Effect of different nitrogen sources on melanoidin decolorization. Decolorization yield (), Biomass production (). The control flask does not contain any nitrogen sources. Test flasks contained different nitrogen sources in the medium at a level of 0.5% (w/v). Inoculated flasks were incubated at 45°C for 24 h. Error bars presented are mean values of ± standard deviation of triplicates of three independent experiments.