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Hydrolysis of lactose in skim milk by immobilized β‐galactosidase in a spiral flow reactor
Author(s) -
Bakken Andrew P.,
Hill Charles G.,
Amundson Clyde H.
Publication year - 1989
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260331005
Subject(s) - lactose , chemistry , continuous stirred tank reactor , skimmed milk , chromatography , residence time distribution , lactase , hydrolysis , aspergillus oryzae , mutarotation , substrate (aquarium) , biochemistry , organic chemistry , enzyme , mineralogy , food science , inclusion (mineral) , oceanography , geology
Abstract β‐galactosidase from Aspergillus Oryzae immobilized in a spiral flow reactor was used to effect the hydrolysis of the lactose component of skim milk. Residence time distribution measurements were used to assess the amount of longitudinal dispersion occurring as a consequence of the spiral flow pattern and the semiporous nature of the polymeric material used to construct the spiral. It was possible to model the flow conditions as tubular flow with a Peclet number that was a linear function of the reactor space time. Nonlinear regression methods were used to determine the kinetic parameters of three proposed enzymatic rate expressions. The best fit of the data was obtained using a rate expression containing separate terms for competitive inhibition of the reaction by both the a and β anomers of galactose. This kinetic model also incorporates the kinetics of the mutarotation between these forms. At 30°C and a space time of 7 minutes, 80% of the lactose present in skim milk can be converted to glucose and galactose.