Extraction Of Monascus Pigment And Preparation Of Water-soluble Monascus Yellow Pigment

Monascus pigment is the natural colorant produced by monascus,it is widely used in the production of wine,vinegar,red fermented bean curd,braised pork,sausage,candy,jam,fruit juice drinks,pastries and other food coloring,it has thousands of years of application history in China.Monascus pigment has been favorable for overseas markets with its features of pH stability,good heat resistance,good lightfastness,high security and so on.In terms of food coloring,the yellow pigment is a principal varieties of food coloring,the yellow tone is relatively softer and more seductive compared with other hues,so consumers have a strong desire to purchase it.The main monascus pigment produced by monascus is the alcohol-soluble monascorubrin and rubropunctatin,the water-insoluble nature hinders the further application of the monascus pigment.Changing the alcohol-soluble nature of monascus pigment,improving the solubility and colorimetric performance,has become the direction of the further development of the monascus pigment.This paper explores the preparation of water-soluble monascus yellow pigment by experiment,and draws the following conclusions:Choose alcohol as the solvent for extracting alcohol-soluble monascus pigment,and I explore the conditions for extracting monascus pigment from the dynamic perspective.The optimum conditions for extracting monascus pigment are alcohol concentration of 85%,extracting temperature of 60?,solid-liquid ratio of 1:15,pH 4 and extracting time of 90min.The method of preparation of water-soluble monascus yellow pigment by ethanol extraction is to extract the alcohol-soluble monascus pigment from the red yeast rice,reduce monascus pigment with sulfur compounds,which can reduce cyclic carbonyl in the rubropunctatin and monascorubrin molecular to hydroxyl group,then alkaline hydrolysis to open the lactone key in the molecule and generate polycarboxylates,so we can obtain the good water-soluble monascus yellow pigment.When we use the method,selecting the concentrated sulfuric acid as sulfonating agent is better than sodium sulfite in the transformation effect.The optimal conditions for conversion of alcohol-soluble monascus pigment into water-soluble monascus yellow are sulfonated reaction temperature of 70?,sulfonated reaction time of 1.5h,alkaline hydrolysis temperature of 80?,alkaline hydrolysis time of 6h,and the color value of the water-soluble monascus yellow pigment we obtain is 2735u/g.The method of preparing water-soluble Monascus yellow pigment by alkaline extraction is to elution the red yeast rice with sodium hydroxide solution,then add the sodium sulfite to sulfonate the monascus red pigment,so we can obtain the water-soluble monascus yellow pigment.When we use the method to convert the alcohol-soluble monascus pigment into water-soluble monascus yellow pigment,the optimal conditions are the concentration of NaOH solution of 0.15 mol/L,the solid-liquid ratio of 1:15,extraction temperature of 80?,sulfonation reaction temperature of 70?,and the color value of the water-soluble monascus yellow pigment we obtain is 2125u/g.Compare the above two methods.of preparing water-soluble Monascus yellow pigment,and we arrive at a conclusion:although the color value of the water-soluble monascus yellow pigment we obtain by the method of sodium hydroxide eluent-sulfite sulfonation,is lower than the color value of the water-soluble monascus yellow pigment we obtain by the method of ethanol extract-sulfuric acid sulfonation by 28.7%,taking into account the factors of the simplification of the production process,the costs of investment,operation and maintenance in production equipment,safety,environmental protection and so on,alkaline extraction is better than ethanol extraction.So preparing water-soluble Monascus yellow pigment by alkaline extraction is the better method,and this method is worth popularizing.But the method of preparing water-soluble Monascus yellow pigment by alkaline extraction still has some shortcomings,so we need to further improve the conditions to improve the color value of the water-soluble monascus yellow pigment we obtain by conversion.