Reasons for processing of rice coproducts: Reality and expectations

The increasing interest in reusing coproducts from rice crops, such as straw, husks, and bran, has motivated the writing of this review. The aim is to provide a critical and constructive overview of the main advantages and technological challenges for further processing such coproducts within the biorefinery concept. Current studies and applications are presented and discussed, which mainly include the use of such coproducts on energy and biofuel generations, production of building blocks, adsorption of recalcitrant substances, animal feeding and fertilization crops, extraction of bioactive compounds, and production of carbon-based and silica-based materials. Furthermore, the reality and expectations on processing steps (chemical, biochemical, and thermochemical routes), conventional and novel technologies and value-added products/derivatives with interest in several industrial fields are highlighted. As expectations, some companies and government projects are innovating and trying to use sub/supercritical water hydrolysis as a promising technology with high potential to decompose rice lignocellulosic biomass into small-chain sugars and bioproducts. Overall, as a future outlook for making most of the processing routes of rice coproducts more feasible, more infrastructure and scientific researches are needed to overcome some barriers and drawbacks that still exist in the subject presented in this review.