The Study Of Monascus Yellow Pigment Influencing Factors On Monascus Solid-state Fermentation

Monascus red pigment has been widely used in a lot of food,yellow pigment,which is of extensive application prospect,had no enough research.However,citrinin,a human toxic substance,was also synthesized in this fungus.So how to improve the yield of Monascus yellow pigment and reduce the yield of citrinin is our research focus.The culture for fermentation is FJ3,which was determined by single-factor experiment.The conditions of this culture age were controlled 10%inoculation,35%initial water content,65%humidity and incubated at 30℃ for 6 days.In this condition,the yield of yellow pigment was 764±22 U/g,yellow tone was 0.97 and citrinin was 0.0465±0.0016 mg/g.We used single-factor experiments to screen the optimal single factors of solid-state fermentation of yellow pigment.The results showed that the optimal pH of water for soak was 4.5 adjusted by lactic acid in 4 diffident acid and in this condition,the yield of yellow pigment was 1427±86 U/g,yellow tone was 1.05 and citrinin was 0.0263±0.0024 mg/g;the optimal adding amount of rice husk was 8%for increasing the porosity of the medium and in this condition,the yield of yellow pigment was 2133±221 U/g,yellow tone was 1.06 and citrinin was 0.0131±0.0020 mg/g;the optimal physiological acid ammonium was 1.2 g/Kg ammonium phosphate and in this condition,the yield of yellow pigment was 2005±113 U/g,yellow tone was 1.14 and citrinin was 0.0472±0.0009 mg/g.Plackett-Burman design was applied to identify the significant factor.Among the eight metal ions,Na⁺、Fe²⁺、Cu²⁺ and Mn²⁺ influencing yellow pigment production were identified.A Box-Behnken design was further employed to investigate the optimum level of these.The maximum production of yellow pigment of 1828±156 U/g were achieved at the medium containing Na⁺2.0 mM/Kg,Fe²⁺1.0 mM/Kg and Mn²⁺2.0 mM/Kg and yellow tone was 1.23 and citrinin was 0.013610.0009 mg/g.An orthogonal experimental design was employed to investigate the optimum level of four Anti-oxidant.The maximum production of yellow pigment of 2988±85 U/g were achieved in the medium containing Vitamin C 16.0 g/Kg,L-cysteine 6.0 g/Kg,Calcium phyticl.4g/Kg and Calcium lactate 8.0 g/Kg and yellow tone was 1.39 and citrinin was 0.01766±0.0012 mg/g.According to the above experiment,Plackett-Burman design was applied to identify the significant factors for Yellow pigment.Among the seven factors which could significantly improve the yield of Yellow pigment,L-cysteine、Cu²⁺ and Rice husk influencing yellow pigment production were identified.A Box-Behnken design was further employed to investigate the optimum level of these.The maximum production of yellow pigment of 4008±49 U/g were achieved in the medium containing 5.0 g/Kg L-cysteine,2.25 mM/Kg Cu²⁺and 5%Rice husk and yellow tone was 1.16 and Citrinin was 0.0062 ±0.0005 mg/g.Yellow pigment increasing by 5.25 times,yellow tone increasing by 1.20 times and citrinin reduced 86.67%comparison with optimization.