The growth of L. plantarum and S. cerevisiae in orange juice decreased the Eh of the medium by ca.200 and 250 mV, respectively (Fig. 1). The reducing rate increased after 24 and 45 h for S. cerevisiae and L. plantarum, respectively. This decrease in Eh values during the growth of microorganisms could have been caused by the uptake of oxidizing compounds such as oxygen from the medium, and the production of metabolites with reducing characteristics in the juice