Smaller berries = better skin to fruit ratio = more tannin.(Warmer years look after produce small berries.) Petit Verdot and Cabernet Sauvignon have a thick skin and can extract a tannins. Wine Tasting is fun so do not make it a complicated, scientific venture. https://objectstorage.ap-singapore-1.Oraclecloud.com/p/Lxv2x8a_ll5eGLlIrorSNNJeRdWzoDBmU7SpdntZcMzPTnnsqeLzThUAB5UVoMRK/n/axqjqojndoew/b/Ruou-tay/o/44TamquantrongcuaviecluachonlyvaphukienthichhopkhithuongthucRuouJohnnieWalkerGoldLabel.docx.html