Flavours Imparted Through Brewing with Roasted Malt Products

Flavours imparted through brewing with roasted malt products

David Cook1*, Susan Clegg1, Qian Yang1, & Irina Bolat2. 1 University of Nottingham, International Centre for Brewing Science, Nottingham, UK 2Boortmalt plc, Zandvoort 2, Haven 350, Bus 1, 2030 Antwerp, Belgium Context • Roasted malt products are used at differing grist percentages to provide colour and flavour to a variety of beer styles. • Prior studies1-3 have reported the flavour properties of the malts themselves; much less is known about the precise flavours imparted to finished beer – how these are modified by the brewing process (e.g. through oxidation, losses to waste streams etc.) – possibility of bio-transformation by yeast to generate novel flavours post- fermentation. • The present study incorporated roasted malts at high grist percentages (8-20%) into a lager base beer, such that the resultant beers could be subjected to sensory analysis to identify the flavours contributed. Roasted malt processing

• Manufactured in drum roasters (below) – High process temperatures, up to the point at which barley/malt will ignite (e.g. max temp. 230 °C) – Drum can be sealed at lower temperatures as in ‘stewing’ of crystal malts and opened to allow drying down to finishing temperatures. • Small batch sizes (e.g. 2 tonnes) ‘Families’ of roasted malt products

Raw barley ‘Pale’ kilned Steep + germinate ‘Green’ Malt or cereals (end of germination) KILNING Malt

DRUM ROASTER DRUM ROASTER DRUM ROASTER (with stewing)

Roasted Barley Light Caramel malts Amber malts (50-75 °EBC) (1200-1550 °EBC) (20 °EBC) Brown malts (90-180 °EBC) Caramalt (28-36 °EBC) Chocolate malts Crystal malts (60-250°EBC) (500-1300 °EBC) Dark Crystal malts Black malts (1200-1550 °EBC) (300-500 °EBC)

During stewing the endosperm contents ‘liquefy’ and on cooling this solidifies into a semi-crystalline/ glassy mass. Colour and flavour formation pathways

Pyrolysis/ Maillard chemistry Caramelisation thermal (reducing sugar + of sugars degradation amino compound →→…..) Lipid oxidation

Key variables: From melanoidins and caramelised time/temperature, sugars moisture content, pH

Complex variety of flavours can be generated dependant on processing 6 Towards a sensory lexicon for malt and roasted products

• There is not an internationally agreed ‘lexicon’ (vocabulary) for describing the sensory properties of malts and roasted products. – Unlike beer which has an accepted flavour wheel with defined terminology, descriptors and flavour standards.

• Some manufacturers have developed and published their own flavour wheels.

• Various published methods4 for sensory evaluation of products: – e.g. Murray et al. (1999). Sensory Analysis of Malt, Tech. Q. Master Brew. Assoc. Am., 1999, 36(1), 15-19. 7 Present research

• Aim: Identify the sensory characteristics imparted to beer by roasted products. – How do these differ from the sensory properties of the roasted products themselves? • Approach: 1. Generate a sensory lexicon for roasted products and use it to define the sensory properties of the family of barley roasted products. 2. Brew lager beers incorporating high proportions of individual roasted products. 3. Generate a sensory lexicon for roasted product lager beers and use it to rate and differentiate the above beers 4. Compare sensory lexicons for roasted products versus the corresponding lager beers. Sensory Analysis of roasted malts Sensory Analysis Process

Lexicon Development – Terms initially generated independently by panellists. – Similar terms grouped and list refined by use of ‘Check all that apply’ (CATA) data and group discussion. Attribute Scale Training – Attributes ranked independently by panellists followed by group discussion of data generated. – Low and high scale points anchored using external references, where required, and group discussion to agree attribute levels. Pre-Assessment – Assessment protocol checked – Data generated used as final verification of panellist scale training. Final Assessment – Carried out in multiple sessions – Final data checked for panellist repeatability and panel agreement. Sample Preparation/ presentation • Samples presented as malt ‘porridge’ – Roasted malts microwaved for 40 s in 13 g batches (850 W domestic microwave) – 35 g ground malt + 65 g water – 5 g of paste presented in sample pot Final Assessment

