Enzymes Production From Food Waste and Their Application

Introduction

According to a study by the Food and Agricultural Organisation (FAO), nearly 1.3 billion tons of foods produced globally are lost along the food supply chain. Food waste (FW) can be defined as a biodegradable organic waste discharged from different sources including food processing industries, households and hospitality sectors (FAO, 2012). The rise in population of the world is the main reason behind the increasing amount of FW which poses serious threat to the environment in the form of pollution, health risks and scarcity of dumping land. Among the well-developed nations, the United State, the United Kingdom and Japan are placed on top of the food waste list globally (Melikoglu et al. 2013a). About 96 billion pounds of food was wasted in the US and it amounts to 27% of the total food available for human consumption.

Food waste has been categorized depending on various factors based on the type of food as cereals, fruits, meat, fish, drinks, its nutrient composition as carbohydrates and fat based FW (Russ and Meyer-Pittroff 2004), chemical composition depending on its C, H, N, O, S and Cl content (Bernstad and La Cour Jansen 2012), storage temperature into ambient, chilled or frozen (Bernstad and La Cour Jansen 2012), household level waste as cooked and uncooked, unpackaged and packaged food waste. Food waste was classified into organic comprising fruits and vegetables, catering waste, animal by-products, packaging, mixed food waste and domestic waste by Lin et al. 2013.

In a study that reviewed the characteristics of treated food waste, loss of carbon, nutrients and other compounds during treatment, energy recovery through incineration, hazardous emission from composting, storage and use of bio-fertilizers and chemical fertilizers were found to be a direct cause that leads to global warming and other major environmental and health hazards. One of the main characteristics of food waste, that many other wastes lack is that food waste can be subjected to biological processes like before its disposal. But these processes can result in toxic emission that has negative impact on the environment and will affect its property for the recovery of nutrients and energy recovery by different alternative treatment techniques (Bernstad and La Cour Jansen 2012).

Inappropriate disposal techniques may lead to problems to both human and animal health and also incur serious economic, environmental and biological losses. Figure 1 depicts the propects and consequences of various food waste disposal methods. Composting and vermi-composting are better methods than incineration. The disadvantage of composting is that it is a slow process and requires large space and produces foul odors (Sharholy et al. 2008). Disposing at landfill sites is another more commonly employed system of waste disposal. But land filling poses the most serious environmental impacts compared to the other treatment options such as anaerobic digestion or composting and therefore should only be thought of as a last aid (Sharholy et al. 2008). Land filling can be employed for wastes that are not suited for recycling or biological processing which are non-biodegradable or inert. Under such circumstances where the safe and hygienic removal of food waste has become a serious issue, a best option is to utilize FW for its significant potential in the production of value-added products like enzymes, fuel, and various other products. Figure 3 gives an outline of the production of value-added products from food wastes. This paper reviews about the production of industrially important enzymes using FW as substrates. This method is not only important in an eco-friendly point of view but also economically valued.