Chemistry enology handbook stabilization treatment wine

This book, written by experts, aims to provide a detailed overview of recent advances in oenology. Book chapters include the latest progress in the chemistry and biochemistry of winemaking, stabilisation, and ageing, covering the impact of phenolic compounds and their transformation products on wine sensory characteristics, emerging non-thermal technologies, fermentation.

Handbook of Enology, Volume 2. As an applied science, Enology is a collection of knowledge from the fundamental sciences including chemistry, biochemistry, microbiology, bioengineering, psychophysics, cognitive psychology, etc. The approach used in the Handbook of Enology is thus the same.

It aims to provide practitioners, winemakers, technicians and enology students. The Handbook of Enology Volume 2: The Chemistry of Wine Stabilization and Treatments uniquely combines chemical theory with the descriptions of day-to-day work in the latter stages of winemaking from clarification and stabilization treatments to ageing processes in vats and barrels.

The expert authors discuss: Compounds in wine, such as. Handbook of Enology, The Chemistry of Wine. Wine Chemistry and Biochemistry. Authors: M.

Victoria Moreno-Arribas, Carmen Polo. The aim of this book is to describe chemical and biochemical aspects of winemaking that are currently being researched.

This line of reasoning lead to the description of the antioxi- dant related chemical properties of this compound in the same chapter as well as an explanation of adjuvants to sulfur dioxide: sorbic acid antisep- tic and ascorbic acid antioxidant. In addition, the on lees aging of white wines and the result- ing chemical transformations cannot be separated from vinification and are therefore also covered in Volume 1.

Finally, our understanding of pheno- lic compounds in red wine is based on complex chemistry. All aspects related to the nature of the Preface to the First Edition xi corresponding substances, their properties and their evolution during grape maturation, vinification and aging are therefore covered in Volume 2. These works only discuss the principles of equipment used for various enological operations and their effect on product quality. For example, temperature control systems, destemmers, crushers and presses as well as filters, inverse osmosis machines and ion exchangers are not described in detail.

Bottling is not addressed at all. An in-depth description of enological equipment would merit a detailed work dedicated to the subject. Wine tasting, another essential role of the winemaker, is not addressed in these works.

Many related publications are, however, readily available. Finally, wine analysis is an essential tool that a winemaker should master. It is, however, not covered in these works except in a few particular cases i.

The authors thank the following people who have contributed to the creation of this work: J. Casas Lucas, Chapter 14, Sherry; A. Brugi- rard, Chapter 14, Sweet wines; J. Maujean, Chapter 14, Champagne; C. Poupot for the preparation of material in Chapters 1, 2 and 13; Miss F. Luye- Tanet for her help with typing. They also thank Madame B. Masclef in particu- lar for her important part in the typing, preparation and revision of the final manuscript. The Handbook has apparently been popular with students as an educational reference book, as well as with winemakers, as a source of practical solu- tions to their specific technical problems and sci- entific explanations of the phenomena involved.

It was felt appropriate at this stage to prepare an updated, reviewed, corrected version, including the latest enological knowledge, to reflect the many new research findings in this very active field.

The outline and design of both volumes remain the same. Some chapters have changed relatively little as the authors decided there had not been any sig- nificant new developments, while others have been modified much more extensively, either to clarify and improve the text, or, more usually, to include new research findings and their practical applica- tions.

Entirely new sections have been inserted in some chapters. We have made every effort to maintain the same approach as we did in the first edition, reflecting the ethos of enology research in Bordeaux. We use indisputable scientific evidence in microbiology, biochemistry, and chemistry to explain the details of mechanisms involved in grape ripening, fermen- tations and other winemaking operations, aging, and stabilization. The aim is to help winemakers achieve greater control over the various stages in winemaking and choose the solution best suited to each situation.

Quite remarkably, this scientific approach, most intensively applied in making the finest wines, has resulted in an enhanced capac- ity to bring out the full quality and character of individual terroirs. Scientific winemaking has not resulted in standardization or leveling of quality. On the contrary, by making it possible to correct defects and eliminate technical imperfections, it has revealed the specific qualities of the grapes harvested in different vineyards, directly related to the variety and terroir, more than ever before.

Interest in wine in recent decades has gone beyond considerations of mere quality and taken on a truly cultural dimension. This has led some people to promote the use of a variety of tech- niques that do not necessarily represent significant progress in winemaking. Some of these are sim- ply modified forms of processes that have been known for many years. Others do not have a suf- ficiently reliable scientific interpretation, nor are their applications clearly defined. In this Hand- book, we have only included rigorously tested techniques, clearly specifying the optimum con- ditions for their utilization.

As in the previous edition, we deliberately omitted three significant aspects of enology: wine analysis, tasting, and winery engineering. In view of their importance, these topics will each be covered in separate publications. The authors would like to take the opportunity of the publication of this new edition of Volume 1 to thank all those who have contributed to updating this work: — Marina Bely for her work on fermentation kinetics Section 3.

Casas Lucas for the paragraph on Sherry Section Yet the role of yeasts in alcoholic fermentation, particularly in the transformation of grapes into wine, was only clearly established in the middle of the nineteenth century. The ancients explained the boiling during fermentation from the Latin fervere, to boil as a reaction between substances that come into contact with each other during crushing.

In , a Dutch cloth merchant, Antonie van Leeuwenhoek, first observed yeasts in beer wort using a microscope that he designed and produced. He did not, however, establish a rela- tionship between these corpuscles and alcoholic fermentation. It was not until the end of the eigh- teenth century that Lavoisier began the chemical study of alcoholic fermentation. According to Fabroni, this material, comparable to the gluten in flour, was located in special utricles, particularly on grapes and wheat, and alcoholic fermentation occurred when it came into contact with sugar in the must.