• 9 roasted products: Caramalt Dark Crystal Malt Chocolate Malt (EBC 18-36) (EBC 380-500) (EBC 800-1000) Light Crystal Malt Amber Malt Black Malt (EBC 80-120) (EBC 50-75) (EBC 1200-1550) Medium Crystal Malt Pale Chocolate Malt Roasted Barley (EBC 130-220) (EBC 460-560) (EBC 1200-1550)

• Final assessment (n=9 panellists) in triplicate over separate sessions. - Malt samples presented under red light - Aroma and Flavour assessed independently. - Attributes scored 0-10 on a linear scale. Mean rating Scores: Aroma of roasted malts (ANOVA/Tukey)

No. Caramalt Crystal malts Amber Chocolate Black Roasted ANOVA Malt Malt Barley groups Light Med. Dark Pale Std. Biscuit 5 5.05b 4.84b 3.40c 1.78d 6.64a 0.28e 0.13e 0.09e 0.20e Burnt 3 0.08a 0.15a 0.19a 0.56a 0.05a 7.14bc 6.99b 7.90c 6.82b Caramel 2 1.34a 1.72a 1.26a 1.48a 1.25a 0.24b 0.10b 0.13b 0.11b Coffee 3 0.10a 0.13a 0.23a 0.23a 0.10a 6.15b 6.29bc 6.93c 5.98b Dk Choc 2 0.21a 0.07a 0.43a 0.29a 0.06a 1.25b 0.90b 1.05b 0.93b Malt loaf 4 4.01b 3.83b 4.99a 5.61a 1.64c 0.43d 0.16d 0.07d 0.11d Malty 4 4.57bc 5.11b 3.73c 3.85c 6.54a 0.43d 0.21d 0.16d 0.20d Nutty 1 0.42a 0.29a 0.29a 0.26a 0.38a 0.14a 0.19a 0.14a 0.14a Smokey 2 0.06a 0.04a 0.04a 0.07a 0.04a 5.97b 6.45b 6.72b 6.07b Sweet 2 2.14a 2.18a 2.43a 2.49a 1.92a 0.53b 0.35b 0.26b 0.32b Treacle 4 1.08ab 0.98ab 2.17cd 2.93d 0.39a 1.62bc 1.18abc 0.99ab 1.59bc Wheaty 4 3.94ab 3.94ab 2.24c 1.89c 4.98a 0.20d 0.13d 0.16d 0.17d

abcde: sample with different letter codes in a row are significantly different (P<0.05) Cluster analysis - aroma

