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Food Waste as a Global Concern
The global population is expanding at an exponential rate every year. There is a huge demand for food and energy to meet the needs of society. Rapid urbanisation combined with slow progress in the development of and ineffective waste management strategies leads to the accumulation of food waste. A study published by the EU in 2010 revealed that almost 90 million tonnes of food waste are expelled from the food manufacturing industry every year [1] . Food waste, being high in nutritional content, putrefies on accumulation, providing breeding grounds for disease-causing organisms. This poses serious environmental issues and very few options exist today to deal with them. While preventive measures can be taken to reduce the generation of food waste it is important to deal with the existing accumulated food waste. The idea of converting food waste into energy and other chemicals used in our daily activities is an area of research with huge potential and opportunities. This review deals with the types of food waste and problems associated with them, the legislation pertaining to reducing food waste as well as using it as a renewable feedstock (see Glossary ), and the various products and the latest valorisation techniques developed in recent years using food waste as a raw material.
Food Industry Waste as a Renewable Resource
Food industry waste is particularly interesting for renewable energy researchers as it is mostly lignocellulosic in nature, with high cellulose and lignin content (except animal-derived food waste). Many studies have reported on various technologies for the conversion of food waste such as apple pomace and brewers' spent grain into biofuel [2,3] . Cellulose and hemicelluloses on enzymatic breakdown release glucose and xylose, which can be converted into ethanol by fermentative microorganisms [4] . Furthermore, lignin on pyrolysis and anaerobic digestion yields H2 and CH4[5] . In the quest for renewable energy resources with the backdrop of rising oil prices, one overlooks the fact that food waste is a reservoir of other value-added chemicals. Recent studies suggest that the production of bulk chemicals from biomass waste is 3.5 times more profitable than converting it into biofuel [6] . Meanwhile, biorefinery is an emerging concept in the field of biomass waste management...