In , a French physicist named Charles Cagnard de La Tour proved for the first time that the yeast was a living organism. According to his findings, it was capable of multiplying and belonged to the plant kingdom; its vital activities were at the base of the fermentation of sugar-containing liquids. The German naturalist Schwann confirmed his the- ory and demonstrated that heat and certain chem- ical products were capable of stopping alcoholic fermentation. He named the beer yeast zucker- pilz, which means sugar fungus—Saccharomyces in Latin.

In , Meyen used this nomenclature for the first time. This vitalist or biological viewpoint of the role of yeasts in alcoholic fermentation, obvious to us today, was not readily supported. Liebig and certain other organic chemists were convinced that chemical reactions, not living cellular activity, were responsible for the fermentation of sugar.

In his famous studies on wine and beer , Louis Pasteur gave definitive credibility to the vitalist viewpoint of alcoholic fermentation. He demonstrated that the yeasts responsible for spontaneous fermentation of grape must or crushed grapes came from the surface of the grape; he isolated several races and species.

He even conceived the notion that the nature of the yeast carrying out the alcoholic fermentation could influence the gustatory characteristics of wine. He also demonstrated the effect of oxygen on the assimilation of sugar by yeasts.

Louis Pasteur proved that the yeast produced secondary products such as glycerol in addition to alcohol and carbon dioxide. Since Pasteur, yeasts and alcoholic fermen- tation have incited a considerable amount of research, making use of progress in microbiology, biochemistry and now genetics and molecular biology.

In taxonomy, scientists define yeasts as unicel- lular fungi that reproduce by budding and binary fission. Certain pluricellular fungi have a unicellu- lar stage and are also grouped with yeasts. Yeasts form a complex and heterogeneous group found in three classes of fungi, characterized by their reproduction mode: the sac fungi Ascomycetes , the club fungi Basidiomycetes , and the imper- fect fungi Deuteromycetes.

The yeasts found on the surface of the grape and in wine belong to Ascomycetes and Deuteromycetes. The haploid spores or ascospores of the Ascomycetes class are contained in the ascus, a type of sac made from vegetative cells.

Asporiferous yeasts, incapable of sexual reproduction, are classified with the imper- fect fungi. In this first chapter, the morphology, repro- duction, taxonomy and ecology of grape and wine yeasts will be discussed.

Cytology is the morphological and functional study of the struc- tural components of the cell Rose and Harrison, The yeast cell contains cellular envelopes, a cytoplasm with various organelles, and a nucleus surrounded by a membrane and enclosing the chromosomes. Figure 1. Like all plant cells, the yeast cell has two cellular envelopes: the cell wall and the membrane. The periplasmic space is the space between the cell wall and the membrane.

The cytoplasm and the membrane make up the protoplasm. The term protoplast or sphaeroplast designates a cell whose cell wall has been artificially removed. In order to take advantage of these properties, the winemaker or enologist must have a profound knowledge of these organelles. It essentially consists of polysaccha- rides.

It is a rigid envelope, yet endowed with a certain elasticity. Its first function is to protect the cell. Protoplasts placed in pure water are immediately lysed in this manner. Cell wall elasticity can be demonstrated by placing yeasts, taken during their log phase, in a hypertonic NaCl solution. The cell wall appears thicker and is almost in contact with the membrane. The cells regain their initial form after being placed back into an isotonic medium. On the contrary, it is a dynamic and multifunctional organelle.

Its composition and functions evolve during the life of the cell, in response to environmental factors. In addition to its protective role, the cell wall gives the cell its particular shape through its macromolecular organization. It is also the site of molecules which determine certain cellular interactions such as sexual union, flocculation, and the killer factor, which will be examined in detail later in this chapter Section 1. Finally, a number of enzymes, generally hydrolases, are connected to the cell wall or situated in the periplasmic space.

Their substrates are nutritive substances of the environment and the macromolecules of the cell wall itself, which is constantly reshaped during cellular morphogenesis. Chitin represents a minute part of its composi- tion. The most detailed work on the yeast cell wall has been carried out on Saccharomyces cere- visiae —the principal yeast responsible for the alcoholic fermentation of grape must. It can be chemically fractionated into three categories: 1. It has very few branches.

Its degree of polymerization is Under the electron microscope, this glucan appears fibrous. It ensures the shape and the rigidity of the cell wall.

It is always connected to chitin. It has very few branches, like the preceding glucan. It has an amorphous aspect under the electron microscope. This knowledge can be used to contribute to a better definition of the quality of grapes and wine, a greater understanding of chemical and microbiological parameters, with the aim of ensuring satisfactory fermentations and predicting the evolution of wines, and better mastery of wine stabilization processes. As a result, the purpose of this publication is to guide readers in their thought processes with a view to preserving and optimizing the identity and taste of wine and its aging potential.

This third English edition of The Handbook of Enology , is an enhanced translation from the 9th French edition, and is published as a two-volume set describing aspects of winemaking using a detailed, scientific approach. The authors, who are highly-respected enologists, examine winemaking processes, theorizing what constitutes a perfect technique and the proper combination of components necessary to produce a quality vintage.

They also illustrate methodologies of common problems, revealing the mechanism behind the disorder, thus enabling a diagnosis and solution.

Volume 2: The Chemistry of Wine and Stabilization and Treatments looks at the wine itself in two parts. Part One analyzes the chemical makeup of wine, including organic acids, alcoholic, volatile and phenolic compounds, carbohydrates, and aromas.

Part Two describes the procedures necessary to achieve a perfect wine: the clarification processes of fining, filtering and centrifuging, stabilization, and aging.