Formation of colour and flavour compounds in crystal copy
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A presentation looking at the manufacturing process of crystal malt for application in food and beers. Particular focus on the formation of colour and flavour during the production process.
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Formation of colour and flavour compounds in crystal copy
- 1. Formation of Colour and Flavour Compounds in Crystal Malt Ross Turner | PureMalt Products Ltd MBAA Saturday 7th June 2014
- 2. Agenda 1. Introduction to Crystal Malt 2. Crystal Malt Production 3. Maillard Reaction Principles 4. Colour and Flavour Development 5. Quality: ‘Good vs Bad’ Crystal Malt 6. Summary
- 3. Introduction to Crystal Malt • Crystal malt is used in both brewing and food manufacturing • Crystal malt addition to beer typically 1-20% • Utilised for both colour and flavour enhancement • Wide variety of crystal malts available with varying intensities of colour and flavour profiles Crystal Malt Specification: (Typical ranges) Colour: 20-400 EBC Extract: 75-80% Moisture: 4.5-6.5% pH: 4.8-5.2 Probat Roaster
- 4. Introduction to Crystal Malt • Produced from Green Malt • High moisture content >46% • High protein content up to 13% • High germination temperature 20°C • Good homogeneous modification! • Two stage batch production process: • Stewing (Gelatinisation/Saccharifaction) • Roasting (Maillard/Caramelisation) Stage Temperature Time Stewing 60-80°C 20-60mins Roasting 135-180°C 80-100mins 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 MOISTURE% TEMPERATURE TIME (MINS) Temperature Profile: Crystal Malt Production Product Temperature % Moisture Stewing phase Roasting phase
- 5. Crystal Malt Production: Stewing • In-Kernel ‘mashing’ process • Gelatinisation, liquefaction and saccharification takes place • Diastatic & Proteolytic enzyme activity • Starch degradation to sugars • Protein degradation to amino acids • 60-80°C temperature is optimal for enzyme activity • Roasting Drum is sealed to retain moisture • Highly modified Green Malt becomes ‘wort’ equivalent inside kernel! Enzymic activity during stewing Drum Conditions: 60-80°C 20-60mins
- 6. Crystal Malt Production: Roasting • Colour and flavour formation through: • Maillard Reactions • Caramelisation Reactions • Process variables: • Time • ‘Joe’ Factor! (artisanal operator impact) • Temperature • Moisture content • Moisture reduction to 3-4% • Enzyme inactivation Drum Conditions: 135-180°C 80-100mins
- 7. Maillard Reaction Chemistry Amino Acids Reducing sugars Heat Melanoidins & Flavour compounds • Two states of Maillard reactions in crystal malt production • Aqueous reactions (water acts as solvent) • Solid-State (pyrolysis) • Produce different flavour impressions depending on amino acid involved • Accelerated by high protein content malt, high temperatures and low pH.
- 8. Crystal Malt Specifications: Flavour Formation Compound Odour Characteristics Concentration in Crystal Malt Methylpyrazine Popcorn, Nutty, Cocoa 0.10 2- Furaldehyde (furfural) Bread, Almond, Sweet 0.78 Isomaltol Burnt Sugar, Fruity 5.11 2- Furanmethanol Bready, Estery, Sweet 21.0 Maltol Caramel 155 DDMP Candy, Cookies 28.2
- 9. Crystal Malt: Flavour Formation Compound Symbol Methyl-Pyrazine Isomaltol DDMP 2-Furaldehyde 2-Furanmethanol Maltol
- 10. Maillard Reaction: Colour Formation Malt Type Colour (EBC) Colour (Lovibond) Cara 2.5-6.5 1.5-3 Caramalt 25-40 10-15 Premium Caramalt 45-60 17-23 Crystal Light 80-100 30-37 Crystal 130-160 50-60 Crystal Dark 200-230 75-86 Crystal 400 400-440 150-165 Time Temperature
- 11. Good vs Bad Crystal Malt Homogeneous Crystal Malt Un-homogeneous Crystal Malt
- 12. Time Temperature Crystal Malt Sensory Profile 200°C 180°C 160°C 140°C 120°C 100°C 80°C 60°C 40°C 20°C 0°C Candy Cookie/Nutty Toffee Caramel
- 13. Acknowledgements Many thanks to… David Cook Philip Robbins Erika Trauth
- 14. Ross Turner PureMalt Products Ltd. Ross.Turner@PureMalt.com
Editor's Notes
- Stepping in for Ron Duszanskyj, apologise for his absence. (Thanks to the MBAA for the opportunity to talk) (My 1st visit to ‘Brewing Summit’) Excited to be here! IReally enjoyable evening last night!
- Objective of presentation is to present some basic principles associated with the production of crystal malt and to discuss colour and flavour development during the drum roasting process. (Talk through presentation agenda.) (Set expectations about technical knowledge.)
- Addition rate 1-20% in beer Used for colour and flavour addition in a number of beer styles Wide variety of products available from different suppliers with different colour and flavour profiles Typical Ranges: Colour 20-400 EBC (depending on product and degree of roasting) Slight lower extract % than standard pale malt due to use of sugars in colour/flavour development reactions Moisture content slightly higher than standard pale malt pH sometime low due to ‘Green Malt’ providing optimal conditions for lactic growth during malting process with higher germination temperatures (20DegC)
- Feedstock quality: Protein content higher than normal (need amino acids for M/R) Homogenous modification Uniform starch conversion during stewing. Development of Maillard pre-cursors Effects quality and rate of colour/flavour development Roasting Process: Two stage: Stewing: Gelatinisation, liquefaction, saccharification occurs Roasting: Colour and flavour development through maillard, caramelisation and enzymatic browning reactions Discuss graph and explain what is happening.
