Complicated mixtures of organic substances with glass-like or solid-liquid properties. Resins that remain liquid after they come out are called balsam, hot hard resins (resins in the narrower sense) that harden in the air through the release of substances. The mostly intense and pleasant balsamic smell is caused by numerous essential oils, for example terpenes. Various resins, such as myrrh, were therefore already used in ancient times to flavour wine and other beverages. Probably the best-known resin-flavoured wine is the Greek retsina. Resin from the mastic tree is added to the Greek liquor ouzo. The Greek historian Herodotus (482-425 BC) reported that the Greeks chewed the dried resinous liquid that dripped from the bark of the mastic tree (as chewing gum, so to speak).
Most resins are found in conifers. They are obtained from plant or animal substances or are produced artificially. Of plant origin are, for example, gum arabic and starch, of animal origin albumin (from egg white), casein (from milk) and gelatine (from cartilage and bones). Synthetically produced resins include PVPP. Resins have the ability to polymerise. Due to their adsorptive effect, special synthetic resins are used for ion exchange in winemaking. This is used, for example, in fining (removal of colour defects), filtration (removal of bacteria and yeasts), and for the purpose of deacidification, acidification and removal of tartar.
Picture left: By Thomas Bresson - Own work, CC BY 3.0, Link
Centre image: By GeoTrinity - Own work, CC BY 3.0, Link
Image right: By Adrian Michael - Own work, CC BY-SA 3.0, Link
