Cross-linked levansucrase aggregates for fructooligosaccharide synthesis in fruit juices

Abstract In the present study, the cross-linked enzyme aggregates (CLEAs) of Y246S variant levansucrase from Bacillus licheniformis RN-01, known as oligosaccharide-producing levansucrase (OPL) was prepared for application in levan-type fructooligosaccharide (LFOS) synthesis in sucrose and fruit juices. The OPL-CLEAs with the highest immobilization yield (74.8% ± 8.9%) were prepared using 40 g/100 mL ammonium sulfate, 15 U/mL OPL, and 2 mg/mL bovine serum albumin in a 4 h cross-linking reaction. Compared with those of the free enzyme, the obtained OPL-CLEAs had a broader pH range for catalysis (pH 3–12) and displayed a higher optimum temperature. Moreover, the stability of OPL was significantly improved after immobilization, indicated by an increase in melting temperature and operational duration. Product analysis showed that the OPL-CLEAs could synthesize a similar LFOS profile as free enzymes, with a yield of up to 51%. Additionally, OPL-CLEAs could retain more than 50% of the initial activity after six cycles of reuse. Finally, the potential application of OPL-CLEAs in fruit juices was demonstrated by transforming up to 65%–75% of total sucrose in moderately acidic fruit juices. This study suggests the high potential for application of OPL-CLEAs in food industries.