Implementação de reator de leito fixo recheado com biomassa microbiana encapsulada em alginato para a produção de frutooligossacarídeos

Abstract

Fructooligosaccharides (FOS) are short chain oligomers, consisting of fructose polymers linked to sucrose. FOS are classified as prebiotics due to the excellent physiological benefits caused by their regular intake. The promising results achieved by the application of fructosyltransferases (FTase) from the mycelial fungus Aspergillus oryzae immobilized in a calcium alginate matrix in the production of FOS in a batch regime, support the transposition of the process to the continuous flow regime. Therefore, this work proposed the implementation of an enzymatic fixed bed reactor (PBR) applied in the production of FOS via transfrutosylation reaction. The combined influence of temperature and flow on enzymatic activity was investigated by means of a central rotational composite design with triplicate at the central point. The effects of the substrate concentration and the volumetric flow rate on the activities of the biocatalyst were also studied and the kinetic parameters of the enzymatic reaction were obtained. The mass transfer parameters were estimated and the operational stability of the process was evaluated in the absence and presence of recycle. The response surfaces and contour curves were constructed and the reaction conducted at 50°C was obtained as the best operational parameters, with the reactor fed with sucrose solution 400g.L-1 at a flow rate of 7.5mL.min-1. Regarding the enzymatic kinetics, the experimental data were adjusted by Hill's corporate model, indicating positive affinity between enzyme and substrate. The external mass transfer coefficient (k_c=1,0x10^(-2) m.s^(-1)) and the effectiveness factor (η_m=0.974), calculated for the internal mass transfer to the particle, demonstrate the low limitation imposed by the mass transport steps on the rate of reaction development. The study of operational stability indicated 96% retention of the enzymatic-catalytic activity after 12h of the process. Therefore, it can be concluded that the implementation of PBR reactor, filled with biocatalyst encapsulated in calcium alginate gel, has shown promise for application in the enzymatic production of FOS.