Effective delignification of cabbage stem by organosolvent pre-treatment and subsequent enzymatic hydrolysis of pre-treated substrate

Non-edible portions of brassica vegetables are discarded in huge quantities, which is a great concern for causing environmental pollution. In the present study, cabbage stem was utilised for fermentable sugars production through enzymatic hydrolysis. Proximate composition of cabbage stem showed presence of lignocellulosic components (cellulose, hemicellulose and lignin) in appreciable amounts. Different pre-treatment approaches (acid, alkali and organosolvent) have been investigated for the effective delignification of cabbage stem and subsequent enzymatic hydrolysis of pre-treated substrate for better release of fermentable sugars. Organosolvent pre-treatment released highest quantity of cellulose content (69.28 ± 0.58a%) in comparison to acid and alkali pre-treatment. Optimisation of different process conditions for enzymatic saccharification of pre-treated cabbage stem with cellulase enzyme was carried out and maximum yield of reducing sugar content of 782 ± 1.14b mg/g was achieved at 1.5% (w/v) substrate concentration, 50°C temperature, pH 4, usage of 15 U/g enzyme concentration, and incubation time of 240 minutes. Valorisation of cabbage stem as the novel lignocellulosic waste sources into bio-products through enzymatic saccharification process for the mitigation of environmental pollution caused by the accumulation of these household or domestic organic residues has an added advantage.