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WINE ANALYSIS AND PRODUCTION
WINE ANALYSIS AND PRODUCTION
The Chapma1l 6 ... Hall Enology Library
Wine Analysis and Production by Bruce W. Zoecklein, Kenneth C. Fugelsang, Barry H. Gump, and Fred S. Nury
Principles and Practices of Winemaking by Roger B. Boulton, Vernon 1. Singleton, Linda F. Bisson, and Ralph E. Kunkee
Forthcoming Titles Winery Utilitites by David R. Storm Wine Microbiology by Kenneth C. Fugelsang
WINE ANALYSIS AND PRODUCTION Bruce W. Zoecklein Virginia Polytechnic Institute & State University, Blacksburg
Kenneth C. Fugelsang California State University at Fresno
Barry H. Gump California State University at Fresno
Fred S. Nury California State University at Fresno
SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
An direction: Andrea Meyer, emDASH inc. Cover design: Saeed Sayrafiezadeh, emDASH inc.
Copyright © 1995 Springer Science+Business Media Dordrecht Originally published by Chapman & Hali in 1995 Softcover reprint ofthe hardcover Ist edition 1995
Ali rights reserved. No part of this work covered by the copyright hereon may be reproduced or used in any form or by any means-graphic, electronic, or mechanical, including photocopying, recording, taping, or information storage and retrieval systems-without the written pennission of the publisher.
1 2 3 4 5 6 7 8 9 10 XXX 01 00 99 97 96 95
Library of Congress CataIoging-in-Publication Data
Wine analysis and produetion I Bruee W. Zoecklein ... [et al.]. p. em.
Ineludes bibliographieal referenees and index.
1. Wine and wine making-Analysis. 1. Zoecklein, Bruee W. TP548.5.A5W54 1994 663' .2-de20 94-17776
CIP
British Library CataIoguing in Publication Data available
ISBN 978-1-4757-6980-7 ISBN 978-1-4757-6978-4 (eBook) DOI 10.1007/978-1-4757-6978-4
CONTENTS
PREFACE xvii
1 INTRODUCTION 3 Overview of Wine Analysis-Gordon H. Bums, Director, ETS
Laboratories, St. Helena, CA 3 Reasons for Analysis 3 Common Analytical Components 3 Current Analytical Techniques 5 Future Analytical Techniques 7 A Technical Revolution in Winemaking-Lisa Van der Water,
Director, the Wine Lab, Napa, CA, and Pacific Rim Enology Services, Blenheim, New Zealand 9
Relating pH and S02 9 Grapes Are Important 10 Attention on Yeasts 10 Spoilage Microbes 12 Looking to the Future 13 Wine and Health-It Is More Than Alcohol-Carlos J. Muller, Director,
Enology Program, California State University, Fresno, CA 14 Antioxidants 15
v
vi Contents
Coexistence (Synergism) of Alcohol and Wine Antioxidants 19 Salicylic Acid 26 Conclusion 28
2 APPliCATION OF SENSORY EVALUATION IN WINE MAKING 30 Susan E. Duncan, Assistant Professor, Department of Food Science and
Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA 30
Overview of Sensory Evaluation 30 Standardization of Sensory Evaluation 31 Sensory Panelists 34 Methods of Sensory Evaluation 39 Principal Component Analysis 46 Summary 48
3 GRAPE MATURI'IY AND QUALITY 53 Wine Quality 53 Maturity Sampling 58 Fruit Quality Evaluation 62 Pesticides 68 Sensory Considerations as an Indicator of Grape Maturity and Quality 68 Soluble Solids in Winemaking 70 Laboratory Measurements of Soluble Solids 72 Analysis 75
4 HYDROGEN ION (pH), AND FIXED ACIDS 76 Organic Acid Content of Wine 76 Interaction of Hydrogen and Potassium Ions and Titratable Acidity 77 Hydrogen Ion Concentration and Buffers 80 Sample Preparation and Reporting TA Results 82 Adjustments in Titratable Acidity and pH 83 Legal Considerations 87 Sensory Considerations 88 Analysis 88
