Factorial design, preparation and characterization of new beads formed from alginate, polyphosphate and glycerol gelling solution for microorganism microencapsulation

Abstract

The growing environmental concern in all segments of society has aroused the interest of the scientific community in the search for alternatives to reduce the use of pesticides, getting highlighted the use of antagonists microorganisms, as species of Trichoderma. Despite many years of research, several challenges such as lack of formulations, storage and transport conditions, which reduce the viability of microorganisms, hamper the application of this technology in large scales. A polymeric formulation that retains the characteristics and properties of the antagonist is of fundamental importance for an efficient and effective control of the disease to be fought. Encapsulation into beads may be an alternative to provide protection and maintain the properties of these microorganisms. In this paper, applying the factorial design tool, was studied a formulation having as independent variables the proportion of sodium alginate, sodium polyphosphate and glycerol aiming to increase the water activity (aW) of the beads. The beads were prepared using the technique of drip by simple ionic gelation of biopolymers in solutions of CaCl2 (2M). Characterization of beads was held by FTIR spectrophotometer and thermogravimetric analysis. Results indicate that the greater proportion of polyphosphate formulation was more significant for a larger aW into the beads. Preliminary results show that beads formulation with alginate, polyphosphate and glycerol was able to maintain the viability of spores of Trichoderma sp. for 120 days when stored at room temperature. The water activity (aW) of the samples was evaluated and had different responses that depended on the composition of granules. The surface chart represents the responses of aW for Ca-AGP beads. Figure shows the Pareto diagram, where it can be seen that only the concentration of polyphosphate was significantly variable in aW response. The distribution of the residuals (values predicted by the model vs. observed values) showed that the deviations were normally distributed and that there was a satisfactory correlation between the theoretical and experimental values.