Novel simplified biorefinery for puerarin separation and ethanol production from Puerariae lobatae Radix based on the process integration method

Abstract

Puerariae lobatae Radix (PLR) contains large amounts of puerarin and carbohydrates. It is a promising resource for puerarin and ethanol production. In this work, a novel simplified biorefinery was established to co-produce puerarin, ethanol and other high value chemicals from PLR based on the process integration method. Firstly, the acid hydrolysis of PLR was investigated and optimized. The acid hydrolysis of PLR realized the pretreatment of the PLR residue and the simultaneous hydrolysis of isoflavone (puerarin) derivatives and starch in PLR. Moreover, the acid hydrolysis of PLR enhanced the dissolution of isoflavone (puerarin) from PLR. Then, the simultaneous saccharification and co-fermentation of the PLR hydrolysate and PLR residue obtained from the acid hydrolysis were conducted to transform the carbohydrates in PLR into ethanol. Finally, the ethanol and puerarin were separated from fermentatin broth via fractional distillation, and the ethanol and puerarin were further purified. Under optimal conditions, 1 Kg PLR could produce 0.255 Kg anhydrous ethanol, 23.8 g puerarin with 92.9% purity, 11.6 g daidzein with 72.8% purity, 0.31 Kg calcium sulfate residue and 0.29 Kg fermentation residue. And 1 Kg PLR product value reached 5.75 USD at present price. This biorefinery streamlined its processes, fully utilized PLR components, and decreased waste generation. It could be a simple and efficient PLR deep processing technology.