ENOLOGICAL CHEMISTRY Wine Is the Friend of the Wise Man and the Enemy of the Drunkard
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ENOLOGICAL CHEMISTRY Wine is the friend of the wise man and the enemy of the drunkard. It is bitter and useful like the advice of the philosopher; it is permitted to the gentleman and forbidden to the idiot. It lures the stupid into the fog and guides the wise toward God. Avicenna (980e1037) ENOLOGICAL CHEMISTRY Written and Edited by JUAN MORENO AND RAFAEL PEINADO Dpto. Quı´mica Agrı´cola y Edafologı´a, Universidad de Co´rdoba, Co´rdoba, Spain Translated by ANNE MURRAY AND IAIN PATTEN AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD PARIS SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Academic Press is an imprint of Elsevier Academic Press is an imprint of Elsevier 32 Jamestown Road, London NW1 7BY, UK 225 Wyman Street, Waltham, MA 02451, USA 525 B Street, Suite 1800, San Diego, CA 92101-4495, USA First edition 2012 Copyright Ó 2012 Elsevier Inc. All rights reserved Originally published in Spanish under the title Quı´mica Enolo´gica, by Juan Moreno and Rafael Peinado. A. Madrid Vicente, Ediciones, 2010. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone (+44) (0) 1865 843830; fax (+44) (0) 1865 853333; email: [email protected]. Alternatively, visit the Science and Technology Books website at www.elsevierdirect.com/rights for further information Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN : 978-0-12-388438-1 For information on all Academic Press publications visit our website at www.elsevierdirect.com Typeset by TNQ Books and Journals Printed and bound in United States of America 12 13 14 15 10 9 8 7 6 5 4 3 2 1 Dedication To our families and loved ones, for the time we could not dedicate to them whilst writing this book. Thank you for your endless encouragement, patience, and understanding. The authors. This page intentionally left blank Contents Preface ix About the Authors xi 13. Acid-Base Equilibria in Wine 195 14. Buffering Capacity of Wines 223 1. The Vine 1 15. Precipitation Equilibria in Wine 253 2. Composition of Grape Must 13 16. Changes in Acidity after 3. Must Aromas 23 Fermentation 271 4. Composition of Wine 41 17. Redox Phenomena in Must and Wine 289 5. Polyphenols 53 18. The Colloidal State 303 6. Sugars: Structure and Classification 77 19. Wine Colloids 323 7. Sugars in Must 95 20. Inorganic Material and Metal Casse 355 8. Carboxylic Acids: Structure and Properties 109 21. Chemical Aging 375 9. Grape Acids 121 22. Aging 389 10. The Relationship Between Must 23. Biological Aging 405 Composition and Quality 137 11. The Transformation of Must into Index 417 Wine 157 12. Nitrogen Compounds 183 vii Preface Enology has traditionally been considered breadth of knowledge that has been accumu- both a science and an art. Progress in the lated in the field. To this end, enology can field has been linked to the work of a core now be studied as a university degree. This group of professionals who have produced volume is the product of more than 10 years’ empirical evidence essentially by trial and experience in teaching the chemistry of wine error. These insights, however, have often to students on the degree course in enology failed to reach an audience sufficiently at the University of Co´rdoba in Spain. The wide to drive innovation in those countries authors draw on material from lectures with a strong winemaking tradition. Nowa- and laboratory sessions to provide an up- days, a wealth of scientific evidence is avail- to-date review of the subject that will be of able to support continued innovation and use to students, professionals, and all those development, and these developments will who want to increase their knowledge of be essential to successfully overcoming the wine science. The content is designed to be challenges faced by the wine industry. accessible to anyone with a solid foundation Modern enology is now inconceivable in chemistry. without specialist training to cover the ix This page intentionally left blank About the Authors Juan Moreno was born in Co´rdoba, Spain Rafael Peinado was born in Co´rdoba, in 1955. He holds a degree in chemistry and Spain, in 1975. He holds degrees in chem- a PhD in science from the University of istry (1998) and enology (2001), and he Co´rdoba, where he is currently a tenured completed his doctoral studies at the Univer- professor. Prof. Moreno has conducted exten- sity of Co´rdoba in 2004. His early research sive enological research since 1983 