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β-Agarase immobilized on tannic acid-modified Fe3O4 nanoparticles for efficient preparation of bioactive neoagaro-oligosaccharide

Xiao, Qiong, Liu, Chunli, Ni, Hui, Zhu, Yanbing, Jiang, Zedong, Xiao, Anfeng
Food chemistry 2019 v.272 pp. 586-595
Fourier transform infrared spectroscopy, antioxidants, beta-agarase, coprecipitation, iron oxides, magnetism, nanoparticles, pH, tannins, temperature, thermal stability, thermogravimetry, transmission electron microscopy
β-Agarase was immobilized by using tannic acid modified-Fe3O4 magnetic nanoparticles (TA-MNPs) as a supportmaterial. The MNPs were synthesized by improved chemical coprecipitation method and modified with TA for agarase immobilization. TA-MNPs and immobilized β-agarase were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA), all of which indicated the successful surface modification of MNPs with TA and the immobilization of β-agarase. The optimal immobilization conditions for 25 mg TA-MNPs included 100 r/min oscillation speed, immobilization time of 2 h, immobilization temperature of 15 °C, and initial β-agarase concentration of 3 mL (480 U). Immobilized β-agarase showed better pH and thermal stability and excellent reusability than the free enzyme. Results revealed the promising application of β-agarase-TA-MNPs for the preparation of neoagaro-oligosaccharides with different averagepolymerizationdegrees and varying activities in the antioxidant.