Isothermal and Non-isothermal Kinetic Models of Chemical Processes in Foods Governed by Competing Mechanisms

Abstract

A process or reaction that peaks at high temperatures but not at low ones indicates competition between synthesis and degradation. A proposed phenomenological model composed of a decay factor superimposed on a growth term can describe both. Temperature elevation shortens the two subprocesses' characteristic times and increases their rates. The degradation's characteristic time relative to the experiment's determines whether a peak is observed. All of the parameters determine the peak's height and shape as can be seen in two interactive Wolfram demonstrations on the Web. Detailed knowledge of the underlying mechanisms is unnecessary for the model's construction, and uniqueness is not a prerequisite either. However, different expressions might be needed for ongoing processes and ones initially undetectable. The model's applicability is demonstrated with published results on very different reactions in foods. In principle, it can be converted into a dynamic rate equation for simulating a process's evolution under non-isothermal conditions.

Artificial soils reveal individual factor controls on microbial processes

“…4h ). To quantify differences in AHL sensing dynamics, the ratiometric (CH3Br/CO2) data was fit to an exponential growth and decay model to calculate the maximum CH3Br/CO2 signal ( A ) and the time for half maximum gas accumulation ( T1/2 ) (Peleg et al, 2009). We observed that A and T1/2 both vary with soil particle size.…”

“…We fitted the AHL pulse in soils after normalization (see statistics section) to a model using a multiplication of two Kohlraush functions, or stretched exponential functions as described in Peleg et al, 2009 and shown in Eq 3:…”

Application of bio-inspired optimization algorithms in food processing

“…Food process industries generally deal with dynamic (more often) and static (less frequent instances) variables ( Peleg et al, 2009 ; Sendín et al, 2010 ). The mathematical approaches to an optimization problem in the area of food processing is mainly concerned with process designing, optimization of operational policy, and model calibration.…”

Wolfram Demonstrations: Free Interactive Software for Food Engineering Education and Practice

“…C [13], where B is the monitored product. Peleg et al [8] have recently discussed the phenomenology of such processes. They divided them into two types: those where the product's initial concentration is measurable (e.g., the Peroxide Value of a partly oxidized oil), or zero (e.g., the acrylamide concentration in yet to be fried potatoes or yet to be baked wheat dough).…”