Ammonium Gluconate Production from Potato Starch Wastewater Using a Multi-Enzyme Process

Abstract

In China, potato starch wastewater causes serious environmental pollution. Therefore, in this study, we aimed to develop a method for the transformation of potato starch in potato starch wastewater into ammonium gluconate, where potato starch wastewater was enzymatically hydrolyzed by liquefaction and saccharification. The optimum parameters of the hydrolysis process were as follows: α-amylase concentration, 0.5% (v/v); reaction time, 35 min; temperature, 90 °C; glucoamylase concentration, 0.7% (v/v); reaction time, 25 h; temperature, 50 °C; and pH, 4.0. Subsequently, ammonium gluconate was produced using 4.6 U/g glucose oxidase and 75 U/g catalase at 50 °C. The pH of the solution was maintained in the range of 6.8 ± 0.2. In the final crude ammonium gluconate-containing liquid, the protein, total nitrogen, total carbon, organic carbon, and ammonium salt content was 3.5 g/L, 8.47 g/L, 53.62 g/L, 13.79 g/ L, and 60 g/L, respectively. The environmental pollution was solved by using potato starch to produce value-added products.