Food Taints and OtT-Flavours Food Taints and Off-Flavours Second edition Edited by M J SAXBY A fonner Manager Analytical Chemistry Section Leatherhead Food Research Association Surrey SPRINGER-SCIENCE+BUSINESS MEDIA, B.V First edition 1993 Second edition 1996 © 1996 Springer Science+Business Media Dordrecht Originally pubIished by Chapman & Hali in 1996 Softcover reprint of the hardcover 2nd edition 1996 Typeset in 1O/12pt Times by AFS lmage Setters Ltd, Glasgow ISBN 978-1-4613-5899-2 ISBN 978-1-4615-2151-8 (eBook) DOI 10.1007/978-1-4615-2151-8 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior pennission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the tenns of licences issued by the appropriate Reproduction Rights Organization outside the UK Enquiries concerning reproduction outside the tenns stated here should be sent to the publishers at the Glasgow address printed on this page The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made A catalogue record for this book is available from the British Library Library of Congress Catalog Card Number: 95-79979 ~ted on acid-free paper, manufactured in accordance with ANSI/NISO Z39.48-1992 (Permanence ofPaper) Contributors Mrs S J E Bennett BRF International, Lytlel Hall, Coopers Hill Road, Nutfield, Redhill, Surrey RHl4HY, UK Mr D A Cumming Fonnerly with Safeway Stores pic, Beddow Way, Aylesford, Maidstone, Kent ME20 7AT, UK Prof Dr H W Grosch Deutsche Forschungsanstalt ftir Lebensmittelchemie, Lichtenbergstra8e 4, D-85748 Garching, Gennany ProfessorI.J.Jeon Department of Animal Sciences and Industry, 139 Call Hall, Kansas State University, Manhattan, Kansas 66506-1600, USA D.Khiari UCLA School of Public Health, Los Angeles, CA 90024-1772, USA Dr D Kilcast Sensory Analysis and Food Texture Section, Leatherhead Food Research Association, Randalls Road, Leatherhead, Surrey KT22 7RY, UK Dr S P Kochhar SPK Consultancy Services, 48 Chiltern Crescent, Earley, Reading RG6 IAN, UK DrH.Maarse TNO Division of Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Dr J Mallevialle Central Laboratory-CIRSEE, Lyonnaise des Eaux et Dumez, 38 Rue du President Wilson, 78230 Le Pecq, France Mr R M Pascal Fonnerly with Safeway Stores pic, Beddow Way, Aylesford, Maidstone, Kent ME20 7AT, UK Dr M J Saxby 84 Pixham Lane, Dorking, Surrey, RH4 IPH, UK Dr M B Springett Neotronics Scientific Ltd, Western House, Cambridge Road, Stansted Mountfitchet, Essex CM24 8BZ, UK Dr I H (Mel) Suff'et UCLA School of Public Health, Los Angeles, CA 90024-1772, USA Mr K Swoff'er Safeway Stores pic, Beddow Way, Aylesford, Maidstone, Kent ME20 7AT, UK DrP Tice PIRA International, Randalls Road, Leatherhead, Surrey KT22 7RU, UK Preface Contamination of food with extremely low levels of certain organic compounds can lead to a very unpleasant taste This can result in the destruction of vast stocks of product and very substantial financial losses to food companies The concentration of the alien compound in the food can be so low that very sophisticated equipment, operated by experienced staff, is needed to identify the compound and to determine its source It is therefore vital that every company involved in the production, distribution and sale of foodstuffs is fully aware of the ways in which this contamination can occur, how it can be avoided and what steps need to be taken in the event that the problem does arise In the past it is regrettable that many instances of serious taints in a food have not been investigated, so that their cause, source and removal have remained unresolved Sometimes this may have been caused by the lack of sufficiently sensitive analytical equipment required for the identification of the compound, but it is more often because the expertise needed to interpret all the clues has not been available This book provides the background information needed for personnel to recognise how food can become tainted, how to draw up guidelines to prevent this contamination, and how to plan the steps that should be taken in the event of an outbreak For the reader in academic and research institutions, the book provides a very extensive literature survey as a basis for future research The totally revised second edition of the book consists of ten chapters, each written by specialist authors, known for expertise in their own subject It sets out to present this unique subject in a way which will be understandable to academic, technical and commercial staff The importance of detecting the presence of a taint in a foodstuff by organoleptic methods, both as a preventive measure and in the early stages of an investigation, is dealt with in the first chapter The second chapter is an extensive survey of chemical compounds that can cause taints and looks at their origin, while the following chapter deals with the critical subject of their analysis The opportunity has been taken for total revision of this chapter by a new author The next three chapters deai with taints in water, dairy products and fats Two further chapters are written by experts in the packaging indsutry and in the retailing sector The penultimate chapter deals with the incidence of microbiologically formed off-flavours The final chapter is totally new and is a survey of off-flavours in alcoholic beverages, with