Dendrogram 16 14 12 10 8

6 Dissimilarity 4 2

Choc

Black

Amber

RoastB

Caramalt

PaleChoc

DKCrystal

LightCrystal MedCrystal Cluster Characteristics - Odour

Biscuit/ malty/ Burnt/Coffee/ Maltloaf/malty Wheaty Smoky 8.0 Biscuit 7.0 Burnt Caramel 6.0 Coffee 5.0 DKchoc 4.0 Maltloaf Malty 3.0 Nutty 2.0 Smoky 1.0 Sweet Treacle 0.0 1 2 3 Wheaty Amber Black Dark Crystal Caramalt Chocolate MedCrystal LightCrystal Pale Choc Roasted Barley Mean rating Scores: In-mouth flavour of roasted malts (ANOVA/Tukey) No. of Caramalt Crystal malts Amber Chocolate Black Roasted ANOVA Malt Malt Barley groups Light Med. Dark Pale Std. Astringent 3 2.71a 3.00a 3.67a 4.06ab 3.95a 5.45c 5.80c 5.31bc 5.83c Sour 3 1.98a 1.44a 2.71ab 3.69abc 2.16a 5.23c 4.80bc 4.89bc 5.89c Bitter 2 1.41a 1.34a 3.08ab 3.71b 0.94a 2.95b 3.13ab 3.03ab 4.29b Biscuit 4 4.31b 4.99ab 2.92c 2.0c 5.82a 0.13d 0.10d 0.14d 0.13d Burnt 3 0.13a 0.19a 0.52a 1.43b 0.28a 8.00c 7.81c 8.09c 8.54c Caramel 2 0.96a 1.30a 1.09a 1.04a 0.93a 0.10b 0.06b 0.09b 0.07b Coffee 2 0.16a 0.14a 0.49a 0.50a 0.21a 5.61b 5.95b 5.81b 5.89b Maltloaf 5 2.47c 2.98cd 3.81a 3.51ab 1.11d 0.16e 0.07e 0.10e 0.05e Malty 4 3.15c 4.15ab 3.41bc 2.59c 4.87a 0.10d 0.08d 0.08d 0.01d Smoky 3 0.05a 0.10ab 0.26ab 0.77b 0.09ab 7.67c 8.00c 7.93c 8.21c Sweet 4 1.51bc 2.50a 1.52bc 1.97ab 1.14bc 0.24d 0.11d 0.17d 0.09d Wheaty 5 3.70bc 4.20b 3.40c 2.64d 4.90a 0.07e 0.07e 0.07e 0.09e abcde: sample with different letter codes in a row are significantly different (P<0.05) Cluster Characteristics: In-mouth flavour of roasted malts

Biscuit/ malty/ Burnt/Coffee/ Maltloaf/ Wheaty Smoky/ Astringent Astringent 9.0 Astringent/Sour sour 8.0 bitter 7.0 biscuit Burnt 6.0 Caramel 5.0 Coffee 4.0 Maltloaf 3.0 Malty 2.0 Smoky 1.0 Sweet 0.0 Wheatty 1 2 3 Amber Black malt Dark Crystal Caramalt Chocolate Med. Crystal Light Crystal Pale Chocolate Roasted Barley Roasted Malt Trial beers: Brewing

• A selection of roasted malts were chosen for the brewing trials which covered the spectrum of sensory characteristics identified in the samples. • Beers were brewed at 40 L scale on the University nanobrewery. • pale lager base malt. 5 BU. • same processing for all trial beers with the exception of the incorporation of the roasted malts.

Brew % Roasted malt in grist 40 L University Briggs Brewline Lager (Control) 0 Amber 20 Medium Crystal 20 Chocolate 8 Black 8 Beer finishing and analytical parameters

• Fermentation was carried out with a lager yeast (Saflager S-23). - 20°C x 7 d primary fermentation; 4ºC x 4 d maturation

• Beers conditioned in bottle (500 mL brown PET) with the addition of 3 g dextrose, for 3 weeks (20°C) before being stored refrigerated prior to sensory evaluation.

Brew % Roasted malt in % ABV PG grist Lager (Control) 0 4.32 1.0076 Amber 20 3.76 1.0086 Medium Crystal 20 3.82 1.0104 Chocolate 8 3.89 1.0088 Black 8 3.66 1.0111 Panel details & Sample Presentation

• The panel consisted of 8 members of the University trained beer panel. • All had previously taken part in the coloured malt sensory study. • The beer samples (40 mL) were presented in small amber sample bottles.

