Gordon Newton Johnson, Chris Alheit, the late, great Paul Pontalier of Château Margaux, Alfred Tesseron of Château Pontet‐Canet of Château Belgrave and other Dourthe properties, Jean‐Luc Columbo, Nicolas Joly, Sandro Bottega, Ernie Loosen, Raimund Prüm, José and Sebastien Zuccardi, Philip Tuck MW, Gordon Burns, and Evin Morrison of ETS Laboratories, Matthias Hüttl of LANXESS, Gordon Specht and Ann Dumond of Lallemand, Pascal Chatonnet, Gevork Arakelian, and Ken Walker. Finally, thanks to Nick Catley, Trevor Elliott and Hazel Tattersall for reviewing individual chapters.
Preface
Wines are produced today in over 65 countries, and it is often stated that production standards are higher than at any time in the 8000 or more years of vinous history. The consumer rightly expects any wine purchased to be of good quality, bearing in mind the price point, and free from fault, flaw, or taint. Wine critics, writers, producers, and retailers are all in the business of selling enjoyment and entertainment, for nobody has to drink wine – it is a beverage to be savoured. However, the incidences of faulty wines reaching the consumer are greater than would be regarded as acceptable in most other industries. It is claimed that such occurrences are less than was the case in recent recorded history, and it is true that the frequency of some faults, flaws, and taints being encountered in bottle (or other packaging) has declined in the last few decades. Gone are the days when a bottle of dry white Bordeaux would have more ‘struck‐match’ sulfur odours than the aromas of Sémillon or Sauvignon Blanc, and a white Bairrada exude the ‘Oloroso Sherry‐like’ aromas and bitter palate resulting from oxidation. Happily too, in recent years, there has been a considerable reduction in the occurrence of haloanisole contamination (often referred to as ‘cork taint’), which renders heavily affected wines undrinkable, having the musty odour of damp hessian or dry rot. However, incidences of certain faults and taints have increased, and issues that were once unheard of now affect many wines offered for sale. These include ‘reduced’ aromas, premature oxidation (premox), atypical ageing and, very much on the rise, smoke taint.
The reduction in the occurrence of some faults might have been expected with the increased sophistication and regulation of wine production, and the advance in scientific and technical knowledge of grape growers and winemakers. These, taken together with the utilisation of a vast array of high specification production equipment, might lead the consumer to believe that they are extremely unlikely to be faced with a faulty bottle of wine. This is sadly not the case. The increased incidence of some defects is, prima facie, surprising. However, the styles of wines that consumers want, or are perceived by the industry to want, have changed in the last 20 years or so. Grape harvests are often delayed until so‐called phenolic ripeness and, together with the effects of climate change, this has resulted in higher grape sugars, higher pH, and lower acidity. Each of these presents dangers. In the case of red wines, and particularly those at so‐called ‘entry‐level’, tannins are softer, and levels of residual sugar have often increased. Inexpensive wines are usually brought to the market very quickly, sometimes within a few months of harvest. Time is money, and there may be little time or budget for all desirable stabilisation procedures to take place. Finally, the consumer and especially the serious wine lover, wants wine to be a natural, agricultural product that has been turned into something wonderful by an artisan, not a scientist. Accordingly, many producers strive to make wine as ‘natural’ as possible, by reducing interventionist techniques and minimising chemical and biological additions, including those that may increase stability and prevent the onset of certain faults. It is also of concern that there is an increase in the incidence of mycotoxins in wines, due to their production by some of the microbial populations on vines. This is perhaps another consequence of climate change. Related off‐flavours, which were historically noted only occasionally, have been detected at a much higher frequency during the last 15 years.
This book provides a detailed examination and explanation of the causes and impact of the faults, flaws, and taints that may affect wines. As such, I believe that it will prove particularly valuable to winemakers, especially those at small, boutique wineries, wine technologists and quality control professionals. Wine critics, writers, educators, and sommeliers will also find the topics most relevant. With wine trade students and people venturing into the business of wine production in mind, the content is designed to be easily and speedily assimilated. The interested and knowledgeable wine‐loving consumer, including wine collectors and investors, will also find the book highly relevant and the basis for discussion at many tastings with like‐minded associates.
It is assumed that the reader has, at least, a basic knowledge of winemaking. Those who feel the need to brush up on the methods and techniques of wine production, from vine to bottle, are referred to ‘Wine Production and Quality 2nd Edition’ by Keith Grainger and Hazel Tattersall, also published by Wiley. However, this book is very suitable for those with limited scientific knowledge, and I have made every effort to maximise readability, with many anecdotes and expressed opinions, including my own. The chasm between general and scientific wine publications is both wide and deep, and I have attempted to bridge this as soundly as possible. There are several excellent books on viticulture and oenology, written in scientific language. Some of these are listed in the Further Reading. Alternatively, the easy to read articles and books penned by wine writers are seen by the scientific community as overflowing with anecdotes and lacking rigour. Of course, both approaches are valid, and I have made every effort to integrate them. I have tried to speak in terms that the general reader can understand. Although the number of studies and quality of research into chemical and microbiological faults in wine has increased considerably in the last couple of decades, most of this work remains within the confines of journals, which are largely unread outside of scientific and academic communities. On many occasions, results are inconclusive, conflicting, or the focus of some studies is seen as so narrow as to be of little relevance in the real world. Indeed many of the winemakers I have spoken to whilst researching this book have not been aware of the outcomes of recent research in important areas. Accordingly, there is still much misinformation and misunderstanding of the topics by producers, students and, of course, consumers.
Sections of individual chapters cover the science behind each fault, and for these, a very basic knowledge of organic chemistry and microbiology would be valuable. However, the scientifically challenged reader will find the text in includes helpful explanations, and the Glossary contains easy to understand definitions and descriptions of many scientific terms. I have included, at the end of each chapter, references to relevant publications and research papers (over 800 in total), concentrating on those in English and published within the last 20 years. I have also included references to earlier research that was particularly ground‐breaking. I have not included structural drawings, and there are very few chemical equations. I have not generally detailed isomers (isomers are where compounds have the same formula but differ from each other in the way the atoms are arranged). As the title of this work suggests, the focus is very much on practice – the book is certainly not aimed at the research scientist. In other words, I wish it to be a helpful manual for those who have little interest in the activities of the research lab, but to whom the excitement and challenges of the real world of wine are a way of life.
Keith Grainger
Saint‐André‐de‐Lidon
19 August 2020
Introduction
This book comprises a detailed examination of faults, flaws, and taints that can affect the quality and merchantability of wines. Technically, there is a distinction between a taint and fault that will be discussed in Chapter 1. However, wine consumers, merchants, and the press rarely observe such distinction, simply referring to the affected product as faulty. Some faults render affected wines unsaleable and undrinkable. Others that have a negative effect upon quality, enjoyment, or potential for ageing.
There are no reliable figures regarding the total global financial cost of faulty
