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Sequential acid hydrolysis and enzymatic saccharification of coconut coir for recovering reducing sugar: Process evaluation and optimization

Gundupalli, Marttin Paulraj, Bhattacharyya, Debraj
Bioresource technology reports 2019
Fourier transform infrared spectroscopy, X-ray diffraction, acid hydrolysis, beta-glucosidase, cellulose, coconuts, coir, crystal structure, endo-1,4-beta-glucanase, glucose, moieties, reducing sugars, saccharification, scanning electron microscopy, sulfuric acid, temperature
Sulphuric acid hydrolysis of coconut coir under case I (time: 2–10 min; temperature: 160–240 °C; acid concentration: 0.2–0.7% w/w) and case II (time: 10–60 min; temperature: 100–160 °C; acid concentration: 0.7–2% w/w) was studied. The optimal conditions for maximum recovery of reducing sugar for case I and case II were 8.2 min, 200 °C, and 0.21% w/w acid; and 13 min, 155 °C, and 1.27% w/w acid. Under these conditions, 52% and 48% of reducing sugar were recovered. Enzymatic saccharification was performed after hydrolysis using cellulase and β-glucosidase enzymes. Glucose yields of 90% and 55% were obtained in case I and case II, respectively. Changes in structure and functional groups in solid were observed when studied using SEM, XRD, and FTIR. The aromatic layer was removed in case I and cellulose layer was exposed. Crystallinity increased from 42 to 54% in case I and from 42 to 45% in case II.