Sequential optimization strategy for the immobilization of Erwinia sp. D12 cells and the production of isomaltulose with high stability and prebiotic potential.

Isomaltulose is a potential substitute for sucrose, with a high stability and prebiotic potential, for wide use in candies and soft drinks. This sugar is obtained from sucrose through enzymatic conversion using microbial glucosyltransferases. This work aimed to optimize a matrix to immobilize glucosyltransferase producing Erwinia sp. D12 cells using a sequential experimental strategy. The cell mass of Erwinia sp. D12 obtained in a bioreactor was immobilized in beads formed by ionic gelation. The conversion of sucrose into isomaltulose using the beads was performed in batch and continuous processes, and the isomaltulose was recovered through crystallization. The stability of isomaltulose was assessed in beverages of different pH values, and its prebiotic potential was verified with the growth of probiotic microorganisms. The optimized matrix composed of alginate (2.0% w/v), CaCl2 (2.0% w/v), gelatin (2.0% w/v), and transglutaminase (0.2% w/v) showed the highest mean of produced isomaltulose (199.82 g/L) after four batches. In addition, high stability during the continuous process resulted in an isomaltulose production above of 230 g/L for up to 72 h. The produced isomaltulose was more stable than sucrose in lemon soft drink and orange and grape energy drinks after 30 days of storage; and promoted the growth of Bifidobacterium animalis and Lactobacillus lactis. In conclusion, the production of isomaltulose by Erwinia sp. D12 cells immobilized using optimized conditions is recommended, due to its high conversion capacity, high stability, and prebiotic potential of crystals obtained.