5 CARBOHYDRATES 89 Reducing Sugars (Hexoses) 89 Pentoses 92 Sucrose 92 Polysaccharides (and Associated Instabilities) 92 Mute Production 94 Soluble Solids vs. Reducing Sugar Values 94 Analysis of Reducing Sugars 94 Invert Sugar Analysis 96 Analysis 96
6 ALCOHOL AND EXTRACT 97 Yeast Metabolism 97 Ester Formation 106
Contents vii
Methanol 107 Ethanol Production 108 Determination of Alcohol Content 109 Extract 113 Analysis 114
7 PHENOliC COMPOUNDS AND WINE COLOR 115 Representative Grape and Wine Phenols 115 Grape Growing and Processing Considerations 127 Factors Contributing to Wine Color and Color Stability 134 Oxidation 138 Oak Barrel Components 142 Evaluation of Color by Spectrophotometry 146 Analysis 151
8 NITROGEN COMPOUNDS 152 Nitrogen Compounds of Grapes and Wines 152 Effect of Vineyard Practices on Nitrogen Compounds 154 Wine Proteins 157 Prefermentation Processing Considerations 158 Fermentation and Post-fermentation Processing Considerations 158 Effect of Protein on Wine Stability 163 Processing Considerations and Protein Stability 164 Methods for Evaluation of Protein Stability 165 Determination of Total Protein and Nitrogen-Containing
Compounds 166 Analysis 167
9 SULFUR-CONTAINING COMPOUNDS 168 Sulfate (S04 -2) 168 Sulfite (SO~-) 170 Hydrogen Sulfide (H2S) 170 Organic Sulfur-Containing Compounds 173 Vineyard Management 175 Hydrogen Sulfide and Mercaptans in Wine 175 Analysis 177
10 SULFUR DIOXIDE AND ASCORBIC ACID 178 Sulfur Dioxide as an Inhibitor of Browning Reactions 179 Compounds That Bind with Sulfur Dioxide 180 Distribution of Sulfite Species in Solution 182 Bound and Free Sulfur Dioxide 183 Sulfur Dioxide in Wine Production 185 Sources of Sulfur Dioxide 187 Analysis of Free and Total Sulfur Dioxide 189 Ascorbic Acid 190 Analysis 191
viii Contents
11 VOIATILE ACIDITY 192 Microbiological Formation of Acetic Acid 192 Acetate Esters 196 Sensory Considerations 197 Reduction of Volatile Acidity 197 Analytical Methods for Volatile Acidity 198 Analysis 198
12 METALS, CATIONS, AND ANIONS 199 Copper 200 Iron and Phosphorus 202 Aluminum 203 Lead 204 Metal Removal 206 Fluoride 207 Analysis of Metals 208 Analysis 208
13 SORBIC ACID, BENZOIC ACID, AND DIMETHYLDICARBONATE 209 Sorbic Acid 209 Benzoic Acid 212 Dimethyldicarbonate 213 Analytical Determination of Sorbic and Benzoic Acids and
Dimethyldicarbonate 214 Analysis 215
14 OXYGEN, CARBON DIOXIDE, AND NITROGEN 216 Redox Potentials in Wine Systems 216 Oxygen 218 Acetaldehyde 221 Carbon Dioxide and Nitrogen 222 Use of Gases 224 Measurement of Carbon Dioxide 227 Analysis 227
15 TARTRATES AND INSTABILITlES 228 Potassium 228 Calcium 230 Bitartrate Stability 230 Methodology for Estimating Cold Stability 234 Correction of Bitartrate Instability 236 Calcium Tartrate Stability 240 Analysis 241
16 FINING AND FINING AGENTS 242 Principles of Fining 242 Fining and Wine Stability 244 Summary of Important Considerations in Fining 245 Bentonite 245 Polysaccharides 250
Contents ix
Carbons 251 Silica Dioxide 252 Protein Fining Agents 253 Yeast Fining 260 Polyvinylpolypyrolidone 260 Tannin 261 Metal Removal 262 Riddling Aids 262 Utilization of Enzymes in Juice and Wine Production-Katherine G.
