Escalado de procesos fermentativos aerobios en biorreactores tipo tanque agitado : Escalado de la fermentación para la obtención de vinagre de naranja agria (Citrus aurantium L.) con acetobacter sp.

Abstract

In Ecuador, orange production does not meet the economic requirements of farmers who are affected by overproduction, waste generated during the marketing chain, and low sales prices; therefore, there is a need to add value to this fruit. In the present study, two scale-up protocols are accomplished to produce bitter orange (Citrus aurantium L.) vinegar using Acetobacter sp. in laboratory and pilot model scales with 15 and 110 L volume sized by means of geometric similarity criteria, and also keeping constant the oxygen transfer coefficient (KLa) and the dissolved oxygen concentration (DO). These parameters were estimated by theoretical and empirical equations based on operating conditions of 400 rpm, 25 °C, and 0. 3 VVM, determined through literature review, in a prototype STR bioreactor with an operating volume of 1.37 L and a Rushton-type double stirring system. A value of 31.5 h-1 was determined for KLa in the prototype scale, which to remain constant requires the laboratory and pilot scale to operate at 506 and 164 rpm respectively. Similarly, to hold an OD of 2.33 ppm, the laboratory and pilot scales must operate at 563 and 156 rpm respectively. In all cases, an aeration rate of 0.1 VVM is contemplated. The operating conditions found satisfy acceptable ranges that ensure adequate bacterial growth by increasing power consumption and tip speed to compensate a significant reduction of the pumping number.