The green novel approach in hydrolysis of pistachio shell into xylose by microwave‐assisted high‐pressure CO2/H2O

Abstract

AbstractBACKGROUNDPistachio shell is a valuable lignocellulosic biomass because almost 90% of its hemicellulose fraction is xylan, which can be converted into high value‐added compounds such as xylooligosaccarides, xylose, xylitol and furfural. The present study represents a green and novel approach to produce xylose from lignocellulosic biomass. Microwave‐assisted high‐pressure CO2/H2O hydrolysis (MW‐HPCO2) comprising a combination never previously used was performed to produce xylose from pistachio shell.RESULTSResponse surface methodology with a Box–Behnken design was implemented to optimize microwave‐assisted high‐pressure CO2/H2O hydrolysis (MW‐HPCO2). The effect of temperature, time and liquid‐to‐solid ratio was studied in the ranges of 180–210 °C, 10–30 min and 5–30 mL g−1, respectively. A maximum xylose yield of 61.39% and minimum degradation compounds (5‐hydroxymethyl furfural and furfural) of 11.07% were attained under reaction conditions of 190 °C, 30 min and 18 mL g−1.CONCLUSIONThe results showed that hydrolysis temperature, time and liquid‐to‐solid ratio had a strong influence on the xylose yield, as well as on the formation of degradation compounds. MW‐HPCO2 significantly increased accessibility to cellulose‐derived products in the subsequent enzymatic hydrolysis. The results of the present study reveal that MW‐HPCO2 can be a promising green technique for the hydrolysis of lignocellulosic biomass. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.