During the processing, the increase in the phenolic compounds can increase tissue browning in some products (Tomás-Barberán and Espín, 2001). Phenolic compounds are the substrates of oxidative enzymes (PPO and POD). PPO can oxidize several substrates, including dopamine (Yang et al., 2000). The phenolic compounds may be involved in the growth regulation of potato tubers, as well as in the resistance mechanisms to diseases and insects, and in the metabolism of plants submitted to physiological, or mechanical stresses. Dao and Friedman (1992) reported that phenolic concentrations varied between 100 and 900mg dopamine 100g-1 of potato (wet weight), showing that the phenolic concentrations found in the present work were within the variation limits and were a non-desirable characteristic, as phenolic compounds were the substrates of oxidative enzymes (PPO and POD) responsible for the enzymatic browning of potatoes genotypes.