trevor roberts
Post on 22-Oct-2014
705 views
DESCRIPTION
TRANSCRIPT
Brewing Ingredients Symposium
forThe British Guild of Beer
WritersHops & Hop Products
Trevor Roberts
28th February 2012
Hops & Hop Products
Questions
The cost of hops in beer
Different ways of hopping & flavour differentiation
Introduction to the full range of hop products
Influences of hops on beer quality
The case for Hops & Hop Products
The objective....
... to convince you that hops are THE brewing raw material that open up many opportunities for the brewer whilst at the same time representing excellent value for money!!
Hops & Hop Products
Questions
The cost of hops in beer
Different ways of hopping & flavour differentiation
Introduction to the full range of hop products
Influences of hops on beer quality
Typical Analysis of Hops (after Stevens)Resins 15%
Proteins 15%
Monosaccharides 2%
Polyphenols 4%
Pectins 2%
Volatile Oils 0.5%
Ash 8%
Moisture 10%
Cellulose etc. 43%
Typical Analysis of Hops (after Stevens)Resins 15%
Proteins 15%
Monosaccharides 2%
Polyphenols 4%
Pectins 2%
Volatile Oils 0.5%
Ash 8%
Moisture 10%
Cellulose etc. 43%
Lupulin Glands
Why Use Hops?
Precipitationof proteins
BiologicalStability
Anti-OxidantFoam
Bitterness
Aroma
Why Use Hops – Hop Resins?
(principally the alpha- and beta-acids)
Precipitationof proteins
Precipitationof proteins
BiologicalStability
Anti-OxidantAnti-OxidantFoam
Bitterness
AromaAroma
Hop Resins - Bitterness• Principal hop resins are the alpha acids (non-bitter taste) – converted to iso-alpha-acids (bitter taste) when boiled with the wort by the process of Isomerisation
• Alpha acids not very soluble in wort but iso-alpha- acids more soluble; however the efficiency of conversion and dissolution in wort is poor - only about 45-55%
• Iso-alpha-acids readily stripped out by absorption onto yeast, protein and filters; final efficiency in beer is only around 30-35% (when using traditional hopping methods)
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
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
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)
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
Hop Resins – Biological Stability
Recognition of the inhibitory effect of the NATURAL hop resins 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 & other processed food products (hot dogs in the USA!)•Bacterial suppression in sugar beet processing•Control of micro-organisms in distilleries
Why Use Hops – Essential Oils?
Precipitationof proteins
Precipitationof proteins
BiologicalStability
BiologicalStability
Anti-OxidantAnti-OxidantFoamFoam
BitternessBitterness
Aroma
Wikipedia 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.
Essential Oils – Hop Aroma & Character
Principal Constituents of Hop Oils
ESSENTIAL OILS
HYDROCARBON OXYGENATED SULPHUR
FRACTION FRACTION FRACTION
50-80% 20-50% <1.0%
• Highly volatile
• Not very soluble
•Apparent when dry hopping
• Volatile
• More soluble
•Desirable hop characters
• Highly volatile
•Undesirable
•Sulphury, dirty aromas
60+ compounds 230+ compounds 30+ compounds
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
The Hop Aroma ‘Contradiction’…Hop essential oils largely responsible for the
desirable hop aroma in beer
But……….• 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
Why Use Hops - Polyphenols?
Precipitationof proteins
BiologicalStability
BiologicalStability
Anti-OxidantFoamFoam
AromaAroma
Flavour Stability
Health Benefits?
Bitterness?
Body, Fullness
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
Protein-Polyphenol Interaction in Beer (after Siebert)
.
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
Hop Polyphenols – Anti-oxidants • What are anti-oxidants?
Compounds capable of:o Delaying, retarding or preventing oxidationo 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)
Hop Polyphenols – Anti-oxidants
Possible health benefits? Help to combat dangerous free radicals in body thereby:• Reducing cardiovascular problems•Fighting the development of cancer•Reducing the incidence of osteoporosis•Slowing up the ageing process (arthritis, strokes, cataracts, alzheimers etc.)
• What are anti-oxidants?
