Invertase hydrolyses sucrose, produces inverted sugar syrup, which is used, mainly, as a food composition in industries. To carry out the hydrolysis properly, the invertase should be stable in the soluble form through...Invertase hydrolyses sucrose, produces inverted sugar syrup, which is used, mainly, as a food composition in industries. To carry out the hydrolysis properly, the invertase should be stable in the soluble form through a considerable reaction period and recovered afterwards. The chosen reactor was a CSTR-type （continuous stirred tank reactor-type） coupled with an UFM （ultrafiltration-membrane）, the so-called MR （membrane reactor）. The varied parameters were： sucrose concentration （10-300 mM）, temperature （5-65 ℃）, reaction volume （14 mL and 65 mL）, stirring （100-500 rpm）, volumetric feeding rate （2.2-12 mL/h） and UFM MWCO （molecular weight cut off） （10, 20, 30, 50 and 100 kDa）. The invertase kinetic constants （KM = 23.5 mM; Vmax = 2,758 μmolgluJmin-mgprot; Ea = 9.1 kcal/mol） and the temperature deactivation energy （Ead= 20 kcal/mol） were calculated. Moreover, the invertase was unstable as the MR capacity diminished and the agitation increased up to 500 rpm most likely due to the damaging effect of shearing forces （present inside the MR） on the invertase molecule. Finally, both the MWCO and the chemical nature of the UFM affected the invertase stability along the hydrolysis. The enzyme stability increased as the UFM cut-off decreased, the highest value being observed with the 10 kDa-UFM.展开更多
文摘Invertase hydrolyses sucrose, produces inverted sugar syrup, which is used, mainly, as a food composition in industries. To carry out the hydrolysis properly, the invertase should be stable in the soluble form through a considerable reaction period and recovered afterwards. The chosen reactor was a CSTR-type （continuous stirred tank reactor-type） coupled with an UFM （ultrafiltration-membrane）, the so-called MR （membrane reactor）. The varied parameters were： sucrose concentration （10-300 mM）, temperature （5-65 ℃）, reaction volume （14 mL and 65 mL）, stirring （100-500 rpm）, volumetric feeding rate （2.2-12 mL/h） and UFM MWCO （molecular weight cut off） （10, 20, 30, 50 and 100 kDa）. The invertase kinetic constants （KM = 23.5 mM; Vmax = 2,758 μmolgluJmin-mgprot; Ea = 9.1 kcal/mol） and the temperature deactivation energy （Ead= 20 kcal/mol） were calculated. Moreover, the invertase was unstable as the MR capacity diminished and the agitation increased up to 500 rpm most likely due to the damaging effect of shearing forces （present inside the MR） on the invertase molecule. Finally, both the MWCO and the chemical nature of the UFM affected the invertase stability along the hydrolysis. The enzyme stability increased as the UFM cut-off decreased, the highest value being observed with the 10 kDa-UFM.
