Shear-induced inactivation of alpha-amylase in a plain shear field.
A newly developed shearing device was used to study shear-induced inactivation of thermostable alpha-amylase in a plain shear field, under conditions comparable to extrusion. The results show that the inactivation can be described well with a first-order process, in which the inactivation energy largely depends on the shear stress, instead of specific mechanical energy or strain history. The resulting dependency of the rate of inactivation on the shear stress is very strong and nonlinear, which leads to the conclusion that in many cases the maximally applied shear stress determines the inactivation. Quantification of the inactivation rates gives design criteria for the application of enzymes in more viscous systems than conventionally used, provided that the reactor is designed such that no peak shear stresses occur.
Department of Food and Bio Process Engineering, Wageningen University, The Netherlands, Bomenweg 2, 6703 HD Wageningen.
Mark E
ME
van der Veen
Daan G
DG
van Iersel
Atze J
AJ
van der Goot
Remko M
RM
Boom
D004795:Enzyme Stability; D007700:Kinetics; D013314:Stress, Mechanical; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000516:alpha-Amylases