Inverted sugar production by immobilized invertase and its mathematical modeling and simulation
摘要
Invertase (E.C 3.2.1.26), extracted from commercial yeast (ICY), was immobilized on glyoxyl-agarose. Four assays were tested to assess the effect of the load protein offered per gram of gel by ICY activity and the production of reducing sugars: (I) not immobilized-ICY at 25 °C, (II) not immobilized-ICY at 40 °C, (III) immobilized-ICY on glyoxyl-agarose (2.8 mg protein offered per gram of gel), and (IV) immobilized-ICY on glyoxyl-agarose (1.4 mg protein offered per gram of gel), both at 40 °C. Immobilization surpassed the activity of non-immobilized-ICY. The greater the amount of immobilized enzymatic protein, the greater the specific activity (524.3 ± 14.2 U mg−1) with reducing sugars production of 3313.8 ± 89.6 mg mL−1. Saccharose hydrolysis both in vitro and in the bioreactor followed first-order kinetics and the kinetic parameters were: 0.0012 ± 0.0001 (in vitro at 25 °C), 0.0101 ± 0.0034 (in vitro at 40 °C), 0.0022 ± 0.0003 (bioreactor at 32 °C), and 0.0028 ± 0.0003 min−1 (bioreactor at 35 °C). The kinetic model for batch bioreactors was adequate to represent the hydrolysis of saccharose up to 40 min of reaction. In the bioreactor, a conversion of 13% at 32 °C and 15% at 35 °C of saccharose was achieved using a flow rate of 0.364 L.h−1 and 70 min of reaction. By simulation for bioreactor model, it would be possible to achieve a higher yield after 7 h of reaction, which suggests that it can be used at a commercial level.