Production of Bioenergy and Bioproducts from Food Processing Wastes: A Review

Abstract

Wastes from different food processing sectors are reviewed in terms of their availability, quality, and current utilizations. Technologies for value-added processing of different food wastes into bioenergy and biochemical products are briefly discussed. Part of food wastes is currently processed as animal feeds and organic fertilizers. Large amounts of solid food wastes are buried in landfills, while liquid food wastes are released into public sewer systems. High transport and landfill costs and strict governmental regulations have led to alternative utilization of food processing wastes. The selection of an appropriate process to recover materials and energy from food wastes largely depends on the characteristics of the waste, the desired forms of bioenergy and bioproducts, and the economical feasibility. Food processing wastes from fruits, vegetables, and grains contain large amounts of primary metabolites of lipids, proteins, and carbohydrates and a broad range of high-value bioactive compounds of phenolics, terpenoids, and alkaloids. Extraction techniques have been widely investigated to obtain valuable natural compounds from plant-based processing wastes. Wet plant-based food processing wastes, which are rich in sugars, vitamins, and minerals, have been used to produce fuel alcohols, organic acids, biodegradable polymers, enzymes, antioxidants, and vitamins in biological processes. Wet food processing wastes such as slaughterhouse wastes, fruit and vegetable processing wastes, and food processing wastewater are suitable for the production of biogas and hydrogen through anaerobic digestion. Non-edible oil cakes, which are rich in protein, have been used to adjust the carbon to nitrogen ratio of feedstocks in anaerobic digestion. Dry food processing wastes, such as rice husk, sugarcane bagasse, and oilseed cakes, can be used to supply heat and power in food processing facilities through combustion and produce gaseous fuels through gasification and liquid bio-oil through pyrolysis. Meat processing wastes have high contents of protein and fat. Animal fats and grease are potential feedstocks for biodiesel production.