SAN FRANCISCO — Don’t judge a wine by its cover. In a survey of the chemistry and flavor of pinot noir and chardonnay, consumers couldn’t discern wines capped with natural corks from screw caps, scientists reported March 25 at the spring meeting of the American Chemical Society. The results suggest that the way its bottle is stopped has little if any effect on a wine’s flavor. “Wine quality should really be judged by the wine, not the cork,” said Michael Qian of Oregon State University in Corvallis, who led the research. “The right kind of screw cap is just as good as a cork, or even better, because it is more consistent.”