particular reference to beer M.l.S Contents Sensory evaluation of taints and off-flavours D.KILCAST 1.1 Introduction Thresholds and their measurement Sensory descriptions of taints and off-flavours Principles of sensory evaluation of food 1.4.1 Analytical tests 1.4.2 Hedonic tests 1.4.3 Requirements for a sensory evaluation operation 1.5 Sensory testing for taint 1.5.1 Test selection and modification 1.5.2 Diagnostic taint testing 1.5.3 Preventive (taint-transfer) testing 1.5.4 Sensory quality control taint testing 1.5.5 Storage and shelf-life testing 1.6 Ethical considerations I Future developments References 1.2 1.3 1.4 A survey of chemicals causing taints and off-flavours in foods M.l.SAXBY 2.1 2.2 Introduction Taints derived from known chemicals 2.2.1 Phenols 2.2.2 Chlorophenols 2.2.3 Bromophenols 2.2.4 Haloanisoles 2.2.5 Compounds containing sulphur 2.2.6 Alcohols 2.2.7 Hydrocarbons 2.2.8 Esters and ethers 2.2.9 Amines 2.2.10 Chlorinated hydrocarbons 2.2.11 Carbonyl compounds 2.2.12 Furans and oxygen-ring compounds 2.2.13 Fatty acids References Analysis of taints and off-flavours I II 15 15 19 20 21 21 25 26 30 31 34 37 38 41 41 44 44 46 48 49 53 55 56 60 61 62 63 65 66 66 72 H MAARSE and H W GROSCH 3.1 3.2 3.3 Introduction Instrument analysis 3.2.1 Preparation of the concentrates 3.2.2 Separation 3.2.3 Identification Sensory methods 3.3.1 Introduction 3.3.2 Control of concentration procedures 72 73 73 79 82 83 83 83 x CONTENTS 3.3.3 Selection of off-flavour compounds 3.3.4 Confinnation of the contribution of identified compounds to the off-flavour 3.4 Examples of off-flavour studies 3.4.1 Introduction 3.4.2 Application of dilution techniques 3.4.3 Odorous contaminants 3.5 Conclusions References Taste and odor problems in drinking water I H (MEL) SUFFET, D KHIARI and J MALLEVIALLE 4.1 4.2 4.3 4.4 4.5 4.6 Introduction Off-flavors in drinking water and their relation to drinking water standards Classifying tastes and odors The causes of tastes and odors in water supplies Cause-and-effect relationships in drinking water taste and odor problems Specific taste and odoHausing compounds 4.6.1 Geosmin 4.6.2 Methyl isobomeol (MIB) 4.6.3 Chlorine 4.6.4 Chloramine 4.6.5 Chlorination by-products 4.7 Treatment of specific odorous chemicals 4.8 Taste and odor treatment of off-odors by chlorination and chloramination 4.9 Taste and odor treatment of off-odor by ozonation 4.10 Taste and odor treatment by carbon adsorption 4.11 Summary References Undesirable flavors in dairy products I J JEON 5.1 5.2 5.3 Introduction Sensory characteristics of off-flavors Transmitted off-flavors 5.3.1 Barny flavor 5.3.2 Cowy flavor 5.3.3 Feed flavor 5.3.4 Weed flavor 5.4 Lipolyzed flavor 5.4.1 Lipoprotein lipase 5.4.2 Microbiallipases 5.4.3 Flavor characteristics of lipolytic products 5.5 Microbial flavors 5.5.1 Acid flavor 5.5.2 Bitter flavor 5.5.3 Fruity flavor 5.5.4 Green flavor 5.5.5 Malty flavor 5.5.6 Moldy or musty flavor 5.5.7 Miscellaneous microbial flavors 5.6 Heat-induced flavors 5.7 Oxidized flavor 5.7.1 Mechanisms and conditions 5.7.2 Reaction products 5.8 Miscellaneous off-flavors Acknowledgement References 84 87 87 87 88 95 103 103 107 107 107 108 110 114 115 115 115 115 116 117 123 124 128 132 133 133 139 139 139 141 141 142 142 143 144 144 145 146 148 148 148 149 150 151 151 151 152 155 155 158 160 162 163 CONTENTS Oxidative pathways to the formation of orr-flavours xi 168 S P KOCHHAR 6.1 6.2 Introduction Unsaturated lipids as off-flavour precursors 6.2.1 Free-radical autoxidation 6.2.2 Photo-sensitised oxidation 6.2.3 Factors affecting the rate of lipid oxidation 6.2.4 Fonnation of hydroperoxides (off-flavour precursors) 6.3 Decomposition of hydroperoxides and types of off-flavour compounds 6.3.1 Aldehydes 6.3.2 Ketones 6.3.3 Furans 6.3.4 Furanoid fatty acids and dicarbonyl compounds 6.3.5 Alcohols 6.3.6 Acids 6.3.7 Hydrocarbons 6.4 Miscellaneous off-flavours and precursors 6.5 Conclusions Acknowledgement References Packaging material as a source of taints 168 170 170 172 173 181 186 188 202 206 208 210 212 214 215 217 218 218 226 P nCE 7.1 7.2 Introduction Standard odour and taint assessment methods 7.2.1 Legislation 7.2.2 Test methods 7.2.3 Precautions in selecting transponing and handling samples for sensory testing 7.3 Printing inks and adhesives 7.3.1 Printing ink and varnish types 7.3.2 Precautions to prevent odour and tainting from printed packaging 7.3.3 Methods for detennining levels of residual solvents 7.3.4 Some reponed odour and taint investigations 7.4 Paper and board packaging 7.5 Plastics packaging 7.6 Chlorophenols and chloroanisoles 7.7 •Scalping' of food aromas and flavours by packaging 7.8 Analytical methods for isolating and identifying odorous and tainting substances References A retailer's perspective 226 229 229 230 235 235 236 237 239 241 242 246 252 254 256 260 264 D A CUMMING, K SWOFFER and R M PASCAL 8.1 8.2 Introduction Product recall 8.2.1 Does a problem exist? 8.2.2 What is the problem? 8.2.3 How widespread? 