Haight, Research Associate, Viticulture and Enology Research Center, Fresno, CA 264
Glucanases 264 Pectinases 265 Macerating Enzymes 266 Ultrafiltration 269 Future Developments 269 Summary 270 Procedures 271
17 WINERY SANITATION 272 Water Quality 273 Preliminary Cleaning 273 Cleaners (Detergents) 274 Sanitizers 275 Cleaning and Sanitation Monitoring 278 Analysis 279
18 MICROBIOLOGY OF WINEMAKING 280 Molds 280 Yeasts 281 Wine Bacteria 290 Lactic Acid Bacteria 292 Controlling Microbial Growth in Wine (A Summary) 298 Procedures 302
19 CORK 303 Cork Microbiology 304 Identity and Properties of Odor-Active Metabolites 304 Preparation of Cork for Shipment 307 Analysis 309
20 LABORATORY PROCEDURES 310
APPENDIX I. TABLES OF CONSTANTS, CONVERSION FACTORS 517
APPENDIX II. LABORATORY SAFElY 536
BffiLIOGRAPHY 541
INDEX 609
LIST OF LABORATORY
PROCEDURES
Component Method Reagent/purpose Page
Acetaldehyde Aroma screen Sulfite binding 328 Spectrometry (VIS) Enzyme analysis 329 Gas Chromatography 330 Titrametric Sulfite binding 330
Acetic acid Gas chromatography 331 HPLC Grape Inspection 333 Spectrometry (VIS) Enzyme analysis 335 Titrametric Distillation/ Cash still/ 336
Markham still Acetic acid bacteria Isolation and identification Microbiological method 351 Active AMYL alcohol Gas chromatography Component of fusel oils 340 Alcohol Various methods 340 Alpha-amino nitrogen Spectrometry (VIS) TNBS method 340 Ammonia pH meter Ion selective electrode 342 Amorphous materials Visual Diagnosis protein & phenols 343/323 Anthocyanins (total) Spectrometry (UV) Estimation in mg/L 343 Arginine (FAN) Spectrometry (VIS) TNBS method 344 Aroma Sensory Juice preparation 344
Sensory Alternative procedure 345
x
List of Laburatury Procedures xi
Component Method Reagent/purpose Page
Asbestos Microscopic Methylene blue 346/322 Bacteria/yeast Media Isolation and cultivation 346 Benzoic acid HPLC Includes sorbic acid 355
Spectrometry (UV) 357 Bitartrate (stability) Mixed methods Concentration 359
Product Calculation
Bitartrate (stability) Electrical Change in conductivity 359 Conductance
Visual Freeze test 360 Botrytis (mold) Spectrometry (VIS) Laccase 361 Brettanomyces Gas chromatography Determination of marker 363
( 4ethylphenol) compound °Brix Hydrometry Soluble solids 366/482
Refractometry 366/485 Calcium Atomic absorption 366
Ion selective electrode Potential related to ion 368 concentration
Calcium oxalate Microscopic Sediment in wine 369/319 Calcium tartrate Microscopic Sediment in wine 369/319 Carbohydrates HPLC 370 Carbohydrates Titrametric Reducing sugars 372 Carbon dioxide Physical method Carbodoser 372
Titrametric Enzyme analysis 372 Catalase Differentiation Acetics vs lactates 374/351 Cell counting Microscopic Yeast and bacteria 374 Cellulose Microscopic-chemical Diagnosis of fibrous 379/322
materials Chill haze Visual Protein-tannin stability 379/360 Chlorine (residual) Visual qualitative test Iodide plus starch 379
Visual qualitative test Silver nitrate 380 Citric acid HPLC 381/447
Paper chromatography 381/439 Spectrometry (VIS) Enzyme analysis 381
Color Spectrometry (VIS) Hue and intensity (tint and 382 density)
Spectrometry l0-0rdinate method 383 Copper Atomic absorption 385
Spectrometry (VIS) Diethyldithio carbamate 387 Visual qualitative test Copper casse determination 389/326
Cork Quality control testing Microbiological, physical, 389 chemical & sensory
Cork dust (lignin) Microscopic diagnostic test of sediment 391/392/ 321/395
Crystalline deposits Microscopic-chemical Diagnosis bitartrate & 395/319 tartrate
Cyanide Visual inspection Hubach test papers 395
