Development of a biocomposite based on alginate/gelatin crosslinked with genipin for ß-galactosidase immobilization: Performance and characteristics.

In this work, we studied the development of a biocomposite formulated with alginate and gelatin, crosslinked with genipin for application as support for ß-galactosidase immobilization. Also, the biocomposites with the immobilized enzyme were characterized by thermal analyses and SAXS (size, density, and interconnectivity of alginate rods) for a detailed analysis of the microstructure, as well as the thermal and operational stabilities of the enzyme. The structural modifications of the biocomposite determined by SAXS demonstrate that the addition of both genipin and enzyme produced a significant reduction in size and density of the Ca(II)-alginate rods. Immobilized ß-galactosidase could be stored for 175 days under refrigeration maintaining 80% of its initial activity. Moreover, 90% of its relative activity was kept after 11 reuses in a batch process of lactose hydrolysis. Thus, the biocomposite proved to be effective as support for enzyme immobilization.

Highly stable novel silica/chitosan support for ß-galactosidase immobilization for application in dairy technology.

ß-d-Galactosidase is an important enzyme in the dairy industry, and the enzyme from the yeast Kluyveromyces lactis is most widely used. Here, we report immobilization of the enzyme on a silica/chitosan composite support, devised to have 10% and 20% chitosan (SiQT10 and SiQT20, respectively). Morphological and textural characterizations showed that chitosan is dispersed in micrometric regions in silica. For comparison, a silica organofunctionalized with 3-aminopropyltrimethoxysilane (SiO2aptms) was prepared. Performance of the biocatalysts was tested for lactose hydrolysis, and the enzyme immobilized in SiQT10 and SiQT20 composites showed higher efficiency (62% and 47%, respectively) compared with the enzyme in SiO2aptms. Operational stability in this system was evaluated for the first time. After 200 h of continuous use in a fixed-bed reactor, SiQT10 remained with approximately 90% activity. Thus, in addition to demonstrating compatibility for food processing, these results align the enzyme stabilization properties of chitosan with the mechanical resistance of silica.