Preliminary Study On Screening And Application Of High-yield Orange Pigment Monascus

Monascus has been used in China for thousands of years.It can produce monascus pigment,citrinin and other secondary metabolites after fermentation.In this study,high-yield orange pigment strain MPs-8 was isolated,purified and screened from red yeast rice,the effects of rice and bean dregs as substrate for MPs-8 fermentation products were studied,and the stability of pigments in different pH alcohol solutions and photostability in meat products were evaluated,the detection methods and the effects of different extraction methods on the extraction rate of citrinin in fermentation products were studied,the results are as follows:Eleven typical strains were isolated and purified from different kinds of red yeast rice.According to the product color value and HPLC detection results,the high-yield orange pigment strain Monascus Mps-8 was obtained.The effects of rice and adding 30%soybean dregs in rice on the solid fermentation products of Monascus Mps-8 were studied.It was found that the fermentation products of rice(sample A)were mainly orange pigments and the yield reached 55.87 mg/g,while the products of adding soybean dregs(sample B)in rice were mainly red pigments and the yield reached 21.84 mg/g,but orange pigment decreased significantly.The results showed that the addition of proper nitrogen could promote the transformation of orange pigments into red pigments.TLC and HPLC were used to detect citrinin and determine the minimum detection concentration of citrinin.It was found that the minimum detection concentration of citrinin detected by TLC was 100μg/mL.The minimum detection concentration of citrinin was 0.005 μg/mL by diode array detector and 0.001 μg/mL by fluorescence detection.The content of citrinin in the rice fermentation product of Monascus MPs-8 was 0.72mg/g.The effect of pH on the stability of the pigment alcohol solution in MPs-8 fermentation products was studied.It was found that orange pigment and red pigment were stable in the alcohol solution with pH=3.The red pigment was stable in the alcohol solution with pH=8,9 and 10.The orange pigment is stable in the alcohol solution with pH=11.The photostability of MPs-8 fermentation products in meat products was studied.It was found that the photostability of red pigment derivatives obtained by amination of orange pigment in meat products was better than that of red pigment.