8.2.4 Stockholding 8.2.5 Store!branch product removal 8.2.6 Major incidents 8.3 Case histories 8.4 Avoidance of taint Acknowledgement 264 265 265 266 267 267 267 267 268 271 273 xii CONTENTS Formation of off-flavours due to microbiological and enzymic action M B SPRINGETT 9.1 9.2 9.3 9.4 Introduction 9.1.1 Off-flavours prefonned in the food 9.1.2 Off-flavours fonned as a result of cellular disruption 9.1.3 Off-flavours arising as a consequence of microbial deterioration Milk and dairy products 9.2.1 Lipases 9.2.2 Proteinases 9.2.3 Other defects Fruit and vegetables 9.3.1 Citrus fruits 9.3.2 Legumes 9.3.3 Brassicas 9.3.4 Potato 9.3.5 Cucumber and lettuce Wine and beer 9.4.1 Wine 9.4.2 Beer Meat and fish Concluding remarks 9.5 9.6 Note References 10 Off·f1avours in alcoholic beverages S J E BENNETT 10.1 Introduction 10.2 Beer 10.2.1 Raw materials 10.2.2 Processing 10.2.3 Microbiological spoilage 10.2.4 Packaging 10.2.5 Storage 10.2.6 Accidental contamination 10.3 Cider 10.3.1 Raw materials 10.3.2 Processing 10.3.3 Microbial spoilage 10.3.4 Packaging 10.3.5 Storage 10.3.6 Accidental contamination 10.4 Sak~ 10.5 Wine and fortified wine 10.5.1 Raw materials 10.5.2 Process 10.5.3 Microbial spoilage 10.5.4 Packaging 10.5.5 Storage 10.6 Conclusions Acknowledgments References Index 274 274 274 274 274 275 275 275 276 276 276 277 279 280 280 281 281 283 284 286 286 286 290 290 292 294 297 300 303 305 308 309 309 310 310 311 311 311 311 312 312 314 315 315 316 316 317 317 321 312 FOOD TAINTS AND OFF-FLA YOURS (1976) as 3-hydroxy-4,5-dimethyl-2(5H)-furanone In addition, as sake ages, it is perceived as more bitter The deterioration in flavour is accelerated with temperature According to Takahashi and Akiyama (1993), this aged flavour is improved on return to the sake plant and treatment with activated carbon Furthermore, they suggest sake should be consumed within 3-4 months of bottling If sake is exposed to sunlight or fluorescent light (280-380 nm) the colour changes and an off-flavour termed 'nikko-shu' develops after a short time (Sato et al., 1968) Although not yet fully understood, methyl mercaptan is thought to be responsible for the off-flavour If bottled in emerald green or brown bottles the sake is apparently protected Hiochi-ka is the off-flavour that develops when sake becomes infected with Lactobacillus spp ('hiochi bacteria') Volatile acids and diacetyl (which has a flavour threshold in sake of 0.1 ppm) are the main causes of this off-flavour This problem can be controlled by rigorous attention to hygiene 10.5 Wine and fortified wine A huge diversity of flavours is found in both wine and fortified/liqueur wines The latter are wines to which a grape spirit such as brandy is added to increase the alcohol content This group of beverages includes sherry and port The grape variety, conditions under which it is grown and processed together with the actual vinification process all playa major role in the development of the final flavour In addition, the materials in which the wine is stored, the storage time and, in the case of fortified wines, the quality of the spirit added, can all influence the overall balance of flavour active compounds Whether the resultant flavour is deemed acceptable or unacceptable depends on the style of beverage and on the people who will finally consume it Amerine (1980) quotes the example of wines produced and appreciated along the Dalmatian coast, which are high in alcohol and tannin; in western Europe, such wines are generally considered too harsh Certain flavours, for example corked flavour (Anon., 1995) are always considered unpalatable Rapp et al (1992) reviewed the undesirable and foreign flavours which can be found in wine Table 10.3 lists the main off-flavours in wine and fortified wines and their possible causes 10.5.1 Raw materials Certain off-flavours arise in wine when specific grape varieties are used Both native American grapes Vitis labrusca and Vitis rotundifolia have a distinct flavour described as 'foxy' (Winckler, 1972; Bailey, 1988) This has also been found in wine made from cultivars derived from these species such as Concord (Sale and Wilson, 1926) The chemical compound(s) responsible for this flavour have not yet been identified OFF-FLA VOURS IN ALCOHOLIC BEVERAGES 313 Table 10.3 Off-flavours found in wine and fortified wines and their possible causes Off-flavour Descriptor Acetaldehyde Acetic acid Bitterness Blackcurrant Butyric acid Corked Emulsion paint Vinegar Eucalpytus Foxy Geranium Green Kerosene Lightstruck Medicinal Mousy Sauerkraut Sulphury Strawberry Volatile acidity Woody Possible cause Oxidation Microbial spoilage Bacterial spoilage Cultivar Bacterial spoilage Mouldy, musty Organo-chlorine compounds metabolised by moulds to chloroanisoles Maturation in new oak Camphor Carotene breakdown Cultivar Bacterial degradation of sorbic acid Grassy Unripe grapes Petrol Carotene breakdown Leek-like Light Cause unknown Acetamide Microbial spoilage (e.g from Brettanomyces and Lactobacillus spp.) Lactic acid, diacetyl Bacterial spoilage Hydrogen sulphide, cheese-like Yeast strain garlic, cabbage Lacquer breakdown on cans High levels of elemental sulphur Cuhivar Acetic acid and ethyl acetate Bacterial spoilage Malo-lactic fermentation Over extraction of lactones and phenols from wooden barrels A strawberry-like flavour has arisen in some vintages of wine made from the cultivar Pollux grown for its fungal-resistant properties Such cultivars have been obtained by cross-breeding wild American vines with European