Role of energy irradiation in aiding pretreatment of lignocellulosic biomass for improving reducing sugar recovery

With the depletion of crude oil reserves, the ever-increasing global energy consumption encourages the efforts to find alternative renewable sources for production of biofuels and value-added chemicals. The conversions of lignocellulosic biomass into biofuels and commodity chemicals via the biotechnological pathway have been the recent trend. Specifically, these products can be obtained through fermentation of reducing sugars, which are the main but basic derivatives from the biomass. In order to overcome the recalcitrant structure of the biomass for effective reducing sugar recovery, a pretreatment stage is normally required. Currently, one of the most novel forms of biomass pretreatment is using energy irradiation methods such as electron beam, gamma ray, pulsed electrical field, microwave and ultrasound. In general, these technologies are often used together with other more conventional chemical and/or biological pretreatment techniques for enhancing sugar recovery. Nevertheless, energy irradiation offers significant improvement in terms of possible cost reduction opportunities and reduced toxicity. Hence, this review highlights the recent studies of using energy irradiation for pretreating biomass as well as the industrial applications of reducing sugars in biotechnological, chemical and fuel sectors. In short, more research needs to be done at the scientific, engineering and economic levels to make energy irradiation one of the front runners in the field of biomass pretreatment.