Handbook of Enology Volume 1 The Microbiology of Wine and Vinifications 2nd Edition Handbook of Enology Volume 1 The Microbiology of Wine and Vinifications 2nd Edition P. Ribereau-Gayon,´ D. Dubourdieu, B. Doneche` and A. Lonvaud 2006 John Wiley & Sons, Ltd ISBN: 0-470-01034-7 Handbook of Enology Volume 1 The Microbiology of Wine and Vinifications 2nd Edition Pascal Ribereau-Gayon´ Denis Dubourdieu Bernard Doneche` Aline Lonvaud Faculty of Enology Victor Segalen University of Bordeaux II, Talence, France Original translation by Jeffrey M. Branco, Jr. Winemaker M.S., Faculty of Enology, University of Bordeaux II Revision translated by Christine Rychlewski Aquitaine Traduction, Bordeaux, France Copyright 2006 John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wiley.com All Rights Reserved. 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Library of Congress Cataloging-in-Publication Data: Ribereau-Gayon,´ Pascal. [Traite´ d’oenologie. English] Handbook of enology / Pascal Ribereau-Gayon,´ Denis Dubourdieu, Bernard Doneche` ; original translation by Jeffrey M. Branco, Jr.—2nd ed. / translation of updates for 2nd ed. [by] Christine Rychlewski. v. cm. Rev. ed. of: Handbook of enology / Pascal Ribereau´ Gayon ... [et al.]. c2000. Includes bibliographical references and index. Contents: v. 1. The microbiology of wine and vinifications ISBN-13: 978-0-470-01034-1 (v. 1 : acid-free paper) ISBN-10: 0-470-01034-7 (v. 1 : acid-free paper) 1. Wine and wine making—Handbooks, manuals, etc. 2. Wine and wine making—Microbiology—Handbooks, manuals, etc. 3. Wine and wine making—Chemistry—Handbooks, manuals, etc. I. Dubourdieu, Denis. II. Doneche,` Bernard. III. Traite´ d’oenologie. English. IV. Title. TP548.T7613 2005 663.2—dc22 2005013973 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN-13: 978-0-470-01034-1 (HB) ISBN-10: 0-470-01034-7 (HB) Typeset in 10/12pt Times by Laserwords Private Limited, Chennai, India Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production. Contents Remarks Concerning the Expression of Certain Parameters of Must and Wine Composition vii Preface to the First Edition ix Preface to the Second Edition xiii 1 Cytology, Taxonomy and Ecology of Grape and Wine Yeasts 1 2 Biochemistry of Alcoholic Fermentation and Metabolic Pathways of Wine Yeasts 53 3 Conditions of Yeast Development 79 4 Lactic Acid Bacteria 115 5 Metabolism of Lactic Acid Bacteria 139 6 Lactic Acid Bacteria Development in Wine 161 7 Acetic Acid Bacteria 183 8 The Use of Sulfur Dioxide in Must and Wine Treatment 193 9 Products and Methods Complementing the Effect of Sulfur Dioxide 223 10 The Grape and its Maturation 241 11 Harvest and Pre-Fermentation Treatments 299 12 Red Winemaking 327 13 White Winemaking 397 14 Other Winemaking Methods 445 Index 481 Remarks Concerning the Expression of Certain Parameters of Must and Wine Composition UNITS more correct expression in milliequivalents per liter has not been embraced in France. The expres- Metric system units of length (m), volume (l) and sion of total and volatile acidity in the equivalent weight (g) are exclusively used. The conversion of weight of sulfuric acid has been used predomi- metric units into Imperial units (inches, feet, gal- nantly throughout these works. In certain cases, the lons, pounds, etc.) can be found in the following corresponding weight in tartaric acid, often used in enological work: Principles and practices of wine- other countries, has been given. making, R.B. Boulton, V.L. Singleton, L.F. Bisson Using the weight of the milliequivalent of the and R.E. Kunkee, 1995, The Chapman & Hall various acids, the below table permits the conver- Enology Library, New York. sion from one expression to another. More particularly, to convert from total acidity EXPRESSION OF TOTAL ACIDITY expressed in H2SO4 to its expression in tartaric AND VOLATILE ACIDITY acid, add half of the value to the original value (4 g/l H2SO4 → 6 g/l tartaric acid). In the other Although EC regulations recommend the expres- direction a third of the value must be subtracted. sion of total acidity in the equivalent weight of tar- The French also continue to express volatile taric acid, the French custom is to give this expres- acidity in equivalent weight of sulfuric acid. More sion in the equivalent weight of sulfuric acid. The generally, in other countries, volatile acidity is Desired Expression Known Expression meq/l g/l g/l g/l H2SO4 tartaric acid acetic acid meq/l 1.00 0.049 0.075 0.060 g/l H2SO4 20.40 1.00 1.53 1.22 g/l tartaric acid 13.33 0.65 1.00 g/l acetic acid 16.67 0.82 1.00 Multiplier to pass from one expression of total or volatile acidity to another viii Remarks Concerning the Expression of Certain Parameters of Must and Wine Composition expressed in acetic acid. It is rarely expressed and then divided by 17 to obtain a fairly good in milliequivalents per liter. The below table also approximation of the TAP. allows simple conversion from one expression to another. In any case, the determination of the Brix or TAP The expression in acetic acid is approximately of a must is approximate. First of all, it is not 20% higher than in sulfuric acid. always possible to obtain a representative grape or must sample for analysis. Secondly, although physical, densimetric or refractometric measure- EVALUATING THE SUGAR ments are extremely precise and rigorously express CONCENTRATION OF MUSTS the sugar concentration of a sugar and water mix- ture, these measurements are affected by other sub- This measurement is important for tracking grape stances released into the sample from the grape maturation, fermentation kinetic and if necessary and other sources. Furthermore, the concentrations determining the eventual need for chaptalization. of these substances are different for every grape This measurement is always determined by or grape must sample. Finally, the conversion rate physical, densimetric or refractometric analysis. of sugar into alcohol (approximately 17 to 18 g/l) The expression of the results can be given accord- varies and depends on fermentation conditions and ing to several scales: some are rarely used, i.e. yeast properties. The widespread use of selected degree Baume´ and degree Oechsle. Presently, two yeast strains has lowered the sugar conversion rate. systems exist (Section 10.4.3): 1. The potential alcohol content (titre alcoom´et- Measurements Using Visible raque potential or TAP, in French) of musts and Ultraviolet Spectrometry can be read directly on equipment, which is The measurement of optic density, absorbance, is graduated using a scale corresponding to 17.5 widely used to determine wine color (Volume 2, or 17 g/l of sugar for 1% volume of alcohol. Section 6.4.5) and total phenolic compounds con- Today, the EC recommends using 16.83 g/l as centration (Volume 2, Section 6.4.1). In these the conversion factor. The ‘mustimeter’ is a works, the optic density is noted as OD, OD 420 hydrometer containing two graduated scales: (yellow), OD 520 (red), OD 620 (blue) or OD 280 one expresses density and the other gives a (absorption in ultraviolet spectrum) to indicate the direct reading of the TAP. Different methods optic density at the indicated wavelengths. varying in precision exist to calculate the TAP Wine color intensity is expressed as: from a density reading. These methods take var- ious elements of must composition into account CI = OD 420 + OD 520 + OD 620, (Boulton et al., 1995). Or is sometimes expressed in a more simplified 2.