Brewing Science and practice Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC Published by Woodhead Publishing Limited, Abington Hall, Abington Cambridge CB1 6AH, England www.woodhead-publishing.com Published in North America by CRC Press LLC, 2000 Corporate Blvd, NW Boca Raton FL 33431, USA First published 2004, Woodhead Publishing Limited and CRC Press LLC � 2004, Dennis E. Briggs, Chris A. Boulton, Peter A. Brookes and Roger Stevens The authors have asserted their moral rights. This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. Reasonable efforts have been made to publish reliable data and information, but the authors and the publishers cannot assume responsibility for the validity of all materials. 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Project managed by Macfarlane Production Services, Markyate, St Albans, Hertfordshire (e-mail: Contents Preface 1 An outline of brewing 1.1 Introduction 1.2 Malts 1.3 Mash tun adjuncts 1.4 Brewing liquor 1.5 Milling and mashing in 1.6 Mashing and wort separation systems 1.7 The hop-boil and copper adjuncts 1.8 Wort clarification, cooling and aeration 1.9 Fermentation 1.10 The processing of beer 1.11 Types of beer 1.12 Analytical systems 1.13 The economics of brewing 1.14 Excise 1.15 References and further reading 1.15.1 The systems of malting and brewing analysis 1.15.2 General references 2 Malts, adjuncts and supplementary enzymes 2.1 Grists and other sources of extract 2.2 Malting 2.2.1 Malting in outline 2.2.2 Changes occurring in malting grain 2.2.3 Malting technology 2.2.4 Malt analyses 2.2.5 Types of kilned malt 2.2.6 Special malts Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC vi Contents 2.2.7 Malt specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3 Adjuncts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2.3.1 Mash tun adjuncts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2.3.2 Copper adjuncts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 2.4 Priming sugars, caramels, malt colourants and Farbebier . . . . . . . . . . 45 2.5 Supplementary enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 3 Water, effluents and wastes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.2 Sources of water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.3 Preliminary water treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.4 Secondary water treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 3.5 Grades of water used in breweries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 3.6 The effects of ions on the brewing process . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.7 Brewery effluents, wastes and by-products . . . . . . . . . . . . . . . . . . . . . . . . . 68 3.7.1 The characterization of waste water . . . . . . . . . . . . . . . . . . . . . . . . 69 3.7.2 The characteristics of some brewery wastes and by-products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 3.8 The disposal of brewery effluents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.8.1 Preliminary treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.8.2 Aerobic treatments of brewery effluents . . . . . . . . . . . . . . . . . . . 75 3.8.3 Sludge treatments and disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 3.8.4 Anaerobic and mixed treatments of brewery effluents . . . . . 79 3.9 Other water treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 3.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 4 The science of mashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 4.2 Mashing schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 4.3 Altering mashing conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.3.1 The grist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 4.3.2 Malts in mashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 4.3.3 Mashing with adjuncts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4.3.4 The influence of mashing temperatures and times on wort quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 4.3.5 Non-malt enzymes in mashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 4.3.6 Mashing liquor and mash pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.3.7 Mash thickness, extract yield and wort quality . . . . . . . . . . . . . 116 4.3.8 Wort separation and sparging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 4.4 Mashing biochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 4.4.1 Wort carbohydrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 4.4.2 Starch degradation in mashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 4.4.3 Non-starch polysaccharides in mashing . . . . . . . . . . . . . . . . . . . . 