Studiy On The Fermentation Of Monacus Pigment By Monacus And Stability Of Monacus Pigment

Monascus pigment, one of the secondary metabolites of Monascus belonging to polyketides, is a kind of natural edible pigments. In this paper, Monascus ZZ307was obtained by Monascus ZL307which was dealed with laser mutation treatment. The fermentation conditions for Monacus ZZ307to pruduce monacus pigment with bean dregs as raw material in liquid-state fermentation were studies. Response Surface Method was used to optimize the liquid-state fermentation mendium for monacus pigment production. The orthogonal experiment design was used to optimize the liquid-state fermentation condition. Uniform design was used to optimize the extraction condition of monacus pigment. Finally, the stability of monacus pigment under different condition was studied.Monascus ZL307was used as original strain by He-Ne laser mutation treatment. The results indicate that optimum conditions of the current intensity were:expanded beam spot diameter10cm, current intensity20mA, irradiation distance30cm, irradiation time50min. Mutant strain Monascus ZZ307was obtained, its incubation time of strains was shortened, maximum pigment color value increased by34%and the advance time of reaching the peak of color value was earlier compared to original strain. The heredity characteristics of the mutant strain were stable after subculture for generations.Based on the study of single factor tests, rice flour,(NH4)2SO4and MgSO4were found to be the most important factors to the color value of monascus pigment by Plackett-Burman experiment. Subsequently, the design of steepest ascent experimental was used to approach to the best concentration range of the three key factors. Box-Benhnken Design was used to optimize the fermentation medium components, and to confirm its experimental validity. The results showed that the optimal fermentation medium components were:bean dregs4%, rice flour3.4%,(NH4)2SO40.13%, CaCl20.25%, MgSO40.16%, K2HPO40.25%, distilled water100mL. In these conditions, monascus pigment color value was about23.4%higher than before.The levels of culture temperature, initial pH, rotate speed, volume, inoculability quantity etc were obtained by single factor tests. Selected of the initial pH, fluid volume and rotate speed three factors in orthogonal experiments. The obtained optimum culture conditions were:temperature 30℃, initial pH6, rotate speed180r/min, volume80mL, inoculability quantity5%. Under the above conditions, the total color value of monacus pigment reached125.84U/mL. In the batch fermentation process Monascus biomass, fermentation pH, color value of monascus pigment was investigated. And the result showed the color value of monacus pigment was partially growth-associated.The uniform design was adopted for getting the optimal technique parameters for extraction of monascus pigment by ultrasonic assisted ethanol technology. The results showed that the optimum extraction conditions were determined as follows:extraction temperature54℃, extraction time110min, ethanol concentration65%, Ultrasonic Power250w and extraction times was2. Under the above conditions, the color value of alcohol-soluble pigment was64.37U/mL, which was59.12%higher than before.The stability of Monascus pigment was affected by pH, metal ion, food additive, temperature and light value in some extent. The Monascus pigment had higher stability with pH5-9. The lower temperture had less influence on the stability of Monascus pigment. However with the heating time extending, the color value of the pigment would gradually decrease. After70min treatment under85℃,100℃,and121℃, the water-soluble pigment retention rate were94.02%,89.92%,84.74%, and the alcohol-soluble pigment retention rate were81.07%,75.03%,58.34%. Sunlight caused the most serious photodegradation for Monascus pigment, the indoor natural light was little comparatively, and has no effect under the dark condition (Olux). The preserving rate of Monascus pigment was decreased with increase of illumination intensity and irradiation time. Under the condition of same illumination intensity but different wavelengths, the successive order of preserving rate was red light, yellow light, green light, blue light and purple light. Monascus pigment was more sensitive to uvc light. Under the same condition, water-soluble pigment was more stable than alcohol-soluble pigments. Finally, used orthogonal design experiments to optimize the ratio of food additive (Vc, Sodium Citrate and EDTA-2Na), the pigment preservation rate was more than20%higher than the control group.