Modeling the kinetics of the pectin methylesterase catalyzed de-esterfication of pectin in frozen systems.
The applicability of the William, Landel, and Ferry (WLF) equation with a modification to take into account the effect of melt-dilution and an empirical log-logistic equation were evaluated to model the kinetics of diffusion-controlled reactions in frozen systems. Kinetic data for the pectin methylesterase catalyzed hydrolysis of pectin in four model systems with different glass transition temperatures: sucrose, maltodextrin (DE = 16.5-19.5), carboxymethylcellulose (CMC) and fructose in a temperature range of -24 to 0 degrees C were used. The modified WLF equation was evaluated with a concentration-dependent glass transition temperature (T(g)) as well as the glass transition temperature of the maximally freeze-concentrated matrix (T(g)') as reference temperatures. The equation with temperature-dependent T(g) described the reaction kinetics reasonably well in all the model systems studied. However the kinetics was better described by a linear relationship between log(V(0)/V(0ref)) and (T - T(ref)) in all cases except CMC. The log-logistic equation also described the kinetics reasonably well. The effect of melt-dilution on reactant concentration was found to be minimal in all cases.
Terefe
Netsanet Shiferaw
NS
Department of Food and Microbial Technology, Laboratory of Food Technology, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium.
Nhan
Minh Tri
MT
Vallejo
David
D
Van Loey
Ann
A
Hendrickx
Marc
M
D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D002384:Catalysis; D003198:Computer Simulation; D004789:Enzyme Activation; D004951:Esterification; D005615:Freezing; D007700:Kinetics; D000432:Methanol / Q000138:chemical synthesis*; D008956:Models, Chemical; D010368:Pectins / Q000737:chemistry*; D044367:Phase Transition; D044366:Transition Temperature
D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D000432:Methanol