Study On Stability Of Monascus Pigment And Development Of Color Stabilization

Monascus pigment is a kind of natural pigment which is widely used in food industry.In this study,effect of pH,light,and temperature on the stability of monasus pigment by submerged fermentation were investigated and the degradation characteristics of monascus pigment under light or thermal conditions were also studied.Monascus pigments mixed with four kinds of carriers and three kinds of antioxidants respectively are used to select the optimal color stabilization of monasua pigments by comparison of the stability effects.The results are as follows:Firstly,monascus pigment is the most stable in the range of pH5.75-9.05 and its structure is broken under strong alkali and acid conditions.Monascus pigment has poor photostability and thermal stability.Light degradation dynamic model of monasus red pigment-water solution was established.It was proved that it was in accordance with the second order reaction kinetics.The thermal degradation dynamic model of monasus red pigment-solution was in accordance with the first order reaction kinetics and the thermal degradation activation energy（E_a）of Monascus red pigment was 43.5kJ·mol^-1.Secondly,as carriers of monascus pigment,microcrystalline cellulose,β-cyclodextrin,sodium alginate and gelatin are used to test photostability and thermal stability.The results show that only monascus pigment with sodium alginate can significantly improve photostability and thermal stability.Three kinds of antioxidants including ascorbic acid,quercetin andβ-carotene are added to monascus pigment separately.These antioxidants enhance the monascus pigment photostability but they have no effect on improving thermal stability.Since quercetin can change the color of monascus pigment,only sodium alginate,ascorbic acid andβ-carotene are selected as the compositions of color stabilization.Finally,effects on photostability and thermal stability of monascus pigment by the combinations with different concentrations of sodium alginate,ascorbic acid andβ-carotene are compared.The final optimal combination is 1.5%（m/v）sodium alginate and 0.01μg/mLβ-carotene.