and has interests were the biological deacidification published over 86 articles, 64 of which have of must and wine and the development of appeared in international journals; he has a new cell immobilization system. He is also presented over 100 papers at confer- currently working on the characterization ences worldwide. His research interests of musts made from different varieties of include the chemistry of grape ripening, the sun-dried grapes and studying the antioxi- characterization and fermentation of musts, dant properties of these musts and vinifica- the biological aging of Andalusian wines, tion sub-products. He has published more and the production of sweet wines from than 35 articles in international journals raisined grapes. As part of his work at the and made numerous presentations at University of Co´rdoba, he has taught general national and international congresses. He chemistry to students on the degree course in combines his research activities with chemistry since 1996, and since 1999, he has lecturing on food and technology science, taught wine chemistry to students on the enology, and forest engineering. degree course in enology and general chem- istry, and to forest engineering students. xi This page intentionally left blank CHAPTER 1 The Vine OUTLINE 1. Biological Cycles of the Vine 1 3. Chemical Composition of the Fruit 6 1.1. The Growth Cycle 2 3.1. Composition of the Stalk 6 1.2. The Reproductive Cycle 3 3.2. Composition of the Seeds 7 2. Morphology of the Grape Clusters 4 3.3. Composition of the Skin 8 3.4. Composition of the Pulp 9 2.1. The Stem or Stalk 4 3.5. Composition of the Must 11 2.2. The Grape Berry 5 1. BIOLOGICAL CYCLES OF THE VINE Vines are herbaceous or sarmentose shrubs. Their leaves are simple and more or less palmate or lobulate in shape, and they have tendrils that grow in the opposite direction. Their flowers have five petals joined at the apex which are grouped in narrow panicles. Commonly, the flowers are unisexual. The fruit is an oligospermic berry with a spherical or ovoid shape that contains pear-shaped seeds and a soft pulp. ThevinebelongstotheVitaceae family, which includes a dozen genera. Among these are Ampelopsis and Parthenocissus, which include wild vines, and Vitis, which is responsible for all table and wine grape varieties. The genus Vitis contains around 40 species, the most important being Vitis vinifera or the European species, which is used in the production of high-quality wines, and the American species Vitis rupestris, riparia, berlandieri, labrusca, etc., which have been used as rootstocks and direct-producing hybrids. Within each species, there are varieties that only conserve their characteristics by vegetative propaga- tion, and can therefore be considered as clones. There are 6800 known varieties of V. vinifera alone, although no more than 100 are used to produce the most recognizable wines worldwide. Enological Chemistry. DOI: 10.1016/B978-0-12-388438-1.00001-7 1 Copyright Ó 2012 Elsevier Inc. All rights reserved. 2 1. THE VINE WINTER DORMANCY GROWTH CYCLE GROWTH OF THE VEGETATIVE ORGANS WITHERING WEEPING BUD BURST TERMINATION OF GROWTH LEAF FALL JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER FLOWERING VERAISON RIPENESS GROWTH OF THE REPRODUCTIVE ORGANS RIPENING REPRODUCTIVE CYCLE FIGURE 1.1 Growth and reproductive cycle of the vine. As vines are perennial plants, they undergo characteristic morphological changes with the seasons. Throughout each yearly cycle, the vine undergoes: • The growth and development of the vegetative organs (shoots, leaves, tendrils, and roots), its survival through the accumulation of reserves (withering), and the acquisition of latency by the buds. This is the growth cycle. • The growth and development of reproductive organs (inflorescences, flowers, and berries) and their maturation. This is the reproductive cycle. The morphological cycle of the vine has particular characteristics known as phenological events. In chronological order these are weeping, bud burst, flowering, fruit set, ripening, and leaf fall. There are two clearly distinguishable periods in the yearly cycle of the vine, namely winter dormancy, during which no morphological changes occur and which extends from leaf fall until bud burst, and active growth, which begins with bud burst and ends with leaf fall. During the period of active growth, the organs are constructed, the seeds and berries form, and the materials necessary for survival accumulate in the living parts of the plant.