Optimization of hydrothermal-assisted alkali process for enhanced xylan recovery from banana fiber biomass

Banana fiber is a rich lignocellulosic biomass source that has not been widely explored. The hemicellulose components (15 - 20 %) of banana fiber can be a feedstock for producing high-value commodity chemicals. Hemicellulose is extracted by physical, chemical, and biological methods, in which combining hydrothermal treatment with alkaline mode of extraction provides an enhanced recovery percentage. Thus, the present study aimed to optimize the hydrothermal-assisted alkaline method of xylan extraction from the banana fiber biomass. Initially, xylan was extracted with a conventional-based alkali method. A maximum of about 43 and 35 % was recovered from pretreated and raw banana fiber at 12% NaOH concentration when incubated at 55 °C for 24 h. To improve the xylan yield, the hydrothermal assisted alkali method experimented in which 67.1% and 58.3 % of xylan were recovered when treated at 121 °C for 1 h at 12% NaOH. To further enhance the xylan recovery, a two-step alkali process by combining conventional and hydrothermal-assisted alkali methods resulted in the highest xylan (81%) recovery from pretreated banana fiber when incubated with 12 % alkali for 8 h followed by steam treatment. On the other hand, a maximum of 73 % of xylan was recovered when steam treated after incubation for 24 h from raw banana fiber. Thus, the alkali incubation followed by steam treatment significantly showed the highest xylan recovery from the banana fiber biomass. The extracted xylan might be utilized as a source for various xylan-based products, including furfural, xylooligosaccharides, xylose, and xylitol, all of which have significant roles in the pharmaceutical and food industries.