Determination of Factors Affecting the Enzymatic Hydrolysis of Low Severity Acid‐steam Pretreated Agro‐residue

Abstract

AbstractAgro‐residues and their hydrolyzates are precursors for synthesis of biofuels and mesoporous carbons. However, factors like pH, biomass loading, temperature, and enzyme affect the recovery of carbon sugars, and limit the hydrolysis. This study determined the main factors affecting the hydrolysis by Principal Component Analysis (PCA). Corn cob was added to 1.2% hydrochloric acid and subjected to steam at 121 °C, 20 min (low‐severity, Step 1) following enzymatic hydrolysis (Step 2). Factor levels i.e., pH (4.5‐7.5), temperature (37, 45, 55 °C), biomass loading (50, 100, 200 g/L) and enzyme type (Viscozyme L and Cellulase, Sigma) were adjusted in Step 2. PCA of standardized measured variables (glucose, xylose, arabinose, reducing sugars (RS) and hydroxymethylfurfural (HMF) concentrations; and yields of glucose, xylose and RS) at various factor levels was performed. Principal component 1 and 2 could explain ca. 96% of the data variance (Fig. 1). Low biomass loading correlated with high yields of glucose, xylose and RS, whereas pH 5.5, 45 °C and cellulase correlated with high concentrations of glucose, xylose and RS. PCA can be an effective tool in the design of efficient hydrolysis method and evaluation of factors affecting pretreatment method.