Direct production of glucose from glycogen under microwave irradiation

Abstract

The production of fermentable sugars from renewable sources is a challenge. An attempt was made to exploit glycogen as a potential feedstock for the production of glucose. The microwave-assisted acidic hydrolysis was applied for glycogen decomposition for the first time. The optimal conditions for the hydrolysis reaction (yield of glucose -62 wt.%) were identified: microwave irradiation time -10 min and concentration of acid -1 M HCl. Microwave irradiation has dramatically reduced the reaction time from more than 6 h (at 80 uC under an oil bath) to 10 min. 13 C NMR spectroscopy was employed to monitor the progress of the hydrolysis reaction. HPLC analysis was employed to evaluate the yield of glucose. Thus, the viability of the use of glycogen as an economically and environmentally benign precursor to the production of glucose has been demonstrated.

Heteropoly acid catalyzed hydrolysis of glycogen to glucose

“…1). Moreover, peaks characteristic of glycogen (60.6 (C6), 69.4 (C4), 71.8 (C2), 73.4 (C3), 76.8 (C5), 99.6 (C1) ppm) were absent [17]. Thus the complete conversion of glycogen to exclusively glucose is revealed (Fig.…”

“…1). In addition, under the optimum reaction conditions, no by-products like HMF (177 (C1), 161 (C2), 152 (C3), 123 (C4), 110 (C5) and 57 (C6) ppm), levulinic acid (27.9 (C1), 29.1 (C2), 37.7 (C3), 177.4 (C4) and 213.7 (C5) ppm) and formic acid (166.3 ppm) were observed [17,19]. The details of the experimental studies that have led to the deduction of optimum reaction conditions for the hydrolysis of glycogen have been summarized in Table S1A.…”

“…S2a). Glucose formation is a result of the higher reaction temperatures obtained during MW irradiation [17]. As a further increase in the time of irradiation for achieving a complete conversion of glycogen is energy intensive, the option of increasing the catalyst amount was preferred.…”

“…With the aid of microwave (MW) irradiation and in the presence of mineral acid (HCl) catalyst glycogen was converted to glucose (62 wt. % yield) [17]. However, HCl is corrosive, and its separation needs further steps.…”

Isosaccharinic Acid Mediated Fine Chemicals Production from Cellulose

“…Slight up field shift in the δ values of the reaction product formic acid (8.5 ppm, Figure 2 (a)) relative to the authentic sample (7.5 ppm, Figure S1) is attributed to the alkali under atmospheric pressure in the presence of air. The output of the domestic microwave reactor was 900 W. The microwave oven was modified so as to have provision for a distillation column passing through the MW oven (for enhanced safety of operation) as well as a stirring facility during the reaction [21]. The cellulose decomposition reaction was carried out in a batch mode in a round bottom flask with provision for a reflux condenser.…”