136 4.4.4 Proteins, peptides and amino acids . . . . . . . . . . . . . . . . . . . . . . . . . 142 4.4.5 Nucleic acids and related substances . . . . . . . . . . . . . . . . . . . . . . . 146 4.4.6 Miscellaneous substances containing nitrogen . . . . . . . . . . . . . . 146 4.4.7 Vitamins and yeast growth factors . . . . . . . . . . . . . . . . . . . . . . . . . 149 4.4.8 Lipids in mashing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC 4.4.9 Phenols 4.4.10 Miscellaneous acids 4.4.11 Inorganic ions in sweet wort 4.5 Mashing and beer flavour 4.6 Spent grains 4.7 References 5 The preparation of grists 5.1 Intake, handling and storage of raw materials 5.2 The principles of milling 5.3 Laboratory mills 5.4 Dry roller milling 5.5 Impact mills 5.6 Conditioned dry milling 5.7 Spray steep roller milling 5.8 Steep conditioning 5.9 Milling under water 5.10 Grist cases 5.11 References 6 Mashing technology 6.1 Introduction 6.2 Mashing in 6.3 The mash tun 6.3.1 Construction 6.3.2 Mash tun operations 6.4 Mashing vessels for decoction, double mashing and temperature- programmed infusion mashing systems 6.4.1 Decoction and double mashing 6.4.2 Temperature-programmed infusion mashing 6.5 Lauter tuns 6.6 The Strainmaster 6.7 Mash filters 6.8 The choice of mashing and wort separation systems 6.9 Other methods of wort separation and mashing 6.10 Spent grains 6.11 Theory of wort separation 6.12 References 7 Hops 7.1 Introduction 7.2 Botany 7.3 Cultivation 7.4 Drying 7.5 Hop products 7.5.1 Hop pellets 7.5.2 Hop extracts 7.5.3 Hop oils 7.6 Pests and diseases Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC 7.6.1 Damson-hop aphid 7.6.2 (Red) Spider Mite 7.6.3 Other pests 7.6.4 Downy mildew 7.6.5 Powdery mildew 7.6.6 Verticillium wilt 7.6.7 Virus diseases 7.7 Hop varieties 7.8 References 8 The chemistry of hop constituents 8.1 Introduction 8.2 Hop resins 8.2.1 Introduction 8.2.2 Biosynthesis of the hop resins 8.2.3 Analysis of the hop resins 8.2.4 Isomerization of the �-acids 8.2.5 Hard resins and prenylflavonoids 8.2.6 Oxidation of the hop resins 8.3 Hop oil 8.3.1 Introduction 8.3.2 Hydrocarbons 8.3.3 Oxygen-containing components 8.3.4 Sulphur-containing compounds 8.3.5 Most potent odorants in hop oil 8.3.6 Hop oil constituents in beer 8.3.7 Post fermentation aroma products 8.4 Hop polyphenols (tannins) 8.5 Chemical identification of hop cultivars 8.6 References 9 Chemistry of wort boiling 9.1 Introduction 9.2 Carbohydrates 9.3 Nitrogenous constituents 9.3.1 Introduction 9.3.2 Proteins 9.4 Carbohydrate-nitrogenous constituent interactions 9.4.1 Melanoidins 9.4.2 Caramel 9.5 Protein-polyphenol (tannin) interactions 9.6 Copper finings and trub formation 9.7 References 10 Wort boiling, clarification, cooling and aeration 10.1 Introduction 10.2 The principles of heating wort 10.3 Types of coppers 10.4 The addition of hops Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC 10.5 Pressurized hop-boiling systems 10.5.1 Low-pressure boiling 10.5.2 Dynamic low-pressure boiling 10.5.3 Continuous high-pressure boiling 10.6 The control of volatile substances in wort 10.7 Energy conservation and the hop-boil 10.8 Hot wort clarification 10.9 Wort cooling 10.10 The cold break 10.11 Wort aeration/oxygenation 10.12 References 11 Yeast biology 11.1 Historical note 11.2 Taxonomy 11.3 Yeast ecology 11.4 Cellular composition 11.5 Yeast morphology 11.6 Yeast cytology 11.6.1 Cell wall 11.6.2 The periplasm 11.6.3 The plasma membrane 11.6.4 The cytoplasm 11.6.5 Vacuoles and intracellular membrane systems 11.6.6 Mitochondria 11.6.7 The nucleus 11.7 Yeast cell cycle 11.7.1 Yeast sexual cycle 11.8 Yeast genetics 11.8.1 Methods of genetic analysis 11.8.2 The yeast genome 11.9 Strain improvement 11.10 References 12 Metabolism of wort by yeast 12.1 Introduction 12.2 Yeast metabolism – an overview 12.3 Yeast nutrition 12.3.1 Water relations 12.3.2 Sources of carbon 12.3.3 Sources of nitrogen 12.3.4 Sources of minerals 12.3.5 Growth factors 12.4 Nutrient uptake 12.4.1 Sugar uptake 12.4.2 Uptake of nitrogenous nutrients 12.4.3 Lipid uptake 12.4.4 Ion uptake 12.4.5 Transport of the products of fermentation Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC 12.5 Sugar metabolism 12.5.1 Glycolysis 12.5.2 Hexose monophosphate (pentose phosphate) pathway 12.5.3 Tricarboxylic acid cycle 12.5.4 Electron transport and oxidative