Bioconversion of beverage waste to high fructose syrup as a value-added product

Abstract

Waste valorisation practices have attracted a significant amount of attention in recent years with the aim at managing waste in the most sustainable way. Most of the studies focused on converting solid waste feedstock for value-added chemicals and fuels production. However, less effort has been devoted on liquid waste such as beverage waste which is a significant sewage stream in urban area. In this study, a bioconversion process was developed to produce low-cost fructose syrup using beverages waste as feedstock. The process composed of enzymatic hydrolysis, activated carbon treatment, ion exchange chromatography and ligand exchange chromatography. Beverages waste collected from local supermarket was treated by commercial pectinase and sucrase. Optimisation study on enzyme activities indicated that both enzymes were most active at 50°C and pH of 4.0–4.5. Hydrolysate containing 36.0g/L glucose and 45.0g/L fructose was then de-colourised in the activated carbon treatment. Also, more than 98% ions were removed after the cation and anion exchange chromatography. Lastly, high fructose syrup was produced by ligand exchange chromatography at a fructose separation efficiency of 74.9%. A total of 47.5% sugars in the hydrolysate were recovered as high fructose syrup, while the remaining sugars were in the glucose-rich stream. The proposed method would be a green and sustainable process for nutrient recovery in beverage waste valorisation. Future study should focus on increasing fructose separation efficiency by using simulated moving bed system and the enhancement of fructose production yield by isomerisation of glucose-rich stream.