(NewWorldWinemaker) - The cat is out of the bag so to speak. It seems that not all tannins are created equal and quality differences between suppliers exist. Best you make sure you buy from a trusted supplier… I recently read an interesting article, published in a reputable scientific journal called: “Impact of exogenous tannin additions on wine chemistry and wine sensory character.” They analyzed the effects of a range of enological tannins in Merlot wine. First they analyzed how much of the product sold as tannin was indeed tannin.