cultivars (Vitis vinifera) Rapp et al (1980) demonstrated, using gas chromatography-mass spectrometry (GC-MS), together with eluent sniffing, that the chemical responsible for the strawberry flavour was 2,5-dimethyl-4-hydroxy-2,3-dihydro3-furanone ('furaneol') This compound, which can be tasted at levels of 50-100 ppb (Rapp et al., 1992), has been associated specifically with wines made from interspecific varieties Consequently, the use of the gas chromatographic method for the detection of furaneol (detection limit ppb (Rapp et al., 1992)) has been incorporated in the screening of new grape varieties If grapes are grown in very cool climates they may not ripen sufficiently Such grapes may be low in sugar and of low pH (3 or below); the resultant wine can be 'thin' and 'green' (Drawert, 1974) Conversely grapes that become overripe in warmer climates have been associated with 'overripe', 'sunburned' and 'raisinlike' odours in wine (Amerine, 1980) The weather conditions to which the vine are subjected can also have an indirect effect on the final flavour of the wine Hail and frost can damage the fruit, which can then be subject to microbial spoilage and its concomitant flavour effects Organic insecticides and fungicides used in the vineyard to control infestations and infection may also indirectly affect the 314 FOOD TAINTS AND OFF-FLAVOURS flavour; the growth of the wine yeast may subsequently be inhibited, thereby altering the balance of flavours produced in fermentation and allowing opportunist infection to occur (Amerine, 1980) A rotten egg/cabbage/faecal smell, which developed slowly in bottled wine over a period of years, has been attributed to the use of an applied systemic insecticide (trade name, Orthene) with acephate as its active ingredient (Rapp et 01., 1992) With time, the acephate hydrolyses to methyl mercaptan, which subsequently oxidises to dimethyl disulphide; both compounds have very low flavour thresholds and were found by Rauhut (1988) and Rauhut et 01 (1989) to be responsible for this off-flavour 10.5.2 Process Organic sulphur compounds are also formed during fermentation and can give wine an unpleasant odour described as 'rotten eggs/garlic/onion' and 'burnt rubber'; collectively it is called 'bOckser aroma' (Rapp et 01., 1992) Of the sulphur-containing chemicals responsible, hydrogen sulphide is the most important Hydrogen sulphide, which has a recognition threshold of Ilg/l (Rapp et 01., 1992), is produced to a greater or lesser extent in every fermentation The amount generated depends mainly upon the yeast strain and the level of elemental sulphur available to the yeast Hydrogen sulphide can also be formed when yeast metabolises amino acids in the absence of elemental sulphur The main source of elemental sulphur is the Bordeaux mixture (copper sulphate) used to control powdery mildew, although the copper present in the fungicide acts as a sulphur scavenger Sulphur matches, wicks or discs ignited and suspended in casks to disinfect them are an additional source of sulphur (Halliday and Johnson, 1992) Hydrogen sulphide can also be formed during storage of wine on the lees, as the yeast begins to autolyse (Amerine, 1980) Nevertheless, while hydrogen sulphide is not normally produced in excess, it can react with other components within the wine to give more complex sulphur compounds For example, the reaction of hydrogen sulphide with ethanol or acetaldehyde can result in the formation of ethyl-mercaptan, which has a garlic odour This, in tum, can be oxidised to diethyl sulphide (Rapp et 01., 1992) The mercaptan compounds that contribute to the bOckser aroma and the mechanisms by which they are formed are not completely understood They can be removed by early racking (removal from the lees) and aerating (Amerine, 1980) or by adding a carefully controlled quantity of copper sulphate, with the hydrogen sulphide being precipitated as copper sulphide (Halliday and Johnson, 1992) Removal of the mercaptans is far more difficult The quality of the spirit added in the production of fortified wines will influence the final quality Amerine (1980) advises that high aldehyde- and high fuselspirits should be avoided The compressed air used in mixing the spirits can also be a source of undesirable flavours as it may contain traces of petroleum OFF-FLAVOURS IN ALCOHOLIC BEVERAGES 10.5.3 315 Microbial spoilage Certain Brettanomyces spp and Lactobacillus spp are responsible for 'mousiness' in wine (Peynaud and Domerq, 1959) This flavour, as in cider, is only volatile at neutral or high pH and is generally perceived some seconds after it has been tasted (Robinson, 1994) It is not easily removed from wine but can be prevented by the appropriate use of sulphur dioxide A flavour described as 'sauerkraut' may develop if wine is infected with lactic acid bacteria or during malo-lactic fermentations The main compounds responsible for this flavour are lactic acid and diacetyl The latter is probably the most important (Dittrich and Kerner, 1964) since wines lacking the off-flavour have an average diacetyl content of 0.2 {).4 mg/l compared with concentrations of 0.9-4.3 mg/l in wines with a sauerkraut off-flavour An increased level of volatile acidity (acetic acid and ethyl acetate) manifests itself