Statistical investigation of the bioprocess conditions of alkali combined twin‐screw extrusion pretreatment to enhance fractionation and enzymatic hydrolysis of bulgur bran

Abstract

BACKGROUND Bulgur bran (BB) is a potential source for the production of value‐added products such as fermentable sugars and xylooligosaccharides (XOs). In this study, alkali combined twin‐screw extrusion pretreatment was performed and statistically optimized to enhance fractionation and enzymatic hydrolysis of BB. The pretreatment conditions (barrel temperature, screw speed and alkali impregnation) were optimized by Box–Behnken design (BBD) to obtain the highest hemicellulose separation from BB. The obtained fractions were analyzed for the production of fermentable sugars and XOs. RESULTS The results revealed that twin‐screw extrusion of BB performed at 67 °C barrel temperature and 250 rpm screw speed after alkali impregnation at 0.02 g alkali g−1 biomass concentration provided 40.4% higher hemicellulose separation yield compared to the untreated BB. Alkali combined twin‐screw extrusion pretreatment increased the enzymatic hydrolysis yield of BB fourfold, whereas a 13‐fold increase was achieved after the separation of hemicellulose from pretreated BB. Xylose (X1)‐free xylobiose (X2) was the main product after xylanase hydrolysis of hemicellulose fraction. SEM images confirmed the morphological modifications in BB, which were in agreement with the enhanced fractionation performance and the higher enzymatic hydrolysis yield. CONCLUSION The results of this study suggested that pretreatment by alkali combined twin‐screw extrusion followed by alkali extraction could be a reliable and effective process for fractionation of BB and production of fermentable sugars and XOs. © 2022 Society of Chemical Industry.

A mini review of electrocatalytic upgrading of carbohydrate biomass—System, path, and optimization

“…Despite these drawbacks, the alkali-catalyzed hydrolysis method presents milder conditions and higher product selectivity and deserved for more research in future development. 128,129 Unlike the electrocatalytic oxidation of HMF, there are few studies on the electrocatalytic conversion of glucose-based carbohydrates, and most of the research on glucose is focused on the detection of glucose in the blood and the application in the direction of fuel cells. [130][131][132][133][134] Until recently, researchers have been gradually focusing on the electrocatalytic oxidation of glucose to obtain high-value-added chemical products.…”

“…However, slower reaction speed, requirement for more alkali, and complicated sodium removal treatment limit its industrial application at present. Despite these drawbacks, the alkali‐catalyzed hydrolysis method presents milder conditions and higher product selectivity and deserved for more research in future development 128,129 …”