Now would be a good time to introduce some of the key players in this story, in an attempt to make frighteningly chemical-sounding names understandable to a broader audience. First, we have polyphenols. These are a group of compounds that are vitally important in wine, and more specifically red wines. The name stems from the basic building block of this class of chemicals, which is the phenol group. This is a specific chemical structure that consists of a benzene ring with various additions, and it’s highly reactive. It likes to stick to other things, and an important property of phenolic compounds is that they associate spontaneously with a wide range of compounds, such as proteins and other phenolics, by means of a range of non-covalent forces (for example, hydrogen bonding and hydrophobic effects).