Polymers as Encapsulating Agents and Delivery Vehicles of Enzymes.

Enzymes are versatile biomolecules with broad applications. Since they are biological molecules, they can be easily destabilized when placed in adverse environmental conditions, such as variations in temperature, pH, or ionic strength. In this sense, the use of protective structures, as polymeric capsules, has been an excellent approach to maintain the catalytic stability of enzymes during their application. Thus, in this review, we report the use of polymeric materials as enzyme encapsulation agents, recent technological developments related to this subject, and characterization methodologies and possible applications of the formed bioactive structures. Our search detected that the most explored methods for enzyme encapsulation are ionotropic gelation, spray drying, freeze-drying, nanoprecipitation, and electrospinning. α-chymotrypsin, lysozyme, and ß-galactosidase were the most used enzymes in encapsulations, with chitosan and sodium alginate being the main polymers. Furthermore, most studies reported high encapsulation efficiency, enzyme activity maintenance, and stability improvement at pH, temperature, and storage. Therefore, the information presented here shows a direction for the development of encapsulation systems capable of stabilizing different enzymes and obtaining better performance during application.

Chitosan-alginate beads as encapsulating agents for Yarrowia lipolytica lipase: Morphological, physico-chemical and kinetic characteristics.

Extracellular lipase from Yarrowia lipolytica was immobilized by ionotropic gelation with alginate and chitosan as encapsulating agents. Photomicrographs revealed a collapsed and heterogeneous surface of these microcapsules due to freeze-drying process. The optimum reaction temperature for the microencapsulated lipase (40 °C) was higher than for free lipase (35 °C) as well as the optimum pH (8.0 and 7.5, respectively). The study of the reaction kinetics showed that a higher maximum reaction rate (Vmax) (221.1 U/mg) for the free lipase in comparison to the immobilized form (175.3 U/mg). A protective effect of the microcapsule was detected in the storage of the enzyme at room temperature, as after 75 days 35% of activity was maintained for the microcapsules, while no activity remained after 15 days with the free enzyme. Lower values for inactivation constant (kd) and increase in half-life for immobilized lipase showed that lipase microencapsulation favored the thermostability of this enzyme.

Microencapsulation of tiger nut milk by lyophilization: Morphological characteristics, shelf life and microbiological stability.

Tiger nut milk is a nutrient rich drink with great commercialization potential. However, it is highly perishable. Microencapsulation of tiger nut milk by a blend of inulin and modified tiger nut starch resulted in a product with good characteristics. The microspheres of lyophilized tiger nut milk were spherical with and average particle size of 1.01 µm. It's thermal degradation occurred above 346 °C, denoting an excellent thermal resistance. There was no significant structural alteration in the active material after microencapsulation and no loss of stability within 60 days, which confirms that this process enables the preservation of freshness and chemical characteristics of tiger nut milk. During 30-90 days, vitamin C contents were stable in the presence or absence of light. Microsphere with tiger nut milk presented a shelf life of 60 days. Total aerobic mesophiles and total fungi counts were below 106 CFU/mL, showing good microbiological stability.