Economic Utilization of Crop Residues for Value Addition: A Futuristic Approach

Abstract

The agricultural products (cellulosic and ligno-cellulosic, including soft- and hard-wood) having being produced by the photosynthetic processes, are virtually inexhaustible, and could be converted into highly attractive substrate for bioconversion processes. The structure of ligno-cellulosic material is based on three main components: cellulose, hemicellulose and lignin. These three components offer tremendous biotechnological potential to be used as substrate in bioconversion processes and can be effectively exploited for the production of bulk chemicals and value-added products. It is pointed out there is an urgent need to develop processes for economic utilization of these residues through the advances in biotechnology. Some major products which could be produced from these sources include ethanol, enzymes (e.g. cellulases (endoglu canases, exo-cellobiohydrolase and β-glucosidase), ligninases (laccase, Mn-peroxidase and Li-peroxidase), xylanase, pectinase, amylases, α- and β-galac tosidases , caffeinase, tannase), food and feed (probiotcis), etc. Some major residues which need special emphasis include sugar cane bagasse, cassava bagasse and coffee pulp. It is mentioned that additional research on the pre-treatment of feedstock is required to improve the components yield and the cellulose digestibility to the level, which would make usage of such residues economically viable. Similarly, although much efforts have been made in the past on the cellulose hydrolysis, its effective conversion into fermentable sugars is an area which needs further inputs in terms of R&D. It is argued that much need be done on the hydrolysis of hemicellulose (and soft-wood). An in-depth analysis is presented on the scenario of applications of crops residues in developing countries, particularly in India, with special reference to sugar cane bagasse, cassava bagasse and coffee pulp.