Integrated approach of surfactants and fed-batch saccharification of alkaline pretreated corn cob for the enhancement of 2G-ethanol production

This study aimed to improve the saccharification of alkaline pretreated corncob (CC) through the addition of surfactants and high solid loading via fed-batch mode, and investigate their effects in the second-generation (2G) ethanol production. The pretreatment with 1 % (w/v) sodium hydroxide (NaOH) for 1 h at 160 °C resulted in an elevated delignification rate (72 %), with preservation of the polysaccharide fraction. The conventional hydrolysis of both raw (RCC) and pretreated corncob (PTCC) was performed with 10 % solids (w/v) using 12.5 FPU of Cellic® CTec3 per gram of cellulose or biomass for 72 h. In addition, the influence of the surfactants Tween 20 and Tween 80 was evaluated at different percentages. The initial data showed that the use of 1 % Tween 20 and the enzymatic load per gram of biomass yielded the highest total reducing sugar (TRS) release (69.71 g/L). The fed-batch saccharification carried out with gradual additions of PTCC up to reach 35 % of solid load (w/v) achieved elevated TRS concentration (164.52 g/L) after 72 h. The 1 % Tween 20 PTCC hydrolysates from the fed-batch saccharification were fermented with Saccharomyces cerevisiae for sugar-to-ethanol conversion, and produced a maximum of 28.78 g/L of ethanol, with a fermentative efficiency of 114 % in comparison to the fermentation of the hydrolysate without the surfactant. These findings highlight the beneficial potential of the combined strategy of alkaline pretreatment, fed-batch hydrolysis and 1 % Tween addition to maximize the feasibility of 2G ethanol.