Water and crackers used as palate cleansers. Aroma & Flavour Lexicons for roasted malt beers

Aroma Flavour (in-mouth) CATEGORY DESCRIPTORS CATEGORY Descriptor BURNT Burnt / Charcoal / Acrid / Tar / BITTER Bitter Creosote CEREAL Malt / Biscuit / Horlicks BURNT Burnt / Charcoal / Acrid / Tar / Creosote COFFEE Coffee / Roasted Coffee / CEREAL Malt / Biscuit /Horlicks / Wheat Coffee Grounds / Dark COFFEE Coffee / Black Coffee / Dark Chocolate Chocolate FRUITY Dried Mixed Fruit FRUITY Dried Mixed Fruit / Sweet MEDICINAL Soap / Medicinal / Pungent MEDICINAL Soapy / Medicinal / Pungent SMOKY Smoky / Ashtray / Tobacco MUSTY Musty / Cardboard / Papery SOUR Vinegar / Wine / Tangy / Cider SMOKY Smoky / Cigarettes / Ashtrays / SULPHURY Cooked Vegetables / DMS / Sweetcorn Tobacco / Peaty SOUR Vinegar / Sour Milk / Wine SWEET Sweet THICKNESS Thin to Thick / Mouth-Coating SULPHURY Cooked Vegetables / DMS / (Mouthfeel) Sweetcorn ASTRINGENCY Astringent / Dryness in mouth TREACLE Bonfire Toffee / Dark Toffee / (Mouthfeel) Dark Treacle / Liquorice LINGERING Duration / Intensity of Aftertaste (Aftertaste) Comparison of Coloured Malt & Malt Beer Lexicons

Aroma Flavour Mean rating Scores: Aroma of roasted malt beers (ANOVA/Tukey)

Control Crystal Amber Chocolate Black Lager Beer malt beer Malt Beer Malt Beer Malt Beer Fruity 3.60a 4.93a 3.31a 3.12a 3.33a Medicinal 2.21a 2.80a 2.36a 1.40a 1.04a Smokey*** 0.81b 1.98b 1.68b 5.25a 4.90a Sulphury*** 2.92ab 3.73a 4.16a 1.00c 1.45bc Sour*** 3.40a 2.76ab 3.19a 1.49bc 1.13c Coffee*** 0.70b 1.98b 0.94b 4.95a 4.39a Cereal** 2.95a 1.40b 2.70a 1.23b 1.93ab Burnt*** 0.98b 1.50b 1.34b 5.07a 4.08a Treacle*** 0.52b 1.84b 0.80b 4.05a 3.80a Musty*** 3.90a 2.52ab 4.02a 2.02b 1.30b

** P<0.05; ***P<0.01. abcde: sample with different letter codes in a row are significantly different Aroma average sensory data: spider plot

Aroma - Average Data: Scale 0-6

BURNT 6

TREACLE 5 CEREAL

Amber Malt Beer 4

3 Crystal Malt Beer SULPHURY 2 COFFEE 1

Black Malt Beer 0

Chocolate Malt Beer SOUR FRUITY

Lager Malt Beer SMOKY MEDICINAL

MUSTY Principal Components Analysis (PCA 1&2) Aroma

3 CEREAL

Lager Malt MUSTY

(16.50%) Beer 1 Black Malt Amber Malt BeerSOUR BURNT Beer Chocolate 0 SMOKY -3 -2 -1 0 1 COFFEE2 3 Malt Beer4 SULPHURY TREACLE -1 MEDICINAL

-2 Principal component 2 2 component Principal Crystal Malt Beer

FRUITY -3

-4 Principal component 1 (79.21%) Mean rating Scores: In-mouth flavour of roasted malt beers (ANOVA/Tukey)

Control Crystal Amber Chocolate Black Lager Beer malt beer Malt Beer Malt Beer Malt Beer Astringent Mouthfeel** 5.24ab 4.45b 6.03ab 6.20a 6.09a Bitter*** 5.87a 4.37b 5.52ab 6.56a 5.92a Sour** 4.79ab 4.11b 5.68a 4.73ab 4.15b Sweet 2.09a 2.59a 1.60a 2.00a 1.95a Burnt*** 2.21b 1.98b 3.31b 6.19a 6.19a Fruity** 3.39ab 4.53a 3.31ab 2.85b 3.38ab Smokey*** 2.03b 2.04b 3.0b 6.10a 5.95a Sulphury** 2.08ab 2.33a 2.46a 1.54ab 0.72b Medicinal 1.86a 1.83a 2.58a 1.62a 1.42a Cereal*** 2.49a 2.16ab 1.99ab 1.39bc 1.03c Coffee*** 1.20b 1.28b 1.37b 4.28a 4.71a Thickness (mouthfeel)*** 3.73bc 3.53bc 3.18c 5.01ab 5.41a Lingering (mouthfeel)*** 5.81ab 4.67b 6.61a 6.82a 6.92a

