Trevor roberts

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Trevor roberts

  1. 1. Brewing Ingredients Symposium forThe British Guild of Beer Writers Hops & Hop Products Trevor Roberts 28th February 2012
  2. 2. Hops & Hop ProductsInfluences of hops on beer qualityIntroduction to the full range of hop productsDifferent ways of hopping & flavour differentiationThe cost of hops in beerQuestions
  3. 3. The case for Hops & Hop ProductsThe objective....... to convince you that hops are THE brewing rawmaterial that open up many opportunities for thebrewer whilst at the same time representingexcellent value for money!!
  4. 4. Hops & Hop ProductsInfluences of hops on beer qualityIntroduction to the full range of hop productsDifferent ways of hopping & flavour differentiationThe cost of hops in beerQuestions
  5. 5. Typical Analysisof Hops (after Stevens)Resins 15%Proteins 15%Monosaccharides 2%Polyphenols 4%Pectins 2%Volatile Oils 0.5%Ash 8%Moisture 10%Cellulose etc. 43%
  6. 6. Typical Analysisof Hops (after Stevens)Resins 15%Proteins 15%Monosaccharides 2%Polyphenols 4%Pectins 2%Volatile Oils 0.5%Ash 8%Moisture 10%Cellulose etc. 43%
  7. 7. Lupulin Glands
  8. 8. Why Use Hops? PrecipitationBitterness of proteins Biological Aroma Stability Foam Anti-Oxidant
  9. 9. Why Use Hops – Hop Resins? (principally the alpha- and beta-acids) PrecipitationBitterness of proteins Biological Aroma Stability Foam Anti-Oxidant
  10. 10. Hop Resins - Bitterness• Principal hop resins are the alpha acids (non-bittertaste) – converted to iso-alpha-acids (bitter taste)when boiled with the wort by the process ofIsomerisation• Alpha acids not very soluble in wort but iso-alpha-acids more soluble; however the efficiency ofconversion and dissolution in wort is poor - onlyabout 45-55%• Iso-alpha-acids readily stripped out by absorptiononto yeast, protein and filters; final efficiency in beeris only around 30-35% (when using traditional hoppingmethods)
  11. 11. Hop Resins – Contribution to Formation of Beer Foam • Hydrophobicity – Iso-alpha-acids show a tendency to readily come out of solution • Ability to bind proteins – readily form complexes with polypeptides from the beer • Iso-alpha-acid/Polypeptide complexes – provide structural strength to the film layer around the bubbles; helps prevent foam collapse
  12. 12. Hop Resins – Contribution to Foam Lacing• Beer slowly drains from foam• Iso-alpha-acid/Polypeptide complexes get stronger - left behind on surface of glass• >10 mgs/l iso-alpha acids (10 BU’s) required to achieve lacing; >20 mgs/l for optimum effect
  13. 13. Hop Resins – Biological Stability • Use of hops in brewing dates back to medieval times • Introduced into Europe in the 11th century • In due course consequent benefits realised by brewers: - able to brew in the summer months - beers could be shipped long distances without spoilage (IPA to India)
  14. 14. Hop Resins – Biological Stability• Alpha acids, beta acids and iso-alpha-acids - all demonstrate antibacterial activity• Disrupt transport systems across bacterial cell membranes• Known to suppress the development of gram positive bacteria e.g. Acetobacter, Lactobacillus, Pediococcus• Some inhibitory effect against fungi (but fortunately not yeast!!)• Recent work has shown that a minimum of 10 BU’s needed for any effect (previously though to be 18)?• Unhopped or very lowly hopped worts can be vulnerable
  15. 15. Hop Resins – Biological StabilityRecognition of the inhibitory effect of the NATURAL hopresins in many non-brewing applications:•Incorporation into a burn ointment•Use in deodorants•Use in mouthwash and toothpaste•Suppression of Listeria sp. in soft cheeses & otherprocessed food products (hot dogs in the USA!)•Bacterial suppression in sugar beet processing•Control of micro-organisms in distilleries
  16. 16. Why Use Hops – Essential Oils? Precipitation Bitterness of proteins Biological Aroma Stability Foam Anti-Oxidant
  17. 17. Essential Oils – Hop Aroma & CharacterWikipedia defines Essential Oils thus:An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove. An oil is "essential" in the sense that it carries a distinctive scent, or essence, of the plant.
