Statistical and kinetic modeling of Aspergillus niger inulinase fermentation from carob extract and its partial concentration

Abstract

This study aimed to optimize inulinase production conditions from carob extract by using the Box-Behnken Design of Response Surface Methodology, to purify partially with ultrafiltration, and to model kinetically the inulinase fermentation. Based on the results, the optimal conditions were 250 rpm agitation speed, 2.3% inoculum size (v/v), and 135 mL medium volume, which yielded 1560.17 U/mL inulinase activity, 1198.36 U/mL invertase-type activity, 1.30 I/S ratio, 163.06 U/mL/d maximum inulinase fabrication rate, and 193.37 U/mL/d maximum invertase-type fabrication rate. With the ultrafiltration process, the inulinase and invertase-type activities were increased to 6278.69 and 7622.39 U/mL with 1.19 and 1.50 purification coefficients, respectively. Regarding modeling with the Luedeking-Piret model, enzyme and protein productions were not related to the substrate depletion due to negative a values. Consequently, carob extract can be evaluated for the fabrication conditions of A. niger inulinase and the purified enzyme can be used for the fabrication of fructooligosaccharides.