Genetic Systems for Condensed Tannin Biotechnology Abstract Condensed tannins (proanthocyanidins) are plant phenolic polymers with protein-binding, carbohydrate-binding, and antioxidant properties. Dietary condensed tannins deter some insects from feeding on crops, disrupt insect digestion and growth,1 and deter larger browsing and foraging animals.2 As well, the very high levels of condensed tannins found in tropical plant