xii List of Laburatory Procedures
Component Method Reagent/purpose Page
Dekkera Yeast identification Diagnostic 399/346 Diacetyl Spectrometry (VIS) Indicator of MLF 399 Dimethyl dicarbonate Gas chromatography 402 Ethanol Ebulliometry 404
Gas chromatography 407 Hydrometry Distillation 409 HPLC Grape inspection 411/333 Titrametric Dichromate 411 Visible spectrometry Dichromate 414
Ethyl acetate Gas chromatography Wine quality 415/422 Ethyl carbamate Gas chromatography mass 415
spectrometry Ethylphenol Gas chromatography Metabolite from 417/363
brettanomyces/ dekkera Extract Specific gravity 417
Brix hydrometer 419 Nomographs Rapid estimation 420
Fibrous materials Microscopic---chemical Diagnosis cellulose & 420/322 asbestos
Flavonoids Spectrometry (UV) Estimation 420/452 Spectrometry (VIS) Folin-Ciocalteu 420/455
Fluoride pH meter Ion selective electrode 420 Fructose Titrametric Reducing sugar 422/474/477
procedures HPLC 422/370 Spectrometry (VIS) Enzyme procedure 422/473
Fumaric acid HPLC 422/447 Fuse! oils Gas chromatography 422 Galacturonic acid HPLC Fruit quality 423/447 Glucans Visual Rapid diagnosis 423/324 Gluconic acid HPLC Fruit quality 423/447 Glucose Titrametric Reducing sugar 424/474/477
procedures HPLC 424/370 Spectrometry (VIS) Enzyme procedure 424/473
Glycerol HPLC Fruit quality 424/333 Spectrometry (VIS) Enzyme analysis 424
Hubach Visual Cyanide analysis 426/395 Hybrid wine Fluorescence Presence of hybrid varieties 426 Hydrogen ion (pH) pH meter 426 Hydrogen sulfide Sensory screen Copper and cadmium 428
sulfate Hydroxy cinnamates spectrometry (UV) Absorbance units or as 429/452
(total) caffeic acid equivalents Iodine Spectrometry (VIS) Residual oxidants 430 Iron Atomic absorption 431
Visual qualitative test Ferric casse 432/326 Spectrometry (VIS) Thiocyanate ion 432
List of Laboratury Procedures xiii
Component Method Reagent/purpose Page
Iso-amyl alcohol Gas chromatography 434/422 Iso-butyl alcohol Gas chromatography 434/422 Laccase Spectrometry (VIS) Syringaldazine 434/361 Lactic acid HPLC 434/447
Paper chromatography 434/439 Spectrometry (VIS) Enzyme analysis 434
Lactic acid bacteria Isolation and identification Microbiological method 351/436 Lead Atomic absorption Electrothermal vaporization 436 Malic acid Spectrometry (VIS) Enzyme analysis 438
HPLC 439/447 Paper chromatography 439
Malolactic Paper chromatography 439 fermentation (MLF)
Mannitol salt Differentiation hetero- 442/346 from homo-fermentative lactic acid bacteria
Mercaptans Sensory scan Copper sulfate 442/428 Metal instabilities VISUal Rapid diagnosis copper & 442/326
iron Methanol Gas chromatography 442/422 Microorganisms Plating and physiological Yeasts & bacteria 442/374
isolation & tests identification
Microorganisms Microscopic Yeast 442/374 microscopic cell counting
Mold Spectrometry Botrytis 442/361 Monoterpenes Spectrometry Fruit maturity 442/508 Nitrate pH meter Ion selective electrode 443 Nitrogen Spectrometry (VIS) Coomassie blue 444
Titrametric Formol method 445 Non-flavonoids Spectrometry (VIS) Folin-Ciocalteu 446/455 Nonsoluble solids VISUal Suspended solids 446 Organic acids HPLC Acids in juices & wines 447 Oxidative casse Visual Oxidative potential 450 Oxygen Dissolved oxygen meter O2 electrode 450 Pectins/ gums Visual estimation Rapid diagnosis 452/324 pH Instrumental Hydrogen ion 452/426
concentration Phenols Spectrometry (UV) Absorbance units 452
(estimation) Spectrometry (VIS) Folin-Ciocalteu 455 Titrametric Permanganate index 458 Visual Fe(II) ammonium sulfate 459
qual test Visual Folin-Ciocalteu qual test 460/323
