Trevor roberts

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