Recently, melatonin (Mel) has been detected in wine, and as its quantity increases during alcoholic fermentation, yeasts are primarily responsible for its production during the process. L-tryptophan (L-Trp) is an indolic molecule that plays an important role as a precursor of a large amount of tryptamine molecules, including Mel. We propose a novel method for detecting Mel and other derived indole compounds directly on yeast cells based on the voltammetry of immobilized particles methodology. This will abridge and facilitate the detection of these highly conserved and electroactive molecules. Tafel and modified Tafel analyses have been used to distinguish among Mel, tryptophol, and indole-3-acetic acid. We obtained different voltammetry responses in various Saccharomyces strains treated with L-Trp, 5-hydroxytryptophan, and serotonin and without them. The different responses allowed us to assess the production of indole compounds from L-Trp and other precursors. The voltammetric changes in mutant strains with deleted genes of tryptophan metabolism were also tested.

This work was supported by Ministry of Education, Culture and Sport Projects AGL2013–47300-C3 and CTQ2014–53736-C3–2-P and PROMETEOII/2014/042 from the Spanish government and the Generalitat Valenciana, respectively. These projects are also supported by ERDF funds.

Peer reviewed