I cannot tell you how many times we hear some wanker spewing ignorant information to impress someone or perhaps not want to admit they don't know something at a tasting room. Occasionally we have heard enough, drank enough, or are not being supervised and we engage the afore mentioned wanker.
Recently while out tasting through some new releases at a local winery, one of the customers asked the pourer if this particular winery had any wines under screwcap. The response from the tasting room staff got my attention, not only because it was wrong, but by the absolute certainty and disdain with which this opinion was dispatched.
So what was the response? - Not only do we not, we would never consider using scewcaps, as they 'choke' the wines and do not let them breath at all. They make the wine all funky and don't allow any aging at all.
What he was possibly referring to was post-bottling “reduction,” unpleasant off odors and flavors created by the mix of oxygen and sulfides.
Natural corks have been used to seal wine bottles for about 300 years. The application introduced the concept of “aged wines,” because of cork’s oxygen permeability. So the big problem is that Oxygen ingress is highly variable due to the varied properties of the natural nature of cork. The impact of oxygen transmission rates can significantly affect wine aroma and color which are influenced by oxygen exposure in the bottle. Too much oxygen decreases fruity aromas and increases oxidative aromas. New Zealand’s signature varietal Sauvignon Blanc is one of the most sensitive to oxygen, perhaps explaining those clever Kiwis’ early adoption of screwcaps. Red wines are less affected and probably why less are capped. Oh and by the way, a couple of our go to favorite reds are!