红曲液态发酵高产色素低产桔霉素的工艺条件

通过优化液态发酵过程及提取精制过程中的相应措施,可有效降低红曲桔霉素含量。优化后的小型发酵罐主要工艺条件是:精选氮源(大豆水解液为佳);合理的通风量和搅拌转速小型罐通风强度1.0L/(L·min),转速200r/min];在较高的温度下发酵(36℃);尽可能缩短发酵时间(96h);成熟发酵液在过滤前调节pH,使色素沉淀,从而与桔霉素分离。所得到红曲红色价分别为2 000U/g、10 000 U/g,桔霉素含量分别为0.282 mg/kg和1.373 mg/kg(折算为500U/g时的桔霉素含量为0.075mg/kg和0.067mg/kg),均低于红曲色素日本标准中桔霉素含量的限量指标(0.2 mg/kg即500 U/g)。说明通过发酵工艺及提取精制的优化,在不影响色素高产的情况下可将红曲色素中的桔霉素含量降至理想的水平。

The Study on the Fermentation Control of High Pigment Production with Low Citrinin Concentration

By controlling fermentation,recovery and refining conditions,it is possible to reduce citrinin content in Monascus products.The fermentation and recovery conditions were as follows:hydrolysate of soy- bean is used as nitrogen source in fermentation media.Suitable aeration and agitation speed(aeration intensi- ty is 1.0L/(L·min)and the agitation speed is 200r/min for a 15 L fermenter).Fermentation temperature is higher than usual(36℃); the fermentation time is relatively short(only 96 hours in one fermentation cycle). After fermentation the broth is acidified to precipitate the pigment.As a result the concentrationb of citrinin was 0.282mg/kg in the Monascus pigment at 2000 U/g and 1.337mg/kg in 10000 U/g.According to Japan National Standard issued by Japan Food Additives Association,the relative content of citrinin to Monascus pigments(citrinin 0.2mg/kg based on pigment at 500U/g)is 0.075mg/kg and 0.067mg/kg,respectively, which are lower than limitation raised by Food Additive Association of Japan.