You are more in the right here than your brother; when buying wine at a restaurant you really just smell and taste the wine. If the wine smells and tastes fine to you, and you can’t pick up any cork taint, go ahead and approve it. Cork taint detection is very much as reliant upon our own individual sensory thresholds as it is upon the actual level of the “corked” compounds in the wine. Believe it or not, the “cork-taint” defect, attributable to, trichloroanisole (TCA) or related haloanisole compounds (molecules containing different numbers of halogen atoms, either chlorine or bromine), can manifest in the wine alone and may not actually be caused by the cork, or by the cork alone per se.
The haloanisole most commonly found in wine is TCA. It is widely known as the “cork-taint” compound, but contamination of wine during the production or cellaring process is also possible. There are other haloanisoles like PCA (pentachloroanisole) and TBA (tribromoanisole) which are biodegradation by-products of compounds that could be present in chlorine bleach, sanitizers, flame retardents and wood preservatives. Any of these can be present in the winery environment and though it’s unlikely that any of these things are getting into wine vats, mold spores that have interacted with these items could conceptually come into contact with the wine. These scenarios are quite unlikely but one that isn’t is the ubiquity of mold on barrels. Moldy barrels plus winery water that contains chlorine can be a TCA taint issue that is just waiting to happen.
Corks aren’t the only potential source of TCA in wines. The haloanisoles can be transferred into wine through a cellar’s atmosphere or by contact with contaminated materials from tank coatings, hoses, barrels, oak chips, filter pads, and additives such as bentonite. These smelly compounds (the haloanisoles which are often described as having “musty,” “moldy,” or “wet- cardboard-like” aromas) aren’t themselves transmitted from these sources into wine but are metabolic products of naturally-present fungi. For example, if certain fungus species come in contact with a chlorine molecule (in the winery’s water supply for instance) the fungus may metabolize (digest and spit out) trichloroanisole.
Interestingly, a cork may smell “tainted” and the wine below it might be just fine, or, better said the wine in the bottle may be below your TCA threshold. Especially in summertime, when warmer ambient temperatures mean that every aroma (good and bad ones alike) will be more apparent to your senses, be sure you sniff the wine itself, and not just the cork, to make sure you’re not buying a tainted bottle.