Conference Abstract Book

RECOMBINANT CHYMOSIN EFFECTIVELY ACTS ON MILK COAGULATION AFTER IMMOBILIZATION ON CHITOSAN-BASED NANOPARTICLES M. Patila 1 , C. Alatzoglou 1 , , A. Skonta 1 , M. Bellou 1 , S.Spyrou 1 , M. Papachristou 1 , P. Kyriakou 1 , A.C., Polydera 1 ,D. Houhoula 2 , H. Stamatis 1,* 1 Laboratory of Biotechnology, Department of Biological Applications and Technologies, University of Ioannina, Ioannina, Greece ( * hstamati@uoi.gr) 2 Department of Food Science and Technology, University of West Attica, 12243 Athens, Greece Chymosin (EC 3.4.24.3) is the preferred proteolytic enzyme used in cheese production. Compared to its soluble form, immobilized chymosin offers several advantages for the enzymatic coagulation of milk and has potential applications in cheese manufacture. Immobilization enables enzyme reuse and can affect chymosin’s interaction with milk proteins and the casein micelle structure. To improve the availability of chymosin in cheese production, recombinant bacterial chymosin was covalently immobilized on chitosan nanoparticles and evaluated. The catalytic activity—measured by the ability of chymosin to coagulate skim milk proteins—was preserved after immobilization. However, the immobilization method significantly influenced the enzyme’s catalytic performance. The immobilized chymosin exhibited stability for up to 15 days at 30 °C and retained activity for at least eight reuse cycles. Furthermore, its storage, thermal, and operational stability were up to five times higher than those of the free (non-immobilized) enzyme. Acknowledgements : We acknowledge support of this work by the project «Effect of Lactobacillus bacteria in highlighting special characteristics of traditional Greek cheeses (ΥΠ3ΤΑ-0559624) ), which is implemented under the action SYB1.1 Clusters of Research Excellence (CREs- 5180519)), Greece 2.0—National Recovery and Resilience Fund and funded by the European Union NextGenerationEU