as a vinegary, solvent aroma and taste, which masks other flavours Inherent in all wines is some volatility produced during primary fermentation This 'natural' level can be increased if malo-lactic fermentation occurs or the wine becomes infected with lactic or acetic acid bacteria Infection can lead to an increase in the level of acetic acid to its legal limit (Halliday and Johnson, 1992) To prevent infection oxygen should be excluded, casks stored at a relatively cool temperature and appropriate levels of sulphur dioxide employed A butyric off-flavour and increased bitterness have also been attributed to bacterial spoilage (Rapp et aI., 1992) Sulphur dioxide and sorbic acid (2,4-hexadienoic acid) are used by winemakers to prevent microbial spoilage However, a geranium leaf off-flavour develops when sorbate treated wine becomes infected with lactic acid bacteria (Burkhardt, 1973) Consequently sorbic acid, which effectively inhibits yeast growth, must be used in conjunction with sulphur dioxide, which itself prevents the growth of lactics Sorbic acid has also been implicated in the development of another off-flavour De Rosa et al (1983) found that the use of 200 mg/l in sparkling wine (Charmat method) resulted in levels of ethyl sorbate, which gave the product an unpleasant aroma of pineapple/celery 10.5.4 Packaging The 'corked' off-flavour in wine is described as 'mouldy and musty' and is responsible for considerable economic loss Many different compounds have been identified that could be responsible for this flavour In their review Rapp et al (1992) consider the two main theories as to how this flavour arises In the first, compounds generated in the manufacture of the cork (e.g lignin sulphonic acids, which are formed post-S02 treatment) dissolve into the wine and react with its ingredients The alternative theory involves the growth of microorganisms on the cork, which convert phenolic compounds to chloroanisoles These compounds together with 2methylisoborneol and geosmin have also been implicated in the mouldy musty taints found in some wine while in the cask (Amon et aI., 1987) This problem is 316 FOOD TAINTS AND OFF-FLA YOURS thought to have arisen when new oak barrels treated with chlorine-containing wood preservatives become infected The contamination of casks, barrels and dried additives by chlorophenolic compounds from insecticide-treated timber has also given rise to this problem Development of this off-flavour can be limited by preventing mould growth and by avoiding the use of chlorophenols or cleaning, sterilising formulations containing chlorine (Anon., 1995) The flavours of some wines benefit from storage in wooden casks; however, in excess, the compounds extracted from the wood can dominate and become unpleasant The flavour of wine can deteriorate on exposure to artificial or natural light This 'sunlight' flavour has been attributed to volatile sulphur compounds From experiments with champagne wine, Charpentier and Maujean (1981) found the damaging wavelength to be 340-441 nm 10.5.5 Storage The flavour of wine is affected by the time and temperature of storage Unlike the flavour of beer, however, which is generally at its best on leaving the brewery, the flavour of wine may be considerably improved with storage The situation is further complicated by the fact that, on further storage, the acceptable flavour that has developed may deteriorate Whether storage has a beneficial or deleterious effect will depend upon the style of wine and the conditions to which it has been subjected, particularly the amount of oxygen to which it has been exposed With the exception of fortified wines, such as sherry and madeira, aeration is avoided throughout production (Laws and Peppard, 1982) As wine oxidises it generally becomes darker in colour and cooked/rancid notes increase (Thoukis, 1974) Red wines are much more resistant to oxidation than white wines owing to their higher phenol content Nevertheless, red wines can oxidise; the fruity character becoming dull and an aldehyde note developing (Halliday and Johnson, 1992) 10.6 Conclusions Off-flavours in alcoholic beverages have a variety of origins Once detected in the marketplace, however, they can result in substantial losses; in the short term, costs are incurred salvaging the situation (although taints can rarely be satisfactorily removed) and, in the long term, consumer confidence in the product can be destroyed While the outcome of some investigations into flavour problems are not published, remaining confidential to individual companies, much has now been documented As a consequence, producers can implement prevention strategies - minimising the chance of a flavour problem by monitoring the raw materials, the in-process samples and the final product By rigidly enforcing process and product specification, the potential for off-flavours to arise and the concomitant costs involved can be reduced considerably OFF-FLAVOURS IN ALCOHOLIC BEVERAGES 317 Acknowledgements The author wishes to acknowledge Dr J P Murray, Dr C W Bamforth, Dr J R M Hammond and Mrs P A Sanders for their help during the preparation of this chapter; the forbearance of my husband; and the Director General of BRF International for permission to publish References