Abstract:Orange Monascus pigments were produced by a two-stage fermentation process under pH 3 with Monascus ruber M7，followed by the purification of pigments by a fractional crystallization method.The purified orange Monascus pigments，along with amino acids，were used as precursors for the semi-synthesis of amino acidderived red Monascus pigments in vitro based on the aminophilic reaction.Results suggested that in the range of 300 nm-600 nm，the pigments had only one absorption peak and the λmaxwas approximately 472 nm，indicating that this pigment product was dominant with orange Monascus pigments，with a yield of（7.9±0.2）×104U/L.The following fractional crystallization step significantly increased the purity of orange Monascus pigments.After adding 0.5 volume of water to 70% ethanolic pigment extract，（0.63 ± 0.04）g of crystallized orange Monascus pigments were obtained with high purity from 1 L fermentation medium，and no citrinin was detected.The crystallized orange Monascus pigments mainly comprised two orange compounds，rubropunctatin and monascorubrin.Trp-and Glu-derived red Monascus pigments were successfully synthesized with the purified orange Monascus pigments by aminophilic reaction，and there were no obvious differences in the efficiency of converting orange Monascus pigments to the Trp-and Glu-derived red Monascus pigments.