A serial membrane-based process for fractionation of xylooligosaccharides from sugarcane straw hydrolysate

Abstract

• Valorization of sugarcane straw biomass for XOS obtainment. • Proposal of a serial NF membrane-based process for XOS fractionation. • Evaluation of diafiltration operation mode for improvement. • System performance with 3.7 g/L, 20.9% purity, and 46.0% yield for LMW XOS. • Potential of integration with other downstream strategies for XOS production. Xylooligosaccharides (XOS) can be obtained from sugarcane straw hydrolyzed liquor (SSHL) after pre-treatment by deacetylation followed by hydrothermal process. The fractionation of low molecular weight XOS (LMW XOS) such as xylobiose (X2) and xylotriose (X3) from high molecular weight XOS (HMW XOS) such as xylotetraose (X4), xylopentaose (X5), and xylohexaose (X6) is a challenge to be overcome in SSHL for either biotechnological applications or functional foods applications with prebiotic potential. In this study, we proposed and investigated the nanofiltration (NF) membranes technology configured as a serial process for XOS fractionation from SSHL to isolate LMW XOS. In our findings, the first membrane selected was NP030 (polyethersulfone material with MWCO of 500–600 Da) and the second one was TS40 (polypiperazine material with MWCO of 200–300 Da). Then, the selected membranes were operationally optimized for pressure, temperature, and pH: target in NP030 was for increasing the HMW XOS rejection with its best conditions under 40 bar, 20 °C, and pH 4.6, while targets in TS40 were for increasing the LMW XOS rejection and decreasing the xylose (X1) rejection with its best conditions under 20 bar, 50 °C, and pH 4.6. Finally, the operation of diafiltration (DF) was investigated and it was found that 1-time DF in each membrane could improve the performance indices for LMW XOS in the serial membrane-based process, achieving final values of 3.7 g/L of concentration, 20.9% purity, and 46.0% yield. This study brought great contribution to XOS fractionation using NF membranes technology, mainly due to the protocol of investigating DF influence.