Amerine, M A (1980) The words used to describe abnormal appearance, odor, taste, and tactile sensations of wines In The Analysis and Control of Less Desirable Flavors in Foods and Beverages Academic Press, London pp 319-351 Amon, J M., Simpson, R F and Vandepeer, J M (1987) A taint in wood-matured wine attributable to microbiological contamination of the oak barrel Wine Industr JI (2), 35 Andrews, D A (1979) Taints: flavour, descriptions and origins Brewer 6S (777), 236 239 Andrews, D A (1984) Processing in relation to flavour (Cass College Lecture) Brew Guardian 113 (2),28-33 Andrews, D A (1987) Beer off-flavours - their cause, effect and prevention Brew Guardian 116 (I), 14-15, 18-21 Anness, B and Bamforth, C W (1982) Dimethyl sulphide - a review J Inst Brew 88 (4), 244-252 Anon (1995) Mould-busting Wine Spirit Internat 63 Bailey, L H (1988) The Evolution ofour Native Fruits Macmillan, New York Bamforth, c W 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Beverage Production (Eds A G H Lea and J R Piggott), Blackie A & P, Glasgow, pp 66-69 Lee, S Y., Mabee, M S., Jangaard, N O and Horuichi, E K (1980) Pectinatus a new genus of bacteria capable of growth in hopped beer J.1nst Brew 86 (1),28-30 Maarse, H., Nijssen, L M and Angelino, S A G F (1987) Halogenated phenols and chloroanisoles; OFF-FLA VOURS IN ALCOHOLIC BEVERAGES 319 occurrence, fonnation and prevention Proc 2nd Wartburg Aroma Symposium, (Ed Rothe, M.), Akademie Verlag Madigan, D., McMurrough, I and Smyth, M R (1994) Rapid detennination of 4-vinyl guaiacol and ferulic acid in beers and worts by high-perfonnance liquid chromatography l Am Soc Brew Chem S2 (4), 152-155 McGarrity, M J (1990) Processes for the reduction of organic contarninantlevels in water Louvain Brew Lett (3/4),3-11 Meaden, P (1994) Padding out the POF gene Ferment (4), 229-230 Meilgaard, M C (1972) Stale flavour carbonyls in brewing Brew Dig 47 (4), 48-52, 54, 56 57, 62 Meilgaard, M C (1975) Aavor chemistry of 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Somerset West, 28 Feb-4 Mar, lOB (Cent & South African Sect.)Johannesburg, pp 195-212 Nykanen, L and Suomalainen, H (1983) Aroma of Beer Wine and Distilled Alcoholic Beverages, Riedel, Holland Oag, I D M and Webb, T J B (1984) Practical experiences of packaging beer in 'PET' bonles Tech Q Master Brew Assoc Am 21(3),131-139 O'Connor-Cox, E S c., Yui, P M and Ingledew, W M (1991) Pasteurization: thennal death of microbes in brewing Tech Q Master Brew Assoc Am 28 (2), 67-77 Peppard, T L and Laws, D R J (1979) Hop-derived sulphur compounds and their effect on beer flavour Proc Eur Brew Conv.17th Congress Berlin, EBC, Ronerdam, pp 91-104 Penipher, G (1993) HACCP audits -a route to safety and quality Brewer 79 (942),156 158 Peynaud, E and Domerq, S (1959) A review of microbiological problems in wine-making in France, Am l Enol Viticol 10(2),69-77 Phipps, M E (1990) Brewing mold control Brew Dig 6S (7), 28-29 Rapp, A., Krupser, W., Engel, L., Ullemeyer, H and Heimann, W (1980) Vitis 19,13-23 Rapp, A., Pretorus, P and Kugler, D (1992) Foreign and undesirable flavours in wine In OffFlavours in Foods and Beverages (Ed G Charalambous), Elsevier Science Amsterdam, pp 485-522 Rauhut, D (1988) Proceedings ofthe International Symposium on Chromatography Wien Volume 2, 1988 Rauhut, D., Sponholz, W and Dittrich, H H (1989) Deutsche Weinbau Technik 16, 873-874 Reinke, H G., Hoag, L E and Kincaid, C M (1963) Effect ofantioxidants and oxygen scavengers on the shelf-life ofcanned beer Proc Am Soc Brew Chem 21,175-180 Richards, M (1976) Quality hazards to brewery water supplies Brew Dig SI (8), 34-36, 38, 40, 42 Robinson, (1994) The Oxford Companion to Wine Oxford University Press, p 382 Ryder, D S., Power, J and Siebel, R E (1989) A question of flavour stability or instability Proc Conv.lnst Brew (Cent and South African Sect.), 12th-16th Feb, lOB (Cent & South Africa Sect.), Johannesburg, pp 366 391 Sakuma, S., Rikimaru, Y., Kobayashi, K and Kowaka, M (1991) Sunstruck flavour fonnation in beer l Am Soc Brew Chem 49 (4), 162-165 Sale, T W and Wilson, T B (1926) Distribution of volatile flavour in grapes and grape juice l Agr Res 33(4), 301-310 Sato, S., Nakamura, K., Yao, T and Tadenuma, M (1968) Srudies on colorants in sake (Xill) Color development of sake by various treatments l Brew Soc lpn 63(4), 457-460 Sato, S., Tadenuma, M., Takahashi, K and Koike, K (1975) l Brew Soc lpn 70(8), 588-591 Schmidt, H (1988) Beer defects caused by microorganisms Brauwelt Int 1,72-74 Seaton, I C and Moir, M (1987) Sulphur Compounds and their Impact on Beer Aavour Eur Brew Cony Monogr III Symposium on Hops Weihenstephan, 18th Sept, Verlag, Nurnburg, pp 13(}"'145 Simpson, W J and Hammond, R M (1988) Cold ATP Extraclants compatible with conslantlight signal firefly luciferase reagents Soc Appl Bacteriol Proc Technical Series 26, ATP 320 FOOD TAINTS AND OFF-FLAVOURS Luminescence (&Is P E Stanley, B J McCarthy and R Smither), Blackwell Scientific Publications, Oxford, 45-52 Simpson, W J and Hammond, J R M (1990) A practical guide to the acid washing of brewers' yeast Ferment (6), 363-365 Statutory Instrument (SI) (1989) No 533 Food Composition and Labelling the Preservatives in Food Regulations 1989 Stenius, V., Majamaa, E., Haikora, A., Henriksson, E