Corked wine

Wine drinkers sometimes find that a bottle is corked. This means that a defective cork has leached trichloro-anisole, or TCA, into the wine. This compound ruins the wine, making it smell like wet cardboard. Some wine collectors report that as much as 20% of the bottles they open are corked, while others hardly ever encounter the problem. How would you account for the individual differences How could the problem of corked wines be solved ... 

Amon and coworkers (1986, 1989) analyzed 37 wines affected by cork taint, using gas-phase chromatography, equipped with an olfactometry system and coupled with a mass spectrometer. They analyzed the compounds most frequently found, both in corked wine and their respective corks. Their findings are shown in Figure 8.13. These same authors ran triangular tests with a panel of twelve tasters and found that the perception thresholds for these compounds in a non-aromatic, dry white wine were particularly low (Table 8.11). 

Table 8.13. Demonstration of the dual contamination of a red wine by the atmosphere in the winery and the cork (wines bottled on the same day with a single batch of corks, analysis carried out after 12 months, results in mg per bottle or per cork) (Chatonnet et al., 1994)...

A different example of the potential of GC-MS for the analysis of flavors and off-flavors is represented by a series of studies dealing with the characterization of volatile compounds in cork used for the production of wine stoppers [43-45]. The approach chosen for these investigations was the application of DHS for aroma sampling and the use of GC-MS for the analysis of the volatile components of different cork samples in various analytical problems (1) characterization of the volatile fraction in raw material (bark) and new and used cork wine stoppers [43], (2) characterization of volatile compounds produced by microorganisms isolated from cork [44], and (3) study of the effects of electron-beam irradiation on cork volatile compounds in a sterilization process [45]. 

During the 1960s, Americans lived in a lead-drenched society. They fueled their cars with leaded, antiknock gasoline. They ate food and their babies drank milk from lead-soldered cans. They stored drinking water in lead-lined tanks and transported it through lead or lead-soldered pipes. They squeezed toothpaste from lead-lined tubes and poured wine from bottles sealed with lead-covered corks. They picked fruit sprayed with lead arsenate pesticide and served it on lead-glazed dishes in houses painted and puttied with lead-based compounds. 

If winemakers corked their bottles like some people cork their flasks, there d be few oneophiles and we d probably judge good years for salad dressings rather than wines. You don t just take a new cork and stick it down into the neck of the flask, vial, or what have you. You must press the cork first. Then as it expands, it makes a very good seal and doesn t pop off. 

Formaldehyde analysis has been used to detect and measure oak extract in wines aged in wood cooperage and to correlate the amount of extract with the aging effect (27). Tannins and phenols of oak (and redwood and cork) are predominantly nonflavonoid-hydrolyzable tannins (Table XI), and they add to the otherwise relatively low and... 

Quality control audit of incoming bottling room supplies, such as filtration media (membranes), glassware, corks, screw caps in non-premium wineries, labels, foil capsules or sheets, wire hoods, and plastic or natural corks in sparkling wine operations Sanitation practices... 

Cork Finish Bottles. It is believed widely that corks in bottles tend to crack and leak air more easily when bottles are stored upright than when stored upside down or on their sides so that the cork remains in contact with wine. Although no definitive study of this has been reported, it is recommended that the practice be continued. 

After the white wine is bottled it should be stored with the bottles lying on their sides so that the corks stay damp and tight enough to prevent the ingress of air to the wine. The wine will be preserved best in a cool, quiet, dark environment. White wines are particularly sensitive to heat and sunlight. 

The quantity of wine for chemical analysis should be at least four bottles of about a litre each. Transparent bottles should be used and they should be rinsed first with water and then with the wine so that no trace of any substance previously present can remain. The bottles should be filled, carefully stoppered with new corks of good quality and provided with sealing-wax seals and with a label giving all the particulars necessary for the identification of the sample. Further, on a special sheet are given the name and address of the holder of the wine, the capacity of the casks or other vessels from which the sample is drawn and the extent to which they are filled, any production of scum (so-called " fleurs de vin ) being noted and, if possible, the type, place of origin and year of production of the wine itself. 

Chatonnet P, Bonnet S, Boutou S, Labadie M-D (2004) Identification and Responsibility of 2,4,6-Tribromoanisole in Musty, Corked Odors in Wine. J Agric Food Chem 52 1255... 

Similar concerns involve the plasticizers in plastic wine corks, due to the presence of phthalates however, any such concern seems to have been negated by the use of screw caps or glass stoppers. In any event, with these new closures one can avoid the unpredictable moldy off-flavor cork taint characterized by a set of undesirable smells and tastes, called "corked" or "corky," that can arise in any wine with traditional corks, irrespective of price and quality level. 

Tartrate, corresponding base of tartaric acid. The mixed potassium-sodium-salt is the famous tartrate (potassium bitartrate), which crystallizes on the cork of wine bottles (Seignette salt). 

Pressure has a dramatic affect on the solubility of gaseous solutes in liquid solvents. As pressure increases, the solubility of a gaseous solute in a liquid solvent increases. You have no doubt observed this phenomenon when opening a carbonated beverage. Have you noticed that when you open a bottle of champagne (or soda pop, or beer, or club soda), small bubbles of carbon dioxide gas start to form That pop you hear when removing the cork is caused by the escape of excess carbon dioxide gas from the bottle. When the gas escapes, the pressure in the container decreases. With less pressure, the solubility of the carbon dioxide dissolved in the wine decreases. As the carbon dioxide comes out of the solution, it forms those tiny (wonderful) little bubbles. Since solids and liquids are not very compressible, at least not compared to gases, pressure has very little effect on the solubility of solid and liquid solutes. 

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