Continuous production of ellagic acid in a packed-bed reactor

• Ellagitannase was auto-immobilized into polyurethane foam.
• Particles of polyurethane foam with ellagitannase activity were used as biocatalyst for continuous ellagic acid production.
• The ellagitannase packed-bed-reactor used showed good operational and mechanical stability.
• High volumetric yield of ellagic acid from pomegranate husks ellagitannins in a continuous process is described.

Ellagic acid is a high-value bioactive compound that is used in the food, cosmetic and pharmaceutical industries. The aim of this work was to develop a continuous system for ellagic acid production. Ellagitannase produced by solid-state fermentation and attached to polyurethane foam particles was used as a biocatalyst in a continuous bioreactor for the hydrolysis of ellagitannins from pomegranate by-product. A packed-bed reactor containing the biocatalyst (22.22 Units per gram of dry solid, U gds−1) was fed with a pomegranate ellagitannins solution (0.1%, w/v) at a flow rate of 0.27 mL min−1 at 60 °C. The bioreactor completed several biotransformations while maintaining the hydrolysis rate (60%) with a half-life of 10 continuous cycles of ellagic acid production. Volumetric productivity and ellagic acid yield were 1.09 g L−1 h−1 and 235.89 mg g−1 of pomegranate ellagitannins during the first 70 min of hydrolysis, respectively. The developed biocatalyst showed good operational and mechanical stability and may be successfully used for ellagitannin hydrolysis in a continuous system. This is the first report of high-yield continuous production of ellagic acid using an auto-immobilized enzyme.