its not screwcaps on wine bottles that turn wine but how long ago the bottle was first opened, better to buy a bottle and have it opened at the table,if for some reason you dont finish it(i realise thats possible) you can always take it with you,it would be better for those that only wanted one glass, sometimes a free one! if the bar/cafe owners used wine from boxes as no air gets in when its poured,by the way does anyone know the best price for a bottle of yakut.