:xiv List of Laboratury Procedures
Component Method Reagent/purpose Page
Phosphorus Atomic absorption Molybdic acid 460 Pigments HPLC & spectrometry 462/452 Polysaccharides Visual Pectins and glucans 463/324 Potassium Atomic absorption 463
Flame emission 464 Ion selective electrode 466
Proline Spectrometry (VIS) Ninhydrin/formic acid 467 n-Propyl alcohol Gas chromatography 468/422 Protein Spectrometry (VIS) Coomassie blue 469/444 Protein/ phenols Visual Amido black 10-B protein 469/323
stain (estimation) Visual Eosin Y protein stain 469/323
(estimation) Protein stability Visual examination Ammonium sulfate 469
(saturated) test Visual examination Bentotest 469 Visual examination Ethanol precipitation 470 Visual examination Heat test 470 Nephelometry or visual TCA precipitation 471
examination Visual examination Tannic acid precipitation 472
Reducing sugar Visual (clinitest) Rapid estimation 473 Spectrometry (VIS) Enzyme analysis 473 Titrametrlc Lane-Eynon 474 Titrametrlc Rebeline (gold coast) 477 Titrametrlc Invert sugar 479
Residual oxidants Titrametrlc/ spectrometry Residual chlorine and 480/379/ (VIS) iodine 380/430
Sodium Atomic absorption 480 Flame emission 481
Soluble solids Hydrometry °Brix, °balling, °baume, 482 ochsle
Refractometry Refractive index 485 Sorbic acid Spectrometry (VIS) Distillation-chemical 486
reaction Spectrometry (UV) Distillation (direct) 488 Spectrometry (UV) Extraction (direct) 489 HPLC 491/355
Spectral evaluation Spectrometry (UV) (VIS) 491/452 (pigments)
Stain Visualization Nigrosin 491/378/346 (morphological differentiation)
Visual (bacterial Gram 491/346 differentiation)
Visual (viable yeast) 491/346 Starch VISUal Diagnostic test 491/325
List of Laboratory Procedures xv
Component Method Reagent/purpose Page
Succinic acid HPLC 491/447 Paper chromatography 491/439
Sugar (reducing- Titrametric Hydrolysis/titration 491/479 Sulfur dioxide Spectrometry (VIS) Enzyme analysis 491
Titrametric Iodine (Ripper) 493 Titrametric Iodate (Ripper) 496 Titrite (rapid estimation) 497 Titrametric NaOH (aeration-oxidation) 497 Titrametric NaOH (Monier-Williams) 500
Tannin (total) Spectrometry (VIS) 502 Tartaric acid HPLC 503/447
Paper chromatography 503/439 Spectrometry (VIS) Metavanadate (carbon) 504 Spectrometry (VIS) Metavanadate (ion 506
exchange) Tartrate deposits Microscopic Potassium bitartrate or 508/319
calcium tartrate Atomic absorption Potassium or calcium 508/463/366
analysis Terpenes Spectrometry (VIS) Fruit maturity/quality (Cash 508
or Markham still) Titratable acidity Titrametric Sodium hydroxide 511 Titratable acidity Titrametric AOAC procedure 511 Trichloroanisol Sensory Cork defect 513/389 Urea Spectrometry (VIS) 513
Spectrometry (VIS) Enzyme analysis also 514 ammonia
Volatile acidity Titrametric Cash/Markham still 515/336 distillation
Yeast isolation & Visual Brettanomyces 515/346 identification
Visual Zygosaccharomyces 515/346 Yeast viability Microscopic cell counting Ponceau S 516/346
Microscopic cell counting Methylene blue 516/346
PREFACE
Winemaking as a form of food preseIVation is as old as civilization. Wine has been an integral component of people's daily diet since its discovery and has also played an important role in the development of society, religion, and culture. We are currently drinking the best wines ever produced. We are able to do this because of our increased understanding of grape growing, biochemistry and microbiology of fermentation, our use of advanced technology in production, and our ability to measure the various major and minor components that comprise this fascinating beverage.
