VALORIZATION OF RICE HUSK FOR CITRIC ACID PRODUCTION USING ASPERGILLUS NIGER BY SOLID STATE FERMENTATION

VALORIZATION OF RICE HUSK FOR CITRIC ACID PRODUCTION USING ASPERGILLUS NIGER BY SOLID STATE FERMENTATION

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background of Study

The amount of wastes produced from agro-processing industries is continuously increasing and poses serious environmental problems. This reason leads to many research groups to be investigating the opportunities for the valorization of such residue (Tobias et. al., 2014).

Agricultural residue is any unwanted or unsalable material produced wholly from agricultural operations which is directly related to the growing of crops or raising of animals for the primary purpose of making a profit or for a livelihood (Tobias et. al., 2014). The term “agricultural residue” is used to describe all the organic materials which are produced as by-products from harvesting and processing of agricultural crops.

Agricultural residues, which are generated in the field at the time of harvest, are known as primary or field based residues whereas those that are co-produced during processing are called secondary or processing based residues (Zafar, 2013). Many agricultural residues such as apple pomace (Hang and Woodams, 1984), kiwifruit peel (Hang and Woodams, 1987), orange waste (Aravantinos-Zafiris et. al., 1994), sugar cane bagasse (Shankaranand and Lonsane, 1993), coffee husk (Shankaranand and Lonsane, 1994), carrot waste (Garg and Hang, 1995), pineapple waste (Tran et. al., 1998), cassava bagasse, (Vandenberghe et. al., 1999), pumpkin (Majumdar, et. al., 2010), date syrup (Mostafa and Alamri, 2012), rice straw (Ali et. al., 2012), and oat bran (Raja and Kruthi 2013) were tried successfully as substrates for citric acid formation and under optimum conditions are known to produce good quantities of citric acid.

Rice husk (or hull) is the outermost layer of the paddy grain that is separated from the rice grains during the milling process (Alaric 2013). Rice husk is one of the most widely available agricultural residues in many rice producing countries around the world (Ajay et al., 2012). It has potential application in different field of endeavour which includes; preparation of activated carbons, insulating board material, chopstick production, fuel in power plant, source of silica and silicon compound, etc. (Ajay et al., 2012).

VALORIZATION OF RICE HUSK FOR CITRIC ACID PRODUCTION USING ASPERGILLUS NIGER BY SOLID STATE FERMENTATION