Two-step purification of epilactose produced by cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus

Epilactose is a functional sugar that can be produced from lactose using cellobiose 2-epimerase and it is considered a developing prebiotic. In that sense, the development of strategies to produce and purify epilactose is key for its wider use in the food industry. The aim of this work was to establish a food-grade purification strategy suitable to be scaled-up to an industrial level. Firstly, the epilactose was produced by enzymatic epimerization of lactose in a reaction catalyzed by the recombinant cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus produced by Saccharomyces cerevisiae. Then, to remove the unreacted lactose, a screening study was performed to find a suitable 8-galactosidase enzyme with high lactose hydrolysis capacity but low ability to convert the epi-lactose. The elimination of the generated monosaccharides was then attempted by microbial treatment using different microorganisms and using activated charcoal. The baker's yeast S. cerevisiae was proven to be the most suitable microorganism for glucose and galactose removal from the reaction mixture. Overall, an attractive and food-grade two-step process for epilactose recovery was established, resulting in a purity and yield of 87% and 76.4%, respectively. Additionally, the INFOGEST 2.0 static in vitro simulation of gastrointestinal food digestion was used, for the first time, to assess the resistance of epilactose (77% resistance) to the upper gastrointestinal tract conditions, reinforcing its potential to be used as prebiotic.

Automated summary

The aim of this study was to establish a food-grade purification strategy for the production and purification of Epilactose, a functional sugar. Epilactose was produced by enzymatic epimerization and unreacted lactose was removed using a suitable 8-galactosidase enzyme. Monosaccharides generated during the reaction were eliminated through microbial treatment or activated charcoal. The resulting two-step process achieved an 87% purity and 76.4% yield of Epilactose. Additionally, the resistance of Epilactose to gastrointestinal conditions was evaluated using in vitro simulation, demonstrating its potential as a prebiotic.