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Monoacylglycerols (MAG), diacylglycerols (DAG) and triacylglycerols (TAG) are emulsifiers widely used in the food, pharmaceutical and cosmetic industries. These molecules can be synthesized using lipase as biocatalyst resulting in more pure and not degraded lipids. The objective of this paper was the esterification of caprylic acid and glycerol, using an immobilized sn-1,3-specific lipase from Rhizomucor miehei (Lipozyme RM IM) as biocatalyst to produce MAG, DAG and TAG. Reactions were carried out in a batch-type reactor at different temperatures and molar ratios of caprylic acid to glycerol. A $$2^{2}$$ factorial experimental design was chosen to investigate the effects of temperature from 30 to $$70 \,^{\circ }\hbox {C}$$ and molar ratios of glycerol to caprylic acid ranging between 1:2 and 1:6. The reaction yield was calculated from the remaining free fatty acids in the reaction medium, as determined by titration, and from the amount of caprylins produced, as determined by gas chromatography. Response surface methodology was employed to evaluate the optimal conditions to obtain the highest yield. The chosen reaction parameters yielded an adequate production of MAG, DAG and TAG, and the highest output (88%) was achieved under intermediate temperature/molar ratio ( $$50\,^{\circ }\hbox {C}$$ /1:2) conditions. In order to reduce production costs, reuse of lipase was evaluated by running three consecutive batches on a microfiltration-membrane-coupled bioreactor and on a regular bioreactor (no membrane). Results showed the microfiltration-membrane-coupled bioreactor to be more efficient, since there was only a 10% decrease in the initial reaction yield after three consecutive esterification reactions.

O glicerol é um dos resíduos mais abundantes na produção do biodiesel e sua disponibilidade está atrelada diretamente à intensidade de produção do biocombustível. Apesar da diversidade de aplicações industriais para o glicerol, a procura de novos usos é estimulada pela crescente disponibilidade e forte diminuição do seu custo. Desta forma, este trabalho procurou contribuir com uma nova alternativa para a aplicação do excesso deste poliálcool, propondo sua esterificação com o ácido caprílico - um antimicrobiano natural. A produção de monocaprilina, dicaprilina e tricaprilina a partir da esterificação do glicerol com ácidos graxos utilizando a lipase imobilizada Lipozyme RM IM sn-1,3 específica teve seu rendimento otimizado por um planejamento experimental do tipo DCCR - Delineamento Composto Central Rotacional. Assim, dois fatores foram considerados no planejamento experimental: temperatura e proporção molar de ácido caprílico. Estas variáveis foram estabelecidas em dois níveis nos seguintes intervalos: a temperatura variou de 30 a 70°C e a proporção molar (ácido caprílico:glicerol) de 2:1 a 6:1, resultando em 11 experimentos. O tempo foi fixado em 6 horas. A porcentagem total de acilgliceróis pode ser obtida tanto por titulação quanto por cromatografia gasosa. O planejamento experimental demonstrou ser eficiente, pois, obteve-se alto rendimento em produtos na maioria dos experimentos, onde se pôde notar que a melhor condição para produção de caprilinas ocorreu quando se combinou baixa temperatura e baixa proporção molar de ácido caprílico no substrato glicerol. As análises quantitativas revelaram que o melhor rendimento resultou em 87,8% de caprilinas. Adicionalmente, a síntese de caprilinas foi estudada em dois tipos de reatores descontínuos: munido ou não de membrana de microfiltração, para avaliar a possibilidade de reuso do biocatalisador. As reações ocorreram na melhor condição experimental do planejamento proposto e em três ciclos de bateladas sucessivas. A membrana de microfiltração aliada à enzima imobilizada demonstrou ser um instrumento importante para diminuir o custo da reação visto que, com seu uso a enzima reteve 82,7% de sua atividade inicial. Glycerol is one of the most abundant residues in biodiesel production and its availability is directly linked to the intensity of biofuel production. Despite the diversity of industrial applications for glycerol, the demand for new uses is stimulated by increasing the availability and strong decrease of its cost. Thus, this study intended to propose a new alternative for using this polyalcohol, through its esterification with caprylic acid - a natural antimicrobial. The reaction was catalyzed by immobilized lipase (Lipozyme RM IM, sn-1-3 specific®) resulting mono, di and tricaprylin. The reactions were designed by using the statistical method called \"Delineation Central Composite Rotational (DCCR)\". Taking into account the variation of two parameters, i.e., temperature (from 30ºC to 70ºC) and molar ratio caprylic acid/glycerol (from 2:1 to 6:1) the DCCR pointed to the realization of eleven tests. The time was set at 6 hours. The total percentage of acylglycerols were obtained either by titration or by gas chromatography. The experimental design showed to be efficient because a high yield was achieved in most of the experiments, and the best condition for caprylins production occurred when low temperature and low caprylic acid/glycerol molar ratio were combined. Quantitative analysis revealed that the best yield resulted in 87.8% of caprylins. Additionally, caprilyns synthesis was studied by using a batch reactor coupled or not with microfiltration membrane. The reactions were performed under the best experimental condition pointed out by the DCCR and the enzyme reutilized threefold through successive batches. After that the enzyme retained about 83% of its original activity.