  18. 18. Principal Constituents of Hop Oils ESSENTIAL OILS HYDROCARBON OXYGENATED SULPHUR FRACTION FRACTION FRACTION 50-80% 20-50% <1.0%• Highly volatile • Volatile • Highly volatile• Not very soluble • More soluble •Undesirable•Apparent when •Desirable hop •Sulphury, dirtydry hopping characters aromas 60+ compounds 230+ compounds 30+ compounds
  19. 19. Essential Oils – Hop Aroma & Character• Hop oil analysis (in beer) is difficult and complex (GLC, GLC-MS techniques) – also expensive• Difficult to be precise in which compounds found in beer come from hops (9 definitely) as some of the oxygenated compounds also produced during fermentation• Linalool is one of the easiest to identify and is used as a ‘hoppy’ marker - > 20 µg/l then beer can be said to be ‘hoppy’• Difficult to predict aroma effect in beer from rubbing hops
  20. 20. The Hop Aroma ‘Contradiction’… Hop essential oils largely responsible for the desirable hop aroma in beerBut……….• No one oil component typically “hoppy”• Only a few hop oil compounds are found unchanged in beer (dry hopped beers?)• Normally hop oil components in beer are below their taste thresholds• Additive & synergistic effects
  21. 21. Why Use Hops - Polyphenols? Precipitation Bitterness? of proteins Biological Aroma Stability Foam Anti-OxidantBody, Fullness Flavour Stability Health Benefits?
  22. 22. Hop Polyphenols – Precipitation of Proteins (in wort & beer) Most common causes of Beer Haze: • Residual starch - malting/mashing regimes • Oxalate - calcium deficient worts • β-glucan - poorly modified malts • Carbohydrate & Protein - damaged yeast • Lubricants - from can lids • Dead bacteria - malt • Protein-Polyphenol complexes
  23. 23. Protein-Polyphenol Interaction in Beer (after Siebert)
  24. 24. Hop Polyphenols – Relevance in Protein removal from Beer?• “Only 20-30% of Polyphenols in beer are . derived from hops” (rest from mash tun materials)?• “70% of malt Polyphenols but only 20% of hop-derived Polyphenols survive precipitation as hot & cold break during and after kettle boiling?” (McMurrough et al)• Hop polyphenols have some importance in achieving haze stability in beer by removing large molecular weight proteins
  25. 25. Hop Polyphenols – Anti-oxidants • What are anti-oxidants? Compounds capable of: o Delaying, retarding or preventing oxidation o Reducing the undesirable effects of oxidation• Hop Polyphenols demonstrate good anti-oxidant activity and can therefore be shown to be beneficial in preventing oxidation processes in beer thereby improving flavour stability• Flavour stability of hop pellet brewed beers (containing hop polyphenols) has been shown to be better than CO2 Extract brewed beers (no polyphenols)
  26. 26. Hop Polyphenols – Anti-oxidants• What are anti-oxidants?Compounds capable of:o Delaying, retarding or preventing oxidationo Reducing the undesirable effects of oxidationPossible health benefits? Help to combat dangerousfree radicals in body thereby: educing cardiovascular problems•Fighting the development of cancer•Reducing the incidence of osteoporosis•Slowing up the ageing process (arthritis, strokes,cataracts, alzheimers etc.)
  27. 27. Hop Polyphenols - FlavourContribution to Flavour:•Some polyphenols do add a bitter flavour (sometimesdescribed as astringency)•Has been shown in taste tests that hop polyphenols add‘body’, ‘fullness’ and ‘mouthfeel’ to beer•Compare beers brewed to same bitterness specificationbut using:• Low alpha aroma hop (more weight therefore pro-ratamore polyphenols added)• High alpha hop (less weight therefore pro-rata lesspolyphenols added)•Low alpha aroma hop beers preferred by tasters
  28. 28. Hops & Hop ProductsInfluences of hops on beer qualityIntroduction to the full range of hop productsDifferent ways of hopping & flavour differentiationThe cost of hops in beerQuestions
  29. 29. The Development of Hop Products First commercial, aqueous hop extracts produced in Germany in the1800’s 1850’s followed by petroleum ether (USA, 1870’s) and alcohol extracts (1890’s).1910 - 1930 First hop oil emulsions produced. First aqueous iso-extracts produced in the UK; hop powders and1960’s pellets introduced into Europe. Widespread use of Type 90 and Type 45 pellets; stabilised pellet1970’s patent and early patents on reduced products registered (USA). Liquid and supercritical CO2 extraction processes developed;1980’s increasing use of iso-extracts; iso-pellets patented and fractionated hop essences available. Further reduced product patents registered and the more general use1990’s of reduced products for foam enhancement and light stable beers. Publication of patents for non-brewing uses of hops & hop2000’s components including many potential pharmaceutical uses
  30. 30. The General Benefits of HopProducts over Leaf (or cone) Hops • Increased shelf-life/stability • Increased bulk density/volume reduction • Improved efficiency of bittering (utilisation) • Reduction in chemical residues/heavy metals • Reduced wort (extract) losses • Opportunity for automated dosing systems (labour saving) • Homogeneity • Provide additional quality benefits (see later)
