Optimization of Solid State Fermentation Conditions of Rabdosia rubescens Dregs
In order to select the optimum conditions for solid state fermentation of Rabdosia rubescens dregs,the effects of yeast and lactic acid bacteria solid state fermentation on the content of oleanolic acid,ursolic acid,crude protein,crude fiber,crude fat,calcium,crude ash and lysine were studied under different inoculation amount,different ratio of material to liquid,different fermentation time and different fermentation temperature,andcorrelation and principal component analysis was conducted.The results showed that the optimal fermentation conditions of solid state fermentation of yeast were as follows:inoculation amount was 6%,feed-liquid ratio was 1∶1.2,fermentation time was 3 days and the temperature for fermentation was 28℃.Under these conditions,the contents of crude protein,crude fat,calcium,crude ash,oleanolic acid and ursolic acid increased by 0.93%,23.08%,13.89%,19.74%,15.00%and 16.22%respectively.The content of crude fiber decreased by 1.19%compared with that before fermentation.The correlation between oleanolic acid and ursolic acid reached 0.86,showing an extremely significant positive correlation.The correlation between crude protein and calcium,crude ash and lysine reached 0.95,0.97 and 0.90 respectively,showing an extremely significant positive correlation.The optimal fermentation conditions for lactic acid bacteria were:inoculation amount was 6%,feed-liquid ratio was 1∶1.2,fermentation time was 6 days and the temperature for fermentation was 28℃.Under these conditions,the contents of crude protein,crude fat,calcium,crude ash and lysine increased by 33.02%,23.08%,74.07%,51.32%and 21.21%respectively,and the content of crude fiber decreased by 24.76%.The correlation between crude protein and lysine reached 0.77,showing a very significant positive correlation.In summary,both yeast and lactic acid bacteria solid fermentation can improve the nutritional value of Rabdosia rubescens dregs.
Rabdosia rubescens dregsSolid state fermentationFermentation processYeastLactic acid bacteria