phosphorylation 12.5.5 Fermentative sugar catabolism 12.5.6 Gluconeogenesis and the glyoxylate cycle 12.5.7 Storage carbohydrates 12.5.8 Regulation of sugar metabolism 12.5.9 Ethanol toxicity and tolerance 12.6 The role of oxygen 12.7 Lipid metabolism 12.7.1 Fatty acid metabolism 12.7.2 Phospholipids 12.7.3 Sterols 12.8 Nitrogen metabolism 12.9 Yeast stress responses 12.10 Minor products of metabolism contributing to beer flavour 12.10.1 Organic and fatty acids 12.10.2 Carbonyl compounds 12.10.3 Higher alcohols 12.10.4 Esters 12.10.5 Sulphur-containing compounds 12.11 References 13 Yeast growth 13.1 Introduction 13.2 Measurement of yeast biomass 13.3 Batch culture 13.3.1 Brewery batch fermentations 13.3.2 Effects of process variables on fermentation performance 13.4 Yeast ageing 13.5 Yeast propagation 13.5.1 Maintenance and supply of yeast cultures 13.5.2 Laboratory yeast propagation 13.5.3 Brewery propagation 13.6 Fed-batch cultures 13.7 Continuous culture 13.8 Immobilized yeast reactors 13.9 Growth on solid media 13.10 Yeast identification 13.10.1 Microbiological tests 13.10.2 Biochemical tests 13.10.3 Tests based on cell surface properties 13.10.4 Non-traditional methods 13.11 Measurement of viability 13.12 Assessment of yeast physiological state 13.13 References Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC 14 Fermentation technologies 14.1 Introduction 14.2 Basic principles of fermentation technology 14.2.1 Fermentability of wort 14.2.2 Time course of fermentation 14.2.3 Heat output in fermentation 14.3 Bottom fermentation systems 14.3.1 Choice, size and shape of vessels 14.3.2 Construction of cylindroconical vessels 14.3.3 Operation of cylindroconical vessels 14.4 Top fermentation systems 14.4.1 Traditional top fermentation 14.4.2 Yorkshire square fermentation 14.4.3 Burton Union fermentation 14.5 Continuous fermentation 14.5.1 Early systems of continuous fermentation 14.5.2 The New Zealand system 14.5.3 Continuous primary fermentation with immobilized yeast 14.6 Fermentation control systems 14.6.1 Specific gravity changes 14.6.2 Other methods 14.7 Summary 14.8 References 15 Beer maturation and treatments 15.1 Introduction 15.2 Maturation: flavour and aroma changes 15.2.1 Principles of secondary fermentation 15.2.2 Important flavour changes 5 15.2.3 Techniques of maturation 15.2.4 Flavour, aroma and colour adjustments by addition 15.2.5 Maturation vessels 15.3 Stabilization against non-biological haze 15.3.1 Mechanisms for haze formation 15.3.2 Removal of protein 15.3.3 Removal of polyphenols 15.3.4 Combined treatments to remove protein and polyphenols 15.3.5 Hazes from other than protein or polyphenols 15.4 Carbonation 15.4.1 Carbon dioxide saturation 15.4.2 Carbon dioxide addition 15.4.3 Carbon dioxide recovery 15.5 Clarification and filtration 15.5.1 Removal of yeast and beer recovery 15.5.2 Beer filtration 15.6 Special beer treatments 15.6.1 Low-alcohol and alcohol-free beers 15.6.2 Ice beers 15.6.3 Diet beers Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC 15.7 Summary 15.8 References 16 Native African beers 16.1 Introduction 16.1.1 An outline of the stages of production 16.1.2 Bouza 16.1.3 Merissa 16.1.4 Busaa and some other beers 16.1.5 Southern African beers 16.2 Malting sorghum and millets 16.3 Brewing African beers on an industrial scale 16.4 Attempts to obtain stable African beers 16.5 Beer composition and its nutritional value 16.6 References 17 Microbiology 17.1 Introduction 17.2 The microbiological threat to the brewing process 17.3 Beer spoilage micro-organisms 17.3.1 Detection of brewery microbial contaminants 17.3.2 Identification of brewery bacteria 17.3.3 Gram negative beer spoiling bacteria 17.3.4 Gram positive beer spoiling bacteria 17.3.5 Beer spoilage yeasts 17.3.6 Microbiological media and the cultivation of micro-organisms 17.4 Microbiological quality assurance 17.5 Sampling 17.5.1 Sampling devices 17.6 Disinfection of pitching yeast 17.7 Cleaning in the brewery 17.7.1 Range of cleaning operations 17.7.2 CIP systems 17.7.3 Cleaning agents 17.7.4 Cleaning beer dispense lines 17.7.5 Validation of CIP 17.8 References 18 Brewhouses: types, control and economy 18.1 Introduction 18.2 History of brewhouse development 18.2.1 The tower brewery lay-out 18.2.2 The horizontal brewery lay-out 18.3 Types of modern brewhouses 18.3.1 Experimental brewhouses 18.3.2 Micro- and pub breweries 18.4 Control of brewhouse operations 18.4.1 Automation in the brewhouse Copyright © 2004 Woodhead Publishing Limited and CRC Press, LLC