Compounds capable of:
o Delaying, retarding or preventing oxidation
o Reducing the undesirable effects of oxidation
Hop Polyphenols - FlavourContribution to Flavour:•Some polyphenols do add a bitter flavour (sometimes described as astringency)•Has been shown in taste tests that hop polyphenols add ‘body’, ‘fullness’ and ‘mouthfeel’ to beer•Compare beers brewed to same bitterness specification but using:
1. Low alpha aroma hop (more weight therefore pro-rata more polyphenols added)
2. High alpha hop (less weight therefore pro-rata less polyphenols added)•Low alpha aroma hop beers preferred by tasters
Hops & Hop Products
Questions
The cost of hops in beer
Different ways of hopping & flavour differentiation
Introduction to the full range of hop products
Influences of hops on beer quality
The Development of Hop Products
1800’s First commercial, aqueous hop extracts produced in Germany in the 1850’s followed by petroleum ether (USA, 1870’s) and alcohol extracts (1890’s).
1910 - 1930 First hop oil emulsions produced.
1960’s First aqueous iso-extracts produced in the UK; hop powders and pellets introduced into Europe.
1970’s Widespread use of Type 90 and Type 45 pellets; stabilised pellet patent and early patents on reduced products registered (USA).
1980’s Liquid and supercritical CO2 extraction processes developed; increasing use of iso-extracts; iso-pellets patented and fractionated hop essences available.
1990’s Further reduced product patents registered and the more general use of reduced products for foam enhancement and light stable beers.
2000’s Publication of patents for non-brewing uses of hops & hop components including many potential pharmaceutical uses
The General Benefits of Hop Products 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)
RawHops
Concentrated Pellets
(Type 45)
Ethanol Extract
CO2 Hop Extract
Steam Distilled Hop Oils
Hop Oil Type Dry
Isomerized Kettle
Extract (IKE)
Rho Concentrate
Xantho-Extract
Pure Xanthohumol
Stabilized Pellets
Isomerized Pellets
Type 45 or 90
Beta Aroma Extract
Light Stable Beta Aroma
Extract
Beta 20% in PG
Light Stable Kettle Extract
(LSKE)
Tannin Extract
IsoConcentrate
Rho 35%
Tetra Concentrate
Tetra 10%
Spent Hops
Potassium Isomerized
Kettle Extract (PIKE)
Hop Oil Type Noble
Pellets Type 90
Iso-Extract30%
Rho10%
Hop Products
• Providing greater efficiency leading to reduced costs – ‘pre-isomerisation’ of alpha-acids to iso-alpha-acids
• Providing additional quality benefits compared to ‘traditional’ hop productso Improved foam performanceo Light stable
Objectives of the ‘Newer’ Hop Products…
To add value for the brewer by:
‘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
Hop Products – Kettle Added(Usually solid materials or resin
extracts)
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
‘Old’ Technology:
- Dry hops – aroma only
- Isomerised Extract (PFB) – bitterness only
‘New’ Technology:
- Reduced Isomerised Extracts
o Rho (Di-hydro-iso-alpha-acid) – b’ness, Light Stability
o Tetra (Tetra-hydro-iso-alpha-acid) – b’ness, LS & foam
o Hexa (Hexa-hydro-alpha-acid) – b’ness, LS & foam
- Hop Oil Products – aroma only
Hop Products – Post Fermentation
Addition (usually aqueous liquids)
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.
Hops & Hop Products
Questions
The cost of hops in beer
Different ways of hopping & flavour differentiation
Introduction to the full range of hop products
Influences of hops on beer quality
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
Product Differentiation is a key objective of many large, regional and craft brewers for new, seasonal or one-off products.
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)
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]
Product Differentiation.............
Changes in Linalool (μg/l) during Brewing
0.0
10.0
20.0
30.0
40.0
50.0
60.0
1 2 3 4 5 6 7 8 9 10 11 12 13
Sample No.
Lin
alo
ol
mic
ro-g
ram
s/l
itre
Wort Boiling
Whirlpool Beer
Fermentation & Maturation
Hop additions
(Pellets)1 2
Hops & Hop Products
Questions
The cost of hops in beer
Different ways of hopping & flavour differentiation
Introduction to the full range of hop products
Influences of hops on beer quality
Cost of a Typical Cask Beer - % Split
(Beer – 4% abv; BU – c.25; brewery: 300,000 – 400,000 barrels pa)
Cost of a Typical Cask Beer - % Split
(Beer – 4% abv; BU – c.25; brewery: 300,000 – 400,000 barrels pa)
The case for Hops & Hop ProductsSo for around £0.005 - £0.01 per pint the brewer
can cost effectively achieve........• Flavour & aroma• Improved haze & flavour stability• Light stability • Improved foam performance• Microbiological protection• Cost savings
............... a genuine ‘value-for-money’, flexible and convenient raw material!!?
I rest my case!Thank you for your attention