Smaller berries = better skin to fruit ratio = more tannin.(Warmer years normally produce small berries.) Petit Verdot and Cabernet Sauvignon have a thick skin and can extract plenty of tannins. Wine Tasting is fun so do not make it a complicated, scientific project. Down the road . https://Berger-Laustsen-2.Technetbloggers.de/electric-wine-opener-reasons-purchase-an-electric-wine-bottle-opener-1717623371