Catalase stability in polyelectrolytes microcapsules of alginate and pectin mixture in combination with trehalose

SANTAGAPITA, PATRICIO R.; MAZZOBRE, M. FLORENCIA; BUERA, M. PILAR

Córdoba, Argentina

Congreso; Congreso Internacional de Ciencia y Tecnología de los Alimentos; 2009

Ministerio de Ciencia y Tecnología de Córdoba y Universidad Nacional de Córdoba

Microencapsulation of food ingredients, enzymes, cells, or other materials is a very versatile technique used in food technology, pharmaceutics and cosmetic industry. The encapsulation procedure takes advantages of the immobilization process, which facilitates a wide variety of chemical and biological process. On the other hand, the conservation of labile biomolecules is generally performed in dehydrated or frozen media, being saccharides (especially trehalose) among of the most used excipient. Catalase is an enzyme of high technologically impact which catalyzes the decomposition of hydrogen peroxide into water and oxygen; the former is used as an active bactericide, and it must be removed after used. Then, having the enzyme in a microcapsule could be an enormous advantage in terms of reuse and recuperation. Alginate and pectin are two of the most popular polyelectrolytes used for microcapsule preparation, but there was no data of a combination of them to prepare microcapsules. Both polyelectolytes are anionic, and form gel structures in contact with CaCl2 solution. The purpose of this work was to evaluate the stability of catalase in microcapsules of polyelectrolytes exposed to a variety of treatments, such as freezing, freeze drying and thermal incubation. Alternatively, trehalose was incorporated in the internal or/and external media, leading to different properties of rehydration and stabilization. The microcapsules were obtained by dropping the alginate + pectin + enzyme mixture on a CaCl2 solution with a syringe, under continuous stirring. The formed beads were frozen for 24 h at -26 °C and then freeze dried for 24 h. Then, dehydrated and wet beads were incubated at 55 °C. After each treatment, the remaining activity of the enzyme was determined (by spectrophotometric method) and microscopic observations were performed. Spherical microcapsules were obtained with an average diameter of 1-2 mm. The microencapsulation of catalase markedly increased its stability to thermal treatment, in comparison with the enzyme stability in the polyelectrolyte solution prior to bead formation (50 % of the activity was conserved in the microcapsules while no activity was detected in the solution). After freezing and/or freeze drying, the microcapsule structure was maintained. The inclusion of trehalose in the internal media had a greater impact on enzyme stability than its inclusion in the external media, both in wet and dried beads, probably do to an enzyme-trehalose interaction. Trehalose can interact with catalase by hydrogen bonds and can occupy void spaces in a better way than polyelectrolytes due to its reduced size.