Galactonate bio-preparation from cheese whey waste and its application as a novel bio-retarder

Abstract

Cheese whey, as the major byproduct in cheese making, contains significant amounts of lactose, which can be efficiently hydrolyzed to glucose and galactose. Therefore, it is a potential resource for producing gluconic acid (GA) and galactonic acid (GalA) by Gluconobacter oxydans (G. oxydans). The glucose can be preferentially and rapidly bio-oxidized into GA by G. oxydans, however, the preserved GA and galactose would be simultaneously metabolized, meaning that the GA and GalA cannot be co-produced. Therefore, based on the kinetics of biphasic trend for glucose and galactose metabolism, a novel approach involving the integration of bio-oxidation and electrodialysis techniques was developed to sequentially convert glucose and galactose into GA and GalA, correspondingly. As a result, 79.2 g/L GA and 75.1 g/L GalA could be co-produced step by step from the enzymatic hydrolysate that contain approximately 80 g/L glucose and 80 g/L galactose. Furthermore, in this study, the evaluation experiment of GalA as cement additive suggested that it could be used as a novel bio-retarder with an excellent retarding effect, providing a new idea for cheese whey waste utilization.