Formation of the Comutagenic Beta-Carboline Norharman in a Simple Tryptophan-Containing Model System at Low Temperature (40°C-80°C)

Abstract

The formation of the comutagenic tryptophan derivate norharman in heat-processed food is a well known phenomenon. As a first step to investigate the possible formation of norharman during food storage particularly in regard to fortified food we developed a model system and studied the non-enzymatic formation of the comutagen at temperatures below 100°C. With standard conditions (4h, 80°C) iron and copper (Fe²⁺/Cu²⁺) was required for the formation of norharman. Addition of glucose to the reaction mixture increased the norharman formation and a plateau was reached with 400 μM tryptophan. Decreasing the reaction temperature to 40°C led to a significant formation of norharman after 72 hours of incubation indicating that the formation of norharman can take place at temperatures that are close to ranges occurring during food storage.