Collective term for defects or undesirable and unacceptable faults in wine, which manifest themselves primarily through an unpleasant to disgusting odour and/or taste or "only" in appearance (haze, cloudiness, crystals, etc.). They are detected, among other things, during a wine evaluation and a wine assessment, whereby wines with certain faults or to a certain extent are dropped from the rating. A distinction is sometimes made between wine faults (wine defects) and wine diseases. The latter are changes in the wine caused by micro-organisms(bacteria, fungi, viruses), which can increase in intensity if appropriate countermeasures are not taken. Many of these defects and faults in wine can be prevented or at least reduced or in some cases subsequently eliminated by appropriate preservation and fining methods using suitable agents.
Whether a certain odour and taste is already perceived as a fault is subjective in some cases. This is because there are some borderline cases where a certain odour or taste is pleasant and positive for one person, but unpleasant or even faulty for another. Examples of this are the typical petrol tone of a Riesling or the earthy smell of a red wine, which is described as horse sweat. However, there are also objectively recognisable, generally valid defects that deviate from a certain standard. The spectrum ranges from barely perceptible or faintly perceptible to unpleasant and spoilt and also depends on experience and sensitivity. A good example is the notorious cork taint, which is recognised by experienced people even at the slightest level. With the right experience, wine faults can be recognised or identified quite accurately. This can also be learnt; various manufacturers offer aroma sets for this purpose:
In most cases, however, sensory judgement is not sufficient for accurate identification. The causes of wine defects can already occur during the growth of the grapes and then during the entire processing chain from the grape harvest to bottling, but also afterwards during bottle ageing. In most cases, these are chemical and microbiological processes triggered by microorganisms such as fungi or bacteria or complex reactions between different substances. Causes can also be of a physical nature, such as too much contact with oxygen.
The odour and taste of a wine is made up of many chemical compounds. The total extract of a quality wine is between 17 and 30 g/litre. The flavouring substances make up 0.8 to 1.2 g/l of this. The substances responsible for almost all wine faults are now known. These usually extremely small quantities are specified in milligrams (mg = thousandths), micrograms (µg = millionths) to nanograms (ng = billionths) per litre. In the latter case, this means a single grain of wheat out of ten tonnes of wheat. They are perceived above a certain quantity, which is referred to as the perception threshold:
Wine faults |
Substance |
Amount |
bitter almond note | Prussic acid | 0.04 mg |
Strawberry flavour | Furaneol | 30 to 40 ng |
foxy | Aminoacetophenone | 0.5 µg |
Cork flavour | Methoxy-dimethylpyrazine Tribromanisole (TBA) Trichloroanisole (TCA) |
2 to 4 ng 3 to 4 ng 1 to 5 ng |
Mice | Acetic acid ethyl ester and others | 0.1 to 1.6 µg |
Horse sweat | Etyhylcatechol (horse stable, sweat) Ethylguaiacol (cloves, tar) Ethylphenol (medicinal-pungent) |
50 µg 50 µg 300 to 600 µg |
Black curd, metallic | iron copper Zinc |
10 mg 2 mg 5 mg |
UTA (atypical age tone) | Aminoacetophenone | 0.5 µg |
The substances causing wine faults or defects can only be determined beyond doubt using analytical methods. One of these is chromatography (gas chromatography). PNA-FISH (Peptide Nucleic Acid Fluorescence In Situ Hybridisation) is a new method for the detection of microbiologically based wine defects. The most important factors in wine production are absolute cleanliness and sterility as well as (usually) the avoidance of oxidation (oxygen ingress). Many wine defects can be avoided by observing these measures, some of which are quite complex.
The list includes not only wine faults and defects, but also relatedg terms:
bottle sickness to Brettanomyces
Depot to frosty flavour
geranium to hydroxymethylfurfura
Aftertaste to reduction flavours
TDN to UTA
Three particularly recommendable books on this complex subject area, which have also been used as sources with the kind permission of the publishers/authors, are
Wine defects - Recognise, avoid, remedy
Österreichischer Agrarverlag Druck- und Verlags Ges.m.b.H. Nfg.KG, Leopoldsdorf
Dipl.-Ing. Dr Reinhard Eder (Editorial Director) and others.
Recognising wine defects - identification, avoidance, remedy
Eugen Ulmer KG 2007 / Dr Edmund Lemperle
Cellar management
Österreichischer Agrarverlag - 2001 Leopoldsdorf
HR Dipl.-Ing. Robert Steidl Dept. of Cellar Management / Dept. Enology
Federal College and Federal Office for Viticulture and Fruit Growing Klosterneuburg NÖ
Pictures
Nail varnish: Image by donations welcome on Pixabay
Grape: From Robert-Owen-Wahl on Pixabay
Böckser: From Capri23auto on Pixabay
Corker: From 445693 on Pixabay
Wine error set: © www.aromaster.com
In the past, you needed a wealth of encyclopaedias and specialist literature to keep up to date in your vinophile professional life. Today, Wine lexicon from wein.plus is one of my best helpers and can rightly be called the "bible of wine knowledge".
Prof. Dr. Walter Kutscher
Lehrgangsleiter Sommelierausbildung WIFI-Wien