Study On Fermentation And Recovery Of Natural Orange/yellow Pigments By Monascus

The Monascus pigment as a safe and natural food colorant is applied for a long history. The traditional product of Monascus pigment is a mixture of red, orange, yellow pigments and based on the red pigment. In the admixture of pigments, orange/yellow pigments on the senses are the best fresh and uniquely eye-catching pigments, which are worthy of studying and exploiting. This study was designed to screen of Monascus mutants with high orange/yellow pigment production, combine single factor and orthogonal experiment to improve the ability of this pigment production in solid-state fermentation(SSF) and extract orange/yellow pigments from two kinds of fermented products of fermentation liquor or red rice, which provided theoretical foundation for massively producing orange/yellow pigments. And the main results are as follow.Monascus sp. WM951 as original strain was selected from many Monascus strains in our laboratory, which was treated by a new technology, atmospheric and room temperature plasma(ARTP), to mutagenesis spore suspension of Monascus. The optimal irradiation time for the mutation was 90 s, at which the lethality rate of Monascus spore was 78%, and the mutation rate of the morphology was 14.2%, respectively. The mutant strain WM951M1 with a high yield of orange and yellow pigment was ultimately screened out. According to the full wavelength scanning results, the maximum absorption peak of pigments in the mutant strain appeared at 465 nm and 410 nm, indicating that the mutant strain mainly synthesized orange and yellow pigments. The color value of orange pigment and yellow pigment was 3620 U×g-1 and 3300 U×g-1 in SSF of WM951M1 at 30℃ for 240 h, which was 43% and 136% higher than that of the original strain, respectively.To improve the pigment production in SSF by Monascus sp. WM951M1, single-factor and orthogonal experiment were designed. The optimal fermentation conditions were as follows, incubation temperature of 29℃, inoculum size of 7%(v/w), 55 g material contained in 500 m L Erlenmeyer flask and initial moisture content of 37%. Under these optimized conditions the incubation was performed in constant temperature and humidity incubator for 240 h, in which the yellow pigment value was 4423 U×g-1 and it’s hue was 1.43, while the orange pigment value was 4813 U×g-1 and it’s hue was 1.59. It’s orange/yellow pigments had an increase of 229.7%、94.4%, which was a leading level.To obtain high pure-color pigment, we focused on extracting orange/yellow pigment from red rice, at which the optimal extraction conditions were explored. The extractant solvent was the mixture of extractant and water with the ratio of 6:4(v/v), and the ratio of material to liquor was 1:5(w/v). Under this extraction conditions, the extraction rate of orange/yellow pigment was 50.7% and 66.8%, respectively. Through analyzed qualitatively, the results showed that the isolated pigments were mainly yellow/orange pigments, and red pigment was still contained in red rice.The optimal conditions of treating mycelium, water phase and extraction phase were studied. In the case of adjusting the operating parameters, the use of disc centrifuges could separate mycelium, pigment-rich extract phase and no pigment water phase. The pigments of extraction phase were extracted into ethanol with multi-stage counter-current extraction techniques, the volume ratio of the liquid-liquid for 4:1(v/v), extracted stages of 3, extraction temperature of 60℃ and extraction time 30 min per level. Under these conditions, the orange/yellow pigment extraction rate were 91.21% and 95.92%. The ethanol solution containing orange/yellow pigments was concentrated, mixed with dextrin, dried for solid product of orange/yellow pigments. With analyzed by full wavelength scan and TLC, the results were mainly reflected that the solid product mainly contained orange/yellow pigments, but not containing the red pigment.