** P<0.05; ***P<0.01. abcde: sample with different letter codes in a row are significantly different In-mouth Flavour average sensory data: spider plot

ASTRINGENCY (Mouthfeel) 7 LINGERING (Mouthfeel) BITTER 6 5 THICKNESS (Mouthfeel) 4 BURNT 3 2 SWEET 1 CEREAL 0

SULPHURY COFFEE

SOUR FRUITY SMOKY MEDICINAL

Amber Malt Beer Crystal Malt Beer Black Malt Beer

Chocolate Malt Beer Lager Malt Beer PCA (1&2) Flavour & Mouthfeel

4 SOUR Amber Malt Beer 3 MEDICINAL

2 ASTRINGENCY (Mouthfeel) SULPHURY

LINGERING (Mouthfeel) (29.00%)

2 2 CEREAL 1 BITTER Lager Malt Beer Chocolate Malt … 0 -4 -3 -2 -1 0 1 2 BURNT3 4 SMOKY -1 Black Malt COFFEE compomnent Beer FRUITY -2 THICKNESS (Mouthfeel) Crystal Malt SWEET Principal Beer -3

-4 Principal component 1 (64.52%) Conclusions (1)

• Some highly intense flavour characters transferred from the roasted products into finished beers to impart similar characteristics as in the raw material – e.g. burnt, coffee, smokey • Other flavour characteristics were more subtle (even at 8% and 20% inclusion rates) and were not retained in the finished beer lexicon – e.g. nutty, biscuit, malt loaf • Novel flavours in the finished beer lexicon were most likely derived from the process (Brewhouse/ fermentation) – e.g. fruity, sulfury • Some novel flavours (e.g. medicinal) might be formed by biotransformation of roasted malt flavour compounds by yeast (although not the focus of the present study). Conclusions (2)

• Adjustment of mouthfeel resulted when brewing with roasted malts. – Astringent/ lingering (amber, chocolate and black malts). – Thickness (black malt, chocolate malt). • Adjustment of taste when brewing with roasted malts can influence the flavour perception of characteristics (taste- aroma interactions). – e.g amber malt (+sour), crystal (+sweet), chocolate (+bitter) – Sweet/fruity interactions? Bitter/coffee? • More studies of this kind are needed to better understand the origins of these effects. References

1. Blenkinsop, P. (1991). "The manufacture, characteristics and uses of speciality malts." Tech. Q. Master Brew. Assoc. Am. 28: 145-149. 2. Briggs, D.E. (1998). Malts and Malting. Blackie Academic Press, London, UK. 3. Gretenhart, K. E. (1997). "Speciality malts." Tech. Q. Master Brew. Assoc. Am. 34: 102- 106. 4. Gruber, M. A. (2001). "The flavor contributions of kilned and roasted products to finished beer styles." Tech. Q. Master Brew. Assoc. Am. 38: 227-233. 5. Murray, J.P., Bennett, S.J.E., Chandra, G.S., Davies, N.L. and Pickles, J.L. (1999), “Sensory Analysis of Malt”, Tech. Q. Master Brew. Assoc. Am.,, 36(1), 15-19 Thank you for your attention…….Questions?

We gratefully acknowledge Boortmalt and the University of Nottingham for funding this research.

With thanks to my co-authors, Sue and Candy, for conducting this piece of original research. e-mail: [email protected]