- “Brewing in the grain”- Essentially the same as the mashing process in a brewery The ‘Stewing’ process occurs between 60-80°C. The temperature conditions utilised are optimal for hydrolytic enzyme activity and the roasting drum is sealed to retain moisture Starch conversion to sugars through diastatic enzyme degradation Protein degradation to amino acids through proteolytic enzyme activity This picture shows a green malt kernel during the ‘stewing’ process; undergoing enzymatic conversion. You can see that the ‘Rub’ reveals a clear sugary liquid that more closely replicates wort than the typical starchy endosperm of a typical malt kernel.
- So we’ve seen that the ‘Stewing’ process delivers the pre-cursors for Maillard reactions Reducing sugars Amino acids Roasting process occurs at 135-180°C Roasting stage process variables that affect product quality and thermal flavour generation: Temperature Time ‘Joe’ Factor! – Mention efforts to ‘engineer out’. Temp/Colour development profiling developed by David Cook in PHD Thesus. “There’s three mechanisms really”: 1) Smoke 2) Cuppa Tea 3) Smoke and Cuppa Tea Moisture content of green malt: High MC% = more flavour less colour! (Water is a participant of flavour formation M/R pathways) Barley variety and quality/parameters used during malting process Important to reduce moisture content to 3-4% for safe storage (as with standard pale malts)
- Maillard Reactions are the main source of colour and flavour development in the crystal malt roasting process. Two reaction states: Aqueous: Water acts as solvent to produce more flavour-active compounds that associate with ‘boiled’ foodstuffs Solid-State (Pyrolytic): Faster reaction that the aqueous state. Produces higher colour formation and more roasted flavour compounds. Maillard Reactions occur as a result of present amino acids and reducing sugars reacting with heat as the catalyst. Producing Melanoidins (colouring pigments) and flavour compounds. Maillard reactions are accelerated by High protein content barley varieties High temperatures during roasting Low pH of green malt feedstock. (particularly with German styles of crystal malts)
- Crystal malts contain the largest range of flavour compounds of any of the ‘speciality malts’ due to the complex Maillard pathways utilised during the roasting process. Falvour development is dependent on up-stream variables and is a result of complex maillard pathways Barley variety: Will have different amino acid spectrums that result in different maillard flavour products Protein content: Protein content will dictate concentration of amino acids available as maillard reaction pre-cursors Moisture content: High moisture content will generally act as a solvent during maillard process and encourage flavour development over colour Malting conditions: Homogenous modification will obviously tie into the above
- Graph results are solvent extraction/GC-MS analysis. (Gas Chromatography/Mass Spectrometry. Graph shows the development of the previously mentioned flavour compounds during the roasting process. Important to notice that flavour development is not linear and the concentrations of the different flavour compounds will vary dependant on a plethora of variables from barley variety through to malting and roasting conditions (some of which we have discussed) Good to note that some of the flavour compounds show a higher rate of formation during the higher moisture stewing phase (such as 2-Furanmethanol which produces bready or estery flavours. and some during the much lower moisture roasting phase. For example Maltol (Caramel) Point out initial drop in flavour development is a result of venting the drum and the flavour concentrations dropping as a result of their volatility. 2nd Drop due to casting the crystal malt from the drum into the cooling trough. Again flavour compounds lost as a result of volatility.
- As discussed colour development happening during roasting phase as a result of increased temperature and M/R pre-cursor development Colour intensity develops in a short window toward the end of the 120min roasting phase Typically occurs as the moisture content falls There are a wide variety of crystal malt products available on the market place with each malt supplier selecting the optimal colour band for their product
- Compare the two farinator samples shown. The homogeneous sample on the left Good crystal sample Nicely uniform cut 100% of kernels showing a dark red crystalline structure. Made from homogeneously modified malt. When used in a mash bill/grist recipe this sample will yield good extractable colour and flavour into the wort. The Un-homogeneous sample to the right Less uniform cut with multiple kernels appearing white and starchy. Made with poorly modified malt Will yield less colour and flavour during mashing. Possible causes: Poor modification during malting: Poor germinative energy (Dormancy), Poor malting conditions (i.e. inadequate steeping moisture degree) Moisture content losses during ‘stewing’ process: Reduces enzymatic conversion of starch>sugars during ‘Stewing’ which results in no reduced sugars and amino acids for maillard reaction process.
- Flavour and Colour development dependent on: Good quality, homogeneously modified ‘Green malt’ supply. Control of time, temperature and moisture during Stewing/Roasting phases Flavour and colour development is not linear and varies throughout the process (hence ‘Joe’ Factor!) Wide variety of crystal malt products available on the market with a range of colour and flavour profiles. Good quality crystal can make a significant difference to the flavour composition of your beers!!
- I would like to acknowledge and thank: David Cook Philip Robbins Erika Trauth A lot of the content and theory of this presentation was sourced from papers and theses published by these domain experts
- Thank You! I wish you all a fruitful and informative conference and look forward to sharing discussion over beers!