Browsing by Subject "vacuum reactor"

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    Biocatalytic Synthesis of Polyglycerol Polyricinoleate: A Comparison of Different Commercial Lipases
    (Assoc. of Chemists and Chemical Engineers of Croatia, 2013-10) Ortega Requena, Salvadora; Gómez, José Luis; Bastida Rodríguez, Josefa; Máximo Martín, María Fuensanta; Montiel Morte, María Claudia; Gómez, María; Ingeniería Química
    In this work, the studies were carried out to select the most suitable lipase as catalyst for the esterification of polyglycerol with polyricinoleic acid to yield polyglicerol polyricinoleate (PGPR), a valued-added, biobased food emulsifier are described. The enzymes assayed were lipases from Rhizopus arrhizus, Rhizopus oryzae and Mucor javanicus, previously selected because of their suitable activity and moderate cost. First, reaction was catalyzed by free lipases in a batch reactor and the influence of different operating conditions (initial water content, amount of enzyme and temperature) on the progress of the reaction was studied. Next, the three lipases were immobilized by physical adsorption on the anion exchange resin, Lewatit MonoPlus MP 64, providing derivatives with a high activity and stability. Recovery of the immobilized derivative from the reaction medium was conducted with very good yields (up 99%) and no loss of activity of the derivative with successive uses was proved. Finally, a high performance reactor, which operates at low pressure and with a dry atmosphere, was used to synthesise PGPR using the immobilized enzymes. Both Rhizopus arrhizus and Rhizopus oryzae lipases allowed the production of a PGPR which fulfils the “specific purity criteria on food additives other than colours and sweeteners” established by the Commission of the European Communities, with an acid value of 4.91 and 5.31 mg KOH/g respectively.
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    Esterification of polyglycerol with polycondensed ricinoleic acid catalysed by immobilized Rhizopus oryzae lipase
    (Springer, 2012-12-23) Ortega Requena, Salvadora; Máximo Martín, María Fuensanta; Montiel Morte, María Claudia; Murcia Almagro, María Dolores; Arnold, G.; Bastida Rodríguez, Josefa; Ingeniería Química
    The enzymatic method for synthesising polyglycerol polyricinoleate (PGPR), a food additive named E-476, was successfully carried out in the presence of immobilized Rhizopus oryzae lipase in a solvent-free medium. The great advantage of using the commercial preparation of Rhizopus oryzae lipase is that it is 10 times cheaper than the commercial preparation of Rhizopus arrhizus lipase, the biocatalyst used in previous studies. The reaction, which is really a reversal of hydrolysis, takes place in the presence of a very limited amount of aqueous phase. Immobilization of the lipase by physical adsorption onto an anion exchange resin provided good results in terms of activity, enzyme stability and reuse of the immobilized derivative. It has been established that the adsorption of Rhizopus oryzae lipase on Lewatit MonoPlus MP 64 follows a pseudo-second order kinetics, which means that immobilization is a process of chemisorption, while the equilibrium adsorption follows a Langmuir isotherm. The use of this immobilized derivative as catalyst for obtaining PGPR under a controlled atmosphere in a vacuum reactor, with a dry nitrogen flow intake, allowed the synthesis of a product with an acid value lower than 6 mg KOH/g, which complies with the value established by the European Commission Directive. This product also fulfils the European specifications regarding the hydroxyl value and refractive index given for this food additive, one of whose benefits, as proved in our experiments, is that it causes a drastic decrease in the viscosity (by 50%) and yield stress (by 82%) of chocolate, comparable to the impact of customary synthesised PGPR.