Do wine bottles screw-capped rather than corked alter the flavor of character of the wine?

No, the closure of a wine bottle does not directly influence the taste. In fact, some winemakers bottle the same wine in different closures to give consumers some choice and the wines are still identical. However... using a screwcap greatly lessens the chance that a wine will develop a bottle flaw. Particularly, a screw-capped wine, or a wine with a synthetic cork, is not at risk for "cork taint." The causes of cork taint are boring, but it can only happen with a corked wine. It is the formation of either Trichloroanethole or Tribromoanethole. The first is detectable at several parts per billion, the second at several parts per trillion and they both create a bit of a musty smell. Also, corks can, if wine is not stored properly or not opened properly, perforate into the wine, ruining its flavor. There is plenty of debate over other differences between closure methods, but they are probably negligible. lamorindawinesociety.com