! Cohumulone not important " Shellhammer s opinion! The IBU measures more than Isos " 1 BU 1 ppm Iso alpha acids Hops composition Principle)Components! Concentra0on)(%w/w)! Cellulose!+!lignin! 40.0!/!50.0! Protein! 15.0! Alpha!acids! 2.0!/!17.0! Beta!acids! 2.0!/!10.0! Water! 8.0!/!12.0! Minerals! 8.0! Polyphenols!and!tannins! 3.0!!6.0! Lipids!and!faFy!acids! 1.0!/!5.0! Hop!oil! 0.5!/!3.0! Monosaccharides! 2.0! PecHn! 2.0! European Brewery Convention Hops and Hop Products, Manual of Good Practice; Getranke - Fachverlag Hans Carl: Nurnberg, Germany, 1997. Mt. Hood Maturity Study (Probasco) Mt. Hood Maturity Study (Probasco) Alpha)Acids)(%)) 10! 9! 8! 7! 6! 2! 5! 1.5! 4! 3! 1! 3.5! 3! 2! Alpha!Acids!(%)! 1! Total!Oil! 0.5! 0! 0! /30! /25! /20! /15! /10! /5! 0! 5! 10! 15! Days)Pre:/Post:Harvest) 2.5! Oil)Content)(mg/100)ml)) Alpha)Acids)(%)) 10! 9! 8! 7! 6! 2! 5! 1.5! 4! 3! Cone!Appearance!and!Completeness! 1! 3.5! 3! 2! Alpha!Acids!(%)! 1! Total!Oil! 0.5! 0! 0! /30! /25! /20! /15! /10! /5! 0! 5! 10! 15! Days)Pre:/Post:Harvest) 2.5! Oil)Content)(mg/100)ml))
Hop Oil Composition Schönberger, C.; Kostelecky, T. 125th Anniversary Review: The Role of Hops in Brewing. J. Inst. Brew 2011, 117, 259 267. Hop!Oil!Compounds!of!Interest! Compound)Name) Classifica0on) Descrip0on) α/pinene! Hydrocarbon, Monoterpene Pine β/pinene! Hydrocarbon, Monoterpne Confierous Pine, woody β/myrcene! Hydrocarbon, Monoterpene Green, balsam, slightly metallic Limonene! Hydrocarbon, Monoterpene Citrus, Orange ρ/cymene! Hydrocarbon, Monoterpene like Orange, Woody, Spicy Caryophyllene! Hydrocarbon, Sesquiterpene Woody, Carrot E,!β!/Farnesene! Hydrocarbon, Sesquiterpene Green, woody, weedy, herbal, pine and gin Humulene! Hydrocarbon, Sesquiterpene Woody Methyl!heptonoate! Oxygenated, Ester Sweet, fruity, peach, apricot, green, berry Geraniol! Oxygenated, Monoterpene Alcohol Sweet floral, perfumy Linalool! Oxygenated, Monoterpene Alcohol Floral, Orange Citronellol! Oxygenated, Monoterpene Floral, Rose Citrus Farnesol! Oxygenated, Sesquiterpene Alcohol Spicy Citral! Oxygenated, other Sweet Citrus Geranyl!Acetate! Oxygenated, Monoterpene or ester Floral, Sweet Citrus Humulene!Epoxide!I! Oxygenated, Epoxide Hay-like Humulene!Epoxide!2! Oxygenated, Epoxide Cedar, Lime Harvest Timeline Willamette Cascade Harvest Dates by Farm and Year 8/17 8/19 8/21 8/23 8/25 8/27 8/29 8/31 9/2 9/4 9/6 9/8 9/10 9/12 9/14 9/16 Early Typical Late
Harvest Timeline Traditional Brewing Quality Parameters Willamette Harvest Dates by Farm and Year 7 days 4 days Early Typical Late 8/17 8/19 8/21 8/23 8/25 8/27 8/29 8/31 9/2 9/4 9/6 9/8 9/10 9/12 9/14 9/16 H.S.I. H.S.I. 0.30 0.25 0.20 0.15 0.10 Cascade Willamette Alpha Acids % α-acids 9.0 8.0 7.0 6.0 5.0 4.0 3.0 Cascade Willamette Cascade 8 days 6 days 8 days 0.05 0.00 Early Typical Late Harvest Point 2.0 1.0 0.0 Early Typical Late Harvest Point Total Essential Oil Cascade Essential Oil 3.00 Cascade Willamette 3.00 2010 Farm I 2011 Farm I 2010 Farm II 2011 Farm II Essential Oil (ml/100g) 2.50 2.00 1.50 1.00 0.50 Essential Oil (ml/100g) 2.50 2.00 1.50 1.00 0.50 0.00 Early l Typical Late Harvest Point 0.00 Early Typical Late Harvest Point
Cascade Essential Oil Cascade Essential Oil 3.00 2010 Farm I 2011 Farm I 3.00 2010 Farm II 2011 Farm II Essential Oil (ml/100g) 2.50 2.00 1.50 1.00 0.50 Essential Oil (ml/100g) 2.50 2.00 1.50 1.00 0.50 0.00 Early Typical Late Harvest Point 0.00 Early Typical Late Harvest Point Preliminary brewing: Cascade Timing of hop addition and flavor impact! Bitterness a function of alpha and boil time! Aromatic level is a function of volatilization Kettle hop + + Floral Citrus Spicy Resinous Late hop ++ ++ ++ Typical harvest hops = apple, apricot/peach, and sweaty/onion/garlic notes. Late harvest hops = higher melon and floral notes. Dry hop +++ +++ +++ +
Oil quantity and quality Questions?! Maturity influences both! Hop processing influences both " Drying " Pelletizing " Storage conditions! Hop aroma is tied to hop oil Oregon State University