Historically, winemakers succeeded with slow but gradual improvements brought about by combinations of folklore, obseIVation, and luck. However, they also had monumental failures resulting in the necessity to dispose of wine or convert it into distilled spirits or vinegar. It was assumed that even the most marginally drinkable wines could be marketed. This is not the case for modem producers. The costs of grapes, the technology used in production, oak barrels, corks, bottling equipment, etc., have increased dramatically and continue to rise. Consumers are now accustomed to supplies of inexpensive and high-quality varietals and blends; they continue to demand better. Modem winemakers now rely on basic science and
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Preface xvii
the systematic application of their art to produce products pleasing to the increasingly knowledgeable consumer base that enjoys wine as part of its civilized society.
The process of making wine involves a series of concerns for the grower, as well as the winemaker. The first concerns are viticultural, including delivery of sound, high-quality fruit at optimal maturity. Upon arrival at the winery, fruit quality is assessed, the grapes are processed, and fermentation is begun. Almost immediately, and in many instances simultaneously, chemical and microbiological stability of the young and/or aging wine becomes important. Finally, problems occur on occasion requiring utilization of remedial techniques to produce an acceptable product.
Production considerations serve as the framework in organizing this book. Within each chapter is information culled from the authors' collective years of experience, as well as from the literate wine community around the world. These chapters provide numerous practical, as well as fundamental, insights into the various aspects of the process. Winemakers will benefit from these insights while still maintaining (and gaining further insight into) their own.
Analytical techniques have become valuable tools of modem winemakers wishing to better understand their product. These analytical tools are another major feature of this text. The authors have gathered numerous procedures commonly used for grape, juice, and wine analysis. These procedures are presented as they are generally practiced in the industry around the world. We have formatted them into an easy-to-follow recipestyle to make them more useful to the winery technician. Our procedures provide instructions for preparing required reagents, stains, and media, and then outline the analyses in detail. To make these procedures more accessible, we have gathered them into a single chapter at the end of the "text" chapters. In addition to the "standard" laboratory procedures we have included a section of rapid "diagnostic" tests to assist in identifying problems encountered during winemaking. Several frequently used conversion and correction tables have also been collected into one section for the reader's convenience. Finally, we have provided some information on the safety aspects of the various reagents employed in conducting the laboratory analyses.
In developing material for this text, the authors have emphasized analyses as they would be carried out in a production laboratory. Realizing that different laboratories have different analytical capabilities, personnel, and equipment, we have in many instances provided several different approaches to the same analysis. Throughout this book we have given special attention to practical considerations and their importance in the total spectrum of winery operations. We have done the same with the laboratory
xviii Preface
procedures. It is the authors' wish that the book's format will satisfy the interests of laboratory personnel as well as winemakers. It is assumed that the reader has some basic preparation in the fields of chemistry and microbiology. A novice reader would be advised to acquire a basic textbook in quantitative analysis for descriptions of fundamental laboratory skills.
In writing this text we not only surveyed the literature of the winemaking world, but have solicited direct assistance from several guest authors. To help present the subject of laboratory chemical and microbiological measurements from both the historical and future perspective, we have selections by Gordon Burns, President of ETS Laboratory (St. Helena, CA), and Lisa Van de Water, Director of The Wine Lab (Napa, CA) and Pacific Rim Oenology Services (Blenheim, New Zealand). The issue of the health aspects of wine has never been a more important subject than it is today. To provide a perspective on this subject, Dr. Carlos Muller, Director of the Enology Program at California State University (Fresno, CA) has contributed a Chapter.
A rational approach to the uses and benefits of sensory analysis is always a complement to the subject of laboratory measurements. The sensory organs are, for the most part, our most sensitive analytical tool for monitoring certain wine components and microbiological processes. A chapter on sensory techniques is offered by Dr. Susan Duncan of the Department of Food Science and Technology, Virginia Polytechnic Institute (Blacksburg, VA). Finally, in adding a current perspective to the use of enzymes in juice and wine processing, we have solicited the efforts of Katherine Haight, Research Associate at the Viticulture & Enology Research Center (Fresno, CA). We are greatly appreciative of the efforts of these contributors, who have added an extra dimension to this text.
WINE ANALYSIS AND PRODUCTION