  31. 31. RawHop Products Hops Concentrated Steam Pellets Stabilized Ethanol Pellets Distilled Type 90 Pellets Extract (Type 45) Hop Oils CO2 Hop Isomerized Extract Pellets Xantho- Hop Oil Type 45 or 90 Extract Type Dry Isomerized Kettle Pure Hop Oil Extract (IKE) Spent Type Noble Tannin Xanthohumol Hops Potassium Extract Light Stable Isomerized Kettle Extract Kettle Extract (LSKE) (PIKE) Rho Beta Concentrate Iso Aroma Concentrate Tetra Extract Concentrate Rho Rho Light Stable Iso-Extract 35% 10%Beta 20% 30% Beta Aroma Tetra in PG Extract 10%
  32. 32. Objectives of the ‘Newer’ HopProducts…To add value for the brewer by: • Providing greater efficiency leading to reduced costs – ‘pre-isomerisation’ of alpha-acids to iso-alpha-acids • Providing additional quality benefits compared to ‘traditional’ hop products o Improved foam performance o Light stable
  33. 33. Hop Products – Kettle Added (Usually solid materials or resin extracts)‘Traditional’: - Leaf Hops - bitterness & aroma - Hop Pellets - bitterness & aroma - Hop Extracts - bitterness & aroma‘New’: - Pre-isomerised Pellets – b’ness, aroma & cost saving - Pre-isomerised Extracts – b’ness, aroma & cost saving - Aroma Extracts – aroma only - Light stable Extracts – b’ness, aroma & Light stability
  34. 34. Hop Products – What is meant by ‘Pre-isomerisation’• Isomerisation normally takes place during boiling in the kettle – inefficient (final efficiency in beer 30-40%)• In pre-isomerised products the alpha-acids are isomerised to iso-alpha in the product before the boiling process• Involves optimising the conditions for isomerisation during the hop product production process using: o heat o magnesium salts (naturally present in wort) • Usually achieve 50-60+% efficiency in beer
  35. 35. Hop Products – Post Fermentation Addition (usually aqueous liquids)‘Old’ Technology: - Dry hops – aroma only - Isomerised Extract (PFB) – bitterness only‘New’ Technology: - Reduced Isomerised Extractso Rho (Di-hydro-iso-alpha-acid) – b’ness, Light Stabilityo Tetra (Tetra-hydro-iso-alpha-acid) – b’ness, LS & foamo Hexa (Hexa-hydro-alpha-acid) – b’ness, LS & foam- Hop Oil Products – aroma only
  36. 36. Hop Products – What is meant by ‘Reduced’• Hop products in which the alpha-acid is firstly converted to iso-alpha-acids and then modified by the process of hydrogenation to a ‘reduced’ form• Because the iso-alpha is in a reduced form it is resistant to effects of UV light (i.e. doesn’t split and produce ‘skunky’ flavours) therefore referred to as light stable; can therefore use clear glass bottles• Some of the reduced products are also more foam positive than unreduced iso-alpha-acids. The modified molecular structure encourages even more combination with polypeptides leading to more stable foam.
  37. 37. Hops & Hop ProductsInfluences of hops on beer qualityIntroduction to the full range of hop productsDifferent ways of hopping & flavour differentiationThe cost of hops in beerQuestions
  38. 38. Product Differentiation is a key objective of manylarge, regional and craft brewers for new, seasonalor one-off products. Arguably most typically (and most easily) achieved by use of hops by: • Choice of variety (Paul will hopefully discuss) • Choice of hop product • Time and point of addition
  39. 39. Product Differentiation............. Typically achieved by: • Choice of hop product • whole hop products i.e. those products containing the full range of important hop components – leaf, (iso-) pellets • partially fractionated products i.e. those products with some components removed – CO2 Extract, iso-resin extracts, beta aroma extracts • fractionated products i.e. single component products – hop oil fractions, iso-alpha extract (including reduced iso-extracts)
  40. 40. Product Differentiation.............Typically achieved by:• Time and point of addition o Kettle addition – early or late in the boil [leaf, pellets, extracts & aroma extracts] o Addition into hopback, whirlpool or even fermenter [leaf, (iso-)pellets, (iso-resin-) extracts, aroma extracts & oil fractions] o Addition into RBT, in-line pre-filter or BBT [pellets, (reduced-) iso-extracts, oil fractions] o Addition into container [leaf hops, oil fractions]
  41. 41. Changes in Linalool (μg/l) during Brewing Hop additions Fermentation 1 2 (Pellets) & Maturation 60.0 Linalool micro-grams/litre Whirlpool Beer 50.0 40.0 30.0 20.0 Wort Boiling 10.0 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 Sample No.
  42. 42. Hops & Hop ProductsInfluences of hops on beer qualityIntroduction to the full range of hop productsDifferent ways of hopping & flavour differentiationThe cost of hops in beerQuestions
  43. 43. Cost of a Typical Cask Beer - % Split(Beer – 4% abv; BU – c.25; brewery: 300,000 – 400,000 barrels pa)
  44. 44. Cost of a Typical Cask Beer - % Split(Beer – 4% abv; BU – c.25; brewery: 300,000 – 400,000 barrels pa)
  45. 45. The case for Hops & Hop ProductsSo for around £0.005 - £0.01 per pint the brewercan cost effectively achieve........• Flavour & aroma• Improved haze & flavour stability• Light stability• Improved foam performance• Microbiological protection• Cost savings............... a genuine ‘value-for-money’, flexibleand convenient raw material!!?
  46. 46. I rest my case!Thank you for your attention

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