Oil palm trunk biomass pretreatment with oxalic acid and its effect on enzymatic digestibility and fermentability

Biotechnological enhancement of lactic acid conversion from pretreated palm kernel cake hydrolysate by Actinobacillus succinogenes 130Z

“…Similarly, Bukhari and co-workers obtained higher yield of hemicellulose i.e. xylose (60.3%) while pretreating OPTB with 4% (w/v) oxalic acid at 121 °C for 100 min 28 . On a different note, about 8.91 g/L mannose was obtained from PKC pretreated using 1% (v/v) sulfuric acid 29 and 13.54 g/L mannose was obtained from acai seeds pretreated using 1.5% (w/v) sulfuric acid at 121 °C 30 ; both of which are comparable to the findings in this study.…”

“…This glucose yield was higher than that obtained from corncob pretreated at much higher concentration of oxalic acid (15%, w/v), i.e., 25.18% of fermentable sugars 32 . Conversely, pretreatment using 5%, w/v of citric acid and acetic acid only recover 12.9% and 20% of sugars, respectively 28 . Meanwhile, at lower oxalic acid concentrations (1–2%, w/v), the enzymatic digestibility was at lower rate of 64.7%.…”

“…Following that, pretreatment using oxalic acid was performed at different concentrations (1–5%, w/v) and reaction times (1–5 h) to find a suitable catalyst conditions in hydrolysing the PKC, aiming at recovering the highest possible amount of fermentable monomeric sugars in the form of mannose and glucose. Accordingly, oxalic acid affects the composition of PKC components by hydrolysing the hemicellulose component (releasing mostly mannose in the pretreated liquor) 28 . During the acid pretreatment, the sugar released was higher at higher oxalic acid concentrations under the severity factor of log R 0 = 0.684.…”

“…Moreover, acetic acid, an inhibitory compound, was accumulated at higher oxalic acid concentration (Table 1 ). The severity factor for the optimum oxalic acid hydrolysis used in this study was calculated according to the equation described by Bukhari et al 28 and was determined as 0.684, which is comparatively low. The released acetic acid concentration was 0.031 g/L when pretreated with 3% (w/v) oxalic acid.…”

“…It was reported that negligible amounts of formic acid, furfural and HMF were detected in oxalic acid-pretreated hyrolysate of PKC due to low severity employed (i.e. log R 0 < 1.0) 28 . The formations of formic acid, furfural and HMF were not detected in this study, which further proved the mild conditions established for oxalic acid pretreatment.…”