Wine Faults and Flaws. Keith Grainger

the purported environmental advantages of bulk wine shipping. A defective seal on an ISO tank or the use of a flexitank material that is highly permeable could allow oxygen ingress leading to degradation of the entire contents. Wines to be transported in bulk will require adjustment and stabilisation before their journey, and often again prior to packaging at destination – the latter operations being outside of the control of the producer, who may nevertheless bear the brunt of any fallout resulting from product deterioration, or the manifestation of faults or flaws. On the positive side, temperature variations during transport are very often less for wines in large tanks, and the standards of bottling at a dedicated plant at destination may be higher than those in some wineries.

1.4 The Possible Impact of Some Fault Compounds Upon Human Health

Most of the faults discussed in this book, however unpleasant they may be from an organoleptic point of view, are not generally harmful to human health, at least at the concentrations in which they may be found in wine. Wine has a low pH and pathogens harmful to humans will not generally grow in the product (although we should remember that every year somewhere in the world people die as a result of consuming ‘fake’ wine). There are, however, some compounds of microbiological origin that may be found in wine that have been shown to be potentially harmful to humans. The most important of these are biogenic amines, ochratoxin A and ethyl carbamate. Ethyl carbamate is classified as ‘a probable human carcinogen’ (Group 2A) by the International Agency for Research on Cancer (IARC) [6], and several countries have set limits for its concentration in wine. Biogenic amines are toxic at high concentrations, and some people have an intolerance at the levels very often found in wine. Ochratoxin A is a known carcinogen in some animals and a suspected human carcinogen by IARC (Group 2B) [6]; accordingly limits to its concentration in wine have been set by the European Commission (EC) for member states of the European Union (EU) at 2 μg/l [7]. In addition, some chemical compounds which may be found in wine can be harmful, particularly phthalates that can be hormone disruptors in humans. Their presence in wine is always due to contamination from an external source, such as the epoxy resin lining of concrete fermentation or storage vats. In a research paper published in 2014, Pascal Chatonnet et al. revealed that significant quantities of dibutyl phthalate (DBP) had been found in 59% of the (French) wines analysed [8]. Although, with the possible exception of biogenic amines that can have a ‘blood‐like’ odour and taste, the above compounds do not influence aroma or taste, their presence in wine other than at very low levels should be regarded as a fault; more of this will be discussed in Chapter 14.

      Of course ethanol, the alcohol of all fermented drinks, is a known carcinogen and is classified as ‘a human carcinogen’ (Group 1) by the IARC [6]. It is toxic if consumed in excess, and there are reported cases of death due to alcohol poisoning and other issues related to single acts of excessive consumption. Long‐term regular consumption of ethanol, other than at low levels, is also a causal factor in several carcinomas, liver diseases, and other health problems such as obesity, as wine lovers and imbibers of other alcoholic beverages are regularly made aware. Acetaldehyde is considered a fault in wine only if present in excessive amounts, which generally means having a negative impact upon aroma, but when associated with alcohol consumption is also classified as ‘a human carcinogen’ (Group 1) by the IARC [6].

1.5 Sulfur Dioxide and Other Possible Allergens

      Some individuals are allergic to grapes or alcohol. However, some compounds may be present in wine that may cause allergic reactions. The most important of these is sulfur dioxide (SO₂), which is generally added at several stages of the winemaking process for its antimicrobial and antioxidant properties. Even if none is added by the winemaker, most wine contains SO₂ as it is naturally formed by yeast during the alcoholic fermentation. Allergic reactions to this compound, which is also used as a preservative in a wide range of foods and drinks, are not uncommon, and individuals with asthma may suffer particularly adverse reactions. Many other people show an intolerance. The total SO₂ content of wine is regulated in the European Union (EU) and all major markets and any wine marketed that exceeds this must be considered as both faulty and illegal.

Certain processing aids, particularly fining agents, contain milk or egg products, which are allergens. For wines marketed in the EU, allergen labelling was made compulsory from 25 November 2005 under a European Commission Directive. Initially only the presence of sulfites/sulfur dioxide had to be declared on the label, for concentrations at or exceeding 10 mg/l. This threshold remains applicable. Most wines will contain in excess of this figure even if no SO₂ is added during the production process. In 2007 European Directive EC 2007/68 was issued, which provided for the mandatory labelling of further allergens – this directive has since been incorporated into EU Regulation No. 1169/2011 [9]. Due to objections from the wine industry this did not generally come into force until 2012. Insofar as wine is concerned, the only further allergens to be declared on the label are milk or egg products, if the concentration of either exceeds 0.25 mg/l. The current EU wine labelling regulations (EC) No: 2019/33 state the wording and form of allergen labelling information [10]. Wine marketed in the European Union remains exempt from the compulsory ingredients listing that was introduced for food products in 2011: EU Regulation No.: 1169/2011 [9].

1.6 Faults and Taints

      Generally in the food and drink industries, a distinction is conventionally made between the terms ‘fault’ and ‘taint’. A taint may be defined as an ‘unwanted and unacceptable odour or flavour; a contaminant derived from an external source including the environment and packaging’. Equipment used in wine production processes, additives, and processing aids (e.g. bentonite), the winery atmosphere, transport containers, and packing materials including cork bottle closures can be sources of taints. Rather simplistically, the ISO defines a taint as a ‘taste or odour foreign to the product originating from external contamination’ [11]. Conversely, a fault may be considered to be an internal chemically or microbiologically produced off‐odour, off‐flavour, or cause of product deterioration. Oxidation and the off‐flavours from fermentative sulfur compounds are examples of faults. Biological and enzymatic degradation of compounds such as fatty acids frequently result in off‐flavours. Whilst faults may be due to poor or careless winemaking, care and diligence throughout the production, and packaging processes are also necessary to minimise the risk of taints.

However, the technical distinction between ‘faults’ and a ‘taints’ is not always clear, and restricting the use of the words in a such narrow manner makes little sense. For example, so‐called ‘smoke taint’ affects grapes, being adsorbed onto the skin of berries and translocated to grapes via leaves. However, it is the compounds that are created (metabolised) during winemaking that give smoke‐taint associated off‐odours and flavours. The so‐called ‘rogue’ yeast Brettanomyces produces compounds that may give off‐odours and flavours, and the words contaminant and taint are often used in this regard. For example Manuel Malfeito‐Ferreira talks of the ‘horse sweat’ taint when reviewing the impact of Brettanomyces [12]. In a restaurant, the diner rejecting a wine that exudes the damp, musty odours of the TCA compound, always derived from an external source such as a cork closure or even the cellar atmosphere, will inform the sommelier or waiter that it is faulty (or corked), and is most unlikely to use the descriptor ‘tainted’. In fact, at low levels, TCA compounds will not actually taint a wine, but will strip it of fruitiness and result in tasting very flat. Accordingly, a wine contaminated with TCA, other than at miniscule levels of concentration, will not always be tainted, but will always be faulty. Further, many researchers use the word ‘taint’ in papers when discussing what are technically faults, as do many professional wine writers and authors. David Bird MW, speaks of ‘reductive taint’ in his book Understanding Wine Technology (3rd Edition), which is used by many wine students worldwide studying for the internationally recognised Diploma examination of the Wine and Spirit Education Trust [5]. Dr Eric Wilkes of the Australian Wine Research Institute (AWRI) refers to reduced aromas, oxidation, and Brettanomyces as taints [13]. Accordingly, I consider that the word ‘fault’ should