Production of dietary fibers from sugarcane bagasse and sugarcane tops using microwave-assisted alkaline treatments

Sugar industries generate a big amount of residues during the harvest and milling of sugarcane. Both sugarcane bagasse and tops are two of the main biomass sources that potentially become part of the environmental pollution. These fibers can be theoretically used to obtain added value products, but require effective methods to separate lignin from biomass. The present paper intends to evaluate the effects of a microwave process (600 W, 5 min) applied during alkaline treatments of sugarcane bagasse (SBC) and sugarcane tops (SCTs) to separate lignocellulosic compounds and use them as nutraceutical ingredients of human food such as chapatti-type fermented bread and noodle-type pasta. Two alkaline treatments using sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) with concentrations of 15, 22.5, 30, 37.5 mmol were analyzed. The study found that the alkaline treatments assisted with microwave heating could remove lignin more efficiently than the traditional method (immersion). The assistance of the microwave process during alkaline treatments is an alternative to deconstruct the lignocellulosic structure. From the evaluated concentrations, the highest lignin removal was observed with NaOH (37.5 mmol) for both kinds of fibers. Hedonic responses suggest that the addition of 8 wt.% of treated fibers during the production of chapatti-type fermented bread (with SCB) or noodle-type pasta (with SCTs) is suitable for human consumption; additionally, dietary trends for lower digestibility were observed in the fortified food.