and Virtanen, H (1991) Beer off-flavours originating from anaerobic spore-forming bacteria in brewery adjuncts Proc Eur Brew Conv., 23rd Congress, Lisbon, Oxford University Press, Oxford, pp 529-536 Suihko, M-L., Pentilla, M., Scrie, H., Home, S., Blomquist, K., Tanaka, 1., Inoue, T and Knowles, J (1989) Pilot brewing with a-acetolactate decarboxylase active yeasts Proc Eur Brew Conv., 22nd Congress, Zurich, Oxford University Press, Oxford, pp 483-490 Takahashi, K and Akiyama, H (1993) The shelf-life of sake In Shelf Life Studies of Foods and Beverages (Dev Food Sci., 33) (Ed G Charalambous), Elsevier Science London, pp 1003-1031 Takahashi, K., Tadenuma, M and Sato, S (1976) 3-Hydroxy-4,5-dimethyl-2(5H)-furanone, a burnt flavoring compound from sake Agr Bio[ Chem 40 (2), 325-330 Thoukis, G (1974) Chemistry of wine stabilisation In Chemistry of Winemaking (Ed A D Webb), Adv Chem 137, 116-133 Tressl, F., Friese, R L., Fedesack, F and Koppler, H (1978) Studies of the volatile composition of hops during storage.J Agr FoodChem 26 (6),1426-1430 Tressl, R., Barhi, D and Kossa, M (1980) Formation of off-flavour components in beer In The Ana[ysis and Control of Less Desirab[e F[avours in Food and Beverages (Ed G Charalambous), Academic Press, London, pp 293-318 Tucknott, O G (1977) The Origin of Mousiness in Fermented Beverages PhD Thesis, University of Bristol, UK Tucknott, O G (1978) flavour taints in fermented beverages In Long Ashton - First Cider Subject Day, University of Bristol, pp 3-9 Vilpola, A (1985) Preventing beer oxidation with antioxidant Mal/as O[ut 6, 178-184 Wass, R (1970) Coping with the problems of odors and taste caused by algae in water Tech Q Master Brew Am Assoc (I), 50-54 White, F H (1977) The origin and control of dimethyl sulfide in beer Brew Digest 52 (5), 38-44, 46-48,50 Whitear, A L., Carr, B L., Crabb, D and Jacques, D (1979) The Challenge of flavour Stability Proc Eur Brew Conv., Berlin pp 13-25 Williams, A A (1974) 11Je aroma components of cider apples and fermented ciders Geruch- und Geschmackstrofle Int Symp pp 141-151 Winckler, A T (1972) Genera[ Viticulture University of California Press, Berkeley Index aceUddehyde 250 acetylpyroline 61 acetyltetrahydropyridine 62, 283 acids aliphatic 212 acrylates 237 adhesives 235-242 alcohols 210 aldehydes 188-202,190,197,281 aminoacetophenone 61 anthranilate methyl 61 antioxidants 179 beer 307 appearance definition apple 309 aromagram see gas chromatography ASTM test method 233 autoxidation 170 mechanism 171 bacteria 300-303 beans 55,277 beer 47,54,61,66,283-284,292-309 benzophenone 237 bis-(methylio)methane 285 bread 54,65 bromoanisoles 53 bromophenols 48-49 Brussels sprouts 278 buns 57 butter 57,92-94, 140,203,204 butyrate ethyl 61,150 butyricacid 60,66,147,213,283 cabbage 279 cakes 57 cans 303 caproic acid see hexanoic acid carrot 64 carton board 242-246 catty taint see taint cheese 56, 95 chloramine 116 chlorine 115 6-chloro-o-cresol 46-47 chloroanisoles 49-53,97-99,112 analysis 53 chlorophenols 46-48,113,118,252,269 2-chlorophenol 119 chocolate 60 choloranisoles 252 cider 309-311 cinnamaldehyde degradation 58 citra! degradation 59 citrus fruits 278 clam 55 classification of taste and odours in water 108 cocoa 253 coconut 64 coffee 51 containerftoo~ 47,52 corks 51 corned beef 269 cotton seed oil 58 coumarin 65 cresols 45 cucumber 278,280 cucurbitaein E 278 customer complaints 265-266 dairy products 139,275-276 decadienal 113 decatrienal 63, 216 decyne 59,214,215 degradation cinnamaldehyde 58 citra! 59 sorbic acid 56-57,60 vanillin 45 descriptive test 18-19 diacetyl 155,283,299 dichlorobenzene 63 dichlorophenols 47,119,253 difference from control test 17 difference test 15-16 dihydroactinidiolide 64 dilution analysis 85-87 dimethyl disulphide 112 322 INDEX dimethyl sulphide 54 dimethyl trisulphide 54, 112 dimethyl-4-hydroxy-2,3-dehydrofuranone 313 2.6-dimethylrnethoxypyrazine 62 dimethylstyrene 59 dioxacyclodecane-7,12-dione 65 discriminative test see difference test 2,4-dithiapentane 54 drain cleaners 46, 63 duo-trio test 17 enzymes 177, 274 epoxy aldehydes 201 epoxy decenal 200 epoxy heptenal 200 epoxy nonenal 200 ethoxyhexadiene 60 ethyl-5,5-dimethyl-I.3-dioxane 65 extraction adsorption 77-79 combined steam distillation extraction 73-74 Likens-Nickerson 73-74 Soxhlet 74 stripping systems 77-79 vacuum distillation 75 fats 170 see also oil, edible fennentation 298 fish 46,48,55.59,61,88.99,268.284-285 flavour definition reversion 65, 200 flooring materials 44 fruit 276-281 furaneol 313 furans 206 gas chromatography capillary 79 sniffing 84-87.88,91.95.102 two-dimensional 79-80 geosmin 55-56,112,115,282.285,316 goitrin 278 grapes 312 guaiacol 45,282 headspace analysis 76, 95 hedonic tests 19-20 heptadienal 112, 159 heptanone 64 hepten-3-one 250 hexanoate ethyl 61,150 hexanoic acid 60,213 hexenal 92, 281 hexyne 214 high-perfonnance liquid chromatography 81 hops 296 hydrocanbons 214 hydroperoxides beer 306 decomposition 186-215 fonnation 181-186 ice cream 140 indole 61,113,143.310 infrared spectrophotometry 257 inks see printing inks iodomethanes 119 ionone 64.156 isopropyl-5,5-dimethyl-I.3-dioxane 65 lactucin 278 legumes 277 lettuce 278 280 light struck 162 Likens-Nickerson extraction 73 limonin 276, 278 lipase 275 