Lipase livre e imobilizada em quitosana : caracterização e potencial de aplicação em reações de hidrólise e síntese

• Ano de defesa: 1999
• Autor(a) principal: Pereira, Ernandes Benedito
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Departamento de Engenharia Química; Programa de Pós-Graduação em Engenharia Química; UEM; Maringá, PR; Centro de Tecnologia
• Palavras-chave em Português: Desenvolvimento de processos; Quitosana; Brasil.; Engenharias; Engenharia Química
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/3779

The objective of this work was the production of immobilized lipase derivatives on chitosan (cheap support), aiming their application on hydrolytic and synthetic reactions. The derivatives were obtained by physical adsorption and covalent binding using hexane as dispersion medium. Two types of chitosan (analytical and pharmaceutical grade) were used for immobilizing lipase from microbial source (Candida rugosa) and animal cell (porcine pancreas). The best results with respect to the recovery of total activity afier immobilization (protein retention of 80% and immobilization efficiency of 15%) were obtained for microbial lipase and pharmaceutical grade chitosan. This set was selected for further immobilization studies, including fiilly characterization of the immobilized derivative under aqueous and non-aqueous media. Under aqueous medium, a comparative study between free and immobilized lipase was provided in terms of p11, temperature, thermal stability and operational stability. Slightly lower value for optimum p11 (6.0) was found for the immobilized form in comparison with that attained for the free lipase (7.0). The optimal reaction temperature shifted from 37°C for the free lipase to 50°C for the chitosan lipase. The patterns of heat stability indicated that the immobilization process tends to stabilize the enzyme. The half life of the free lipase at 55°C was equal to 0.41 h (K1= 1.7 h1), whereas for the immobilized lipase was found to be 0.86 h (kd = 0.81 h-1). The operation stability of the immobilized lipase was tested by repeated assays (olive oil hydrolysis for 10 mm! 3 7°C) and a half-life of 5 hours was observed. Under organic medium, the potential application of the immobilized derivative was verified by testing its performance on the esterification reaction using several aliphatic alcohols and fatty acids. The system butanol (ButOH)I butyric acid (Abut) was selected for a detailed study employing statistical experimental design. A full 2 factorial design at two levels was used to determine the influence of three factors: temperature (37 and 50°C), amount of lipase (0.25 and 0.5g) and molar ratio between Abut: ButOH (1 and 2) on the variable response (yield of ester). Three runs were carried out at the center point level for experiment error estimation. The results were analyzed by Analysis of Variance (ANOVA) and the most significant main effect on the formation of butyl butyrate was the initial lipase amount. For the experiment range studied, there was no evidence on the interaction of the lipase amount with the other two factors. The immobilized lipase was used repeatedly (seven times) in batch esterification reactions of butanol with butyric acid and the activity loss in long-term was about 28%, however there was a significant decrease on the esterification yields (83%). This suggested that no desorption of the enzyme from the support occurred. It is therefore likely that reactants and product bind to the solid enzyme phase resulting in drastic changes in the enzyme synthetic activity for the next cycle. In this sense, techniques allowing the removal of these potential inhibitors from the enzyme solid phase, are expected to improve the operational stability of this immobilized derivative.