Study On Utilization Of Waste Starch In Food Waste

With the increase of our country’s population and the improvement of people’s living standards, the output of food waste has increased greatly. It is estimated that China has an output of food waste no less than 60 million tons annually. On the one hand, if the food waste could not be appropriately handled, it will do great harm to our health. On the other hand, the reasonable recovery and utilization of food waste to prepare value-added products can bring huge economic and social benefits. In this study, the food waste from Fancheng canteen of Wuhan Institute of Technology was analyzed and its composition and physiochemical properties were determined. The resourceful use of the food waste was realized by employing three different approaches and the main research results are as follows:(1) Fermented organic fertilizer was prepared by using the solid food waste as raw material. The suitable moisture content of fermented material is between 55% and 60%, sorting and crushing of food waste is conducive to fermentation, and the appropriate temperature in the fermentation process(such as 40 degrees centigrade) can play a role in shortening the period of fermentation and increasing the degradation rate of organics. The degradation rates of starch, fat and protein were 72%, 23% and 35%, respectively. The organic fertilizer fermented by solid waste with a organicscontent of 97%, an organics yield of 57%(based on the mass of dry material), a(N+P2O5+K2O) content of 6.5% and a pH value of 5.6 can match the standard of NY 52-2012.(2) Oxalic acid was prepared by using starch in solid food waste. The optimum preparation parameters are as follows: 20 mL of sulfuric acid, 65 mL of nitric acid and 0.1 g of catalyst is used for 30 g of starch; the reaction temperatures of hydrolysis stage and oxidation stage are 90 ℃ and 65 ℃, respectively; thereaction times of hydrolysis stage and oxidation stage are 2h and5 h, respectively; and the appropriate time for adding nitric acid and sulfuric acid is 4 h. The oils and salts in the food waste has negligible effect on the yield and quality of oxalic acid and under the optimum conditions the yield of oxalic acid can reach a high level.(3) Ethanol was prepared by food waste fermentation.The hydrolysis rate of starch can reach 86.7% after 5 h of hydrolysis of food waste in 1% sulfuric acid. After hydrolysis, Ca(OH)2 is added to adjust the pH value of hydrolysate andCaSO4 precipitation is generated.Yeast has a good adaptability in high salt and high oil environment.The system from both acid hydrolysis andmicrowave sterilization in the first 20 h of fermentation produce large amounts of CO2, while CO2 produced by the latter is slightly lower than that by the former.Experimental results show that after 30 h of fermentation, the ethanol content of the latter in the fermentation broth is 25.6 g/kg, the former is 29.2 g/kg.Since the environmentally friendly microwave sterilization has the advantages of low power consumption and low cost, it has promising application in food waste fermentation.