Maillard reaction 297 malonaldehyde fonnation 199 malt 295-296 malting 295 mass spectrometry 82-83 89, 256 selected ion monitoring 82-83 maturation beer 299 meat 63,284-285 mercaptans 113 mercaptomethylpentanone 53.241.305 mesityloxide 53-54 242 metals 175-177 beer 308 methional 89 methoxy isopropylpyrazine 112 2-methoxy-3-isopropylpyrazine 62 2-methoxy phenol see guaiacol 2-methyl butanal 118 methyl benzyl sulphide 55 3-methyl butanal 118,151 methyl isobomeol 56,112,115,282,285 315 methyl phenols see cresols 2-methyl propanol 118 methylbut-2-en-l-thiol 304 methylpentenal 95 microbial spoilage 274-286 cider 310 wine 315 mi~ 47,55,60.64.140,268,276.278 dried 61.63,203 323 INDEX UHT 152 millet grits 61 moulds 302 composition 236 processing cider 310 wine 314 product recall 265-268 propylphenols see phenols, alkyl proteinase 275 naphthol 290 naringin 278 nonadienal 89,92,159 nonane-2,4-dione 209 nonanol 203 nonenal 14,63,89,94,194,306 nuts 54 quality control 30-31 octadien-2-one 204 octadien-3-one 64,89,204 octan-3-one 203 octen-3-one 64,89,159,202,204 odour see sensory description off-flavour see taint definition oil spillage 59 oil, edible 58,65, 186 off-flavour in 63 refining 173 orange juice 46 organochlorine pesticides 62 oxidation beer 306-308 ownisation 128 packaging 65,95,303 cider 311 legislation 229-230 prevention of taint 237-239 residual solvents 239-241 taint transfer 254 test methods 230-235 wine 315 paired comparison test 16 pallets 50-51 paraffins 59 pasteurisation 299 peas 279 1,3-pentadiene 56-57 2-pentylfuran 65, 206, 279 peroxidation beer 306-308 pesticides organochlorine 62 phenols 44-49,99-101,118 alkyl 44,46 phenylacetaldehyde 118 plastics packaging 246 polyethylene 251 polyethylene terephthalate (PET) potato 280 potato chips 58, 61 prawns 54,102 printing inks 235-242 250 R-index test 17 recycling 13 reference standards of odours rice 54 I 10 sake 311-312 sausage 65 sensory description 5,11-15,91,109-110, 140 see a/so gas chromatography, sniffing sensory profile tests 19 water 125 sensory taint tests 21-34 sensory test methods 15-34 procedures 20-21 shelf-life testing 31-34 shrimps 49 skatole 61,143 solvents 239 sorbic acid degradation 56-57, 60 soyabean oil 186 standards water quality 107-108 storage 305-308 cider 311 wine 316 styrene 57,247 sulphides 54,112,143,153,280,281,296, 298,311,314 taint acidic in beer 293 almond 95 incheese 95 in meat 63 astringent 160 in beer 290, 293 avoidance 271-273 barny in milk 141 beany 65,187 in oil 215,206 bitter 66,148-149, 187 in beer 293 in citrus 276 in cucumber 280 324 taint, bitter con!' d in wine 313 burnt in milk 55, 162 cabbage in hops 296 in milk 153 in wine 314 cardboard 187,268,306 in beer 293, 305 in butter 92 in dairy products 158 in milk 155 catty 53 in beer 305 in cider 309, 311 in print 241 in rice 54 chalky 160 cheesy 66,160-161 in beer 283, 293 in hops 296 chemical in water 114 cooked 152-155 cork in wine 282,313 cowy in cheese 147 in milk 142 definition 2,3,41-43 dirty dishcloth 62 disinfectant 268 in poultry 46 drains 45 in potato 280 earthy in water 55, 56 fatty 65, 187 in beer 298 in fish 88, 92 fishy 62,187,216 in beer 293 in butter 64 in dairy products 158 in oil 63 in water 124, 125 flat in cheese 161 floral 64 foxy in wine 61,312,313 fruity 187 in milk 149 garlic inhops 206 inmilk 143 in prawns 285 in seafood 102 genuriurn 200,237 in cider 309, 311 in wine 283,313, 315 gluey in cheese 161 goaty INDEX in beer 293, 298 in milk 144 grassy 65,187 in beer 293 in milk 142 in oils 206,215 green 160 in fish 88,92 in milk 142 in soya oil 200 in wine 281,313 in yoghurt 150 hay 64 in beer 294 in dairy products 156 in soya oil 200 heat-induced 152 kerosene 57 light struck in beer 304 in potato chips 58-59 in wine 313,316 malty in dairy products 151 medicinal in beer 294 in water 125 in wine 282 metallic 54,187,200,202,269 in beer 294,304 in butter 64, 204 in dairy products 158 in milk 155 in oils 206 mice in cider 309 in wine 283,313 microbiological in water 114 mousy in wine 62 mushroom 202 in milk 210 musty 14,64,210 in beer 294 in fish 285 in poultry 49-53 in water 56 in wine 313 naphthalene 61 nutty 187 oily in beer 294 in dairy products 158 onion 54 incheese 95 in milk 143 oxidised 155-158,187,210 in dairy products 158 painty 14,57, 187 in dairy products 158 325 INDEX phenolic 269 in beer 294 pigsty 45 in potato 280 plastic 14, 57 in beer 294 prevention 302 rancid 187,210 in milk 144, 147 in oils 203,215 removal by ozonisation 128 in water 123-133 with carbon 132 salty in milk 162 skunlcy in beer 304 smoky in ice cream 45 in wine 282 soapy 187 in beer 294, 298 in cheese 147 in milk 144 solvent 268, 269 sour in dairy products 148 spicy in beer 294,301 sulphide in beer 294 sulphuric in cider 309 sulphury in wine 313 tallowy 155 in dairy products 158 violets in carrots 64 woody in meat 63 in wine 313 yeasty in beer 294 in milk 162 taint tests diagnostic 25-26 ethical considerations 24, 34-37 preventive 26-30 review 21-34 taint transfertests 26-30 taste see sensory description test methods see sensory test methods test procedures see sensory test procedures texture definition thiophenols 99 10I threshold acetaldehyde 250 2-acetyltetrahydropyridine 62 alcohols 210 aldehydes 196, 197 bromophenols 43 2-bromophenol 48 6-chloro-