Cork taint is a broad term referring to an off-odor and off-flavor wine fault arising from the presence of 2,4,6-trichloroanisole (TCA), a chemical compound that represents one of the strongest off-flavors, and one "generated naturally in foods/beverages", in particular wines, that considerably reduce the quality of these products.
An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds, particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.
Anisole, or methoxybenzene, is an organic compound with the formula CH3OC6H5. It is a colorless liquid with a smell reminiscent of anise seed, and in fact many of its derivatives are found in natural and artificial fragrances. The compound is mainly made synthetically and is a precursor to other synthetic compounds. Structurally, it is an ether with a methyl and phenyl group attached. Anisole is a standard reagent of both practical and pedagogical value.
A wine fault is a sensory-associated (organoleptic) characteristic of a wine that is unpleasant, and may include elements of taste, smell, or appearance, elements that may arise from a "chemical or a microbial origin", where particular sensory experiences might arise from more than one wine fault. Wine faults may result from poor winemaking practices or storage conditions that lead to wine spoilage.
The odor detection threshold is the lowest concentration of a certain odor compound that is perceivable by the human sense of smell. The threshold of a chemical compound is determined in part by its shape, polarity, partial charges, and molecular mass. The olfactory mechanisms responsible for a compound's different detection threshold is not well understood. As such, odor thresholds cannot be accurately predicted. Rather, they must be measured through extensive tests using human subjects in laboratory settings.
Alternative wine closures are substitute closures used in the wine industry for sealing wine bottles in place of traditional cork closures. The emergence of these alternatives has grown in response to quality control efforts by winemakers to protect against "cork taint" caused by the presence of the chemical trichloroanisole (TCA).
1-Octen-3-ol, octenol for short and also known as mushroom alcohol, is a chemical that attracts biting insects such as mosquitoes. It is contained in human breath and sweat, and it is believed that insect repellent DEET works by blocking the insects' octenol odorant receptors.
Ann C. Noble is a sensory chemist and retired professor from the University of California, Davis. During her time at the UC Davis Department of Viticulture and Enology, Noble invented the "Aroma Wheel" which is credited with enhancing the public understanding of wine tasting and terminology. At the time of her hiring at UC Davis in 1974, Noble was the first woman hired as a faculty member of the Viticulture department. Noble retired from Davis in 2002 and in 2003 was named Emeritus Professor of Enology. Since retirement she has participated as a judge in the San Francisco Chronicle Wine Competition.
Alkylpyrazines are chemical compounds based on pyrazine with different substitution patterns. Some alkylpyrazines are naturally occurring highly aromatic substances which often have a very low odor threshold and contribute to the taste and aroma of various foods including cocoa, baked goods, coffee and wines. Alkylpyrazines are also formed during the cooking of some foods via Maillard reactions.
An odor or odour is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and many animals can perceive via their sense of smell. An odor is also called a "smell" or a "scent", which can refer to either an unpleasant or a pleasant odor.
2-Methylisoborneol (MIB) is an irregular monoterpene derived from the universal monoterpene precursor geranyl pyrophosphate. MIB and the irregular sesquiterpene geosmin together account for the majority of biologically-caused taste and odor outbreaks in drinking water worldwide. MIB has a distinct earthy or musty odor, which most people can easily smell. The odor detection threshold of MIB is very low, ranging from 0.002 to 0.02 micrograms per liter in water. MIB is also a factor in cork taint in winemaking.
Pentachloronitrobenzene, typically abbreviated PCNB, is a registered fungicide formally derived from nitrobenzene. It is either an off-white or yellow solid, depending on its purity, with a musty odor.
2,4,6-Tribromoanisole (TBA) is a chemical compound that is a brominated derivative of anisole. It is one of the chemicals responsible for cork taint.
Nomacorc is a company producing engineered synthetic corks for wine bottles. Nomacorc closures are co-extruded to manage the oxygen transfer rate for wine, reducing 2,4,6-trichloroanisole (TCA), more commonly known as cork taint.
Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4. The chemistry of wine and its resultant quality depend on achieving a balance between three aspects of the berries used to make the wine: their sugar content, acidity and the presence of secondary compounds. Vines store sugar in grapes through photosynthesis, and acids break down as grapes ripen. Secondary compounds are also stored in the course of the season. Anthocyanins give grapes a red color and protection against ultraviolet light. Tannins add bitterness and astringency which acts to defend vines against pests and grazing animals.
Off-flavours or off-flavors are taints in food products caused by the presence of undesirable compounds. They can originate in raw materials, from chemical changes during food processing and storage, and from micro-organisms. Off-flavours are a recurring issue in drinking water supply and many food products.
Adsorbable organic halides (AOX) is a measure of the organic halogen load at a sampling site such as soil from a land fill, water, or sewage waste. The procedure measures chlorine, bromine, and iodine as equivalent halogens, but does not measure fluorine levels in the sample.
Gas chromatography-olfactometry (GC-O) is a technique that integrates the separation of volatile compounds using a gas chromatograph with the detection of odour using an olfactometer. It was first invented and applied in 1964 by Fuller and co-workers. While GC separates volatile compounds from an extract, human olfaction detects the odour activity of each eluting compound. In this olfactometric detection, a human assessor may qualitatively determine whether a compound has odour activity or describe the odour perceived, or quantitatively evaluate the intensity of the odour or the duration of the odour activity. The olfactometric detection of compounds allows the assessment of the relationship between a quantified substance and the human perception of its odour, without instrumental detection limits present in other kinds of detectors. Compound identification still requires use of other detectors, such as mass spectrometry, with analytical standards.
Smoke taint is a broad term for a set of smoke imparted compounds found in affected wines, constituting a wine fault. Increasing incidences of smoke tainted wines are an important issue, given the recent occurrences of wildfires or bushfires in wine grape producing regions during the growing seasons. Examples of wildfires resulting in smoke tainted wines include the fires in South Africa in late 2017, October 2017 Northern California wildfires, the 2019–20 Australian bushfire season, and the 2020 Glass Fire in Northern California.
