Blast-cooling of beef-in-sauce catering meals: numerical results based on a dynamic zero-order model

Abstract

Beef-in-sauce catering meals under blast-cooling have been investigated in a research project which aims at quantitative HACCP (hazard analysis critical control point). In view of its prospective coupling to a predictive microbiology model proposed in the project, zero-order spatial dependence has proved to suitably predict meal temperatures in response to temperature variations in the cooling air. This approach has modelled heat transfer rates via the a priori unknown convective coefficient hc which is allowed to vary due to uncertainty and variability in the actual modus operandi of the chosen case study hospital kitchen. Implemented in MS Excel®, the numerical procedure has successfully combined the 4th order Runge-Kutta method, to solve the governing equation, with non-linear optimization, via the built-in Solver, to determine the coefficient hc. In this work, the coefficient hc was assessed for 119 distinct recently-cooked meal samples whose temperature-time profiles were recorded in situ after 17 technical visits to the hospital kitchen over a year. The average value and standard deviation results were hc = 12.0 ± 4.1 W m-2 K-1, whilst the lowest values (associated with the worst cooling scenarios) were about hc » 6.0 W m-2 K-1.

Numerical methods to biosystems and food engineering students: Hands‐on practices and cross‐disciplinary integration

“…In thermal problems with low Biot numbers (Bi <0.1), heat conduction is much faster than heat convection so that uniform temperature can be assumed within the given body and lumped-parameter analysis can be applied [1]. Inspired by the blast-cooling of catering meals examined in [12], students are asked to obtain temperature-time profiles T(t) of food under cooling as ruled by the following 1st-order ordinary differential equation (i.e., Newton's law of cooling):…”

“…The blast-cooling of catering meals [12] is again referred in this lecture but it is discussed that temperature may vary inside foodstuff. This thermal food processing was studied in [13] via finite differences method (FDM), whose fundamentals [1] are taught to students together with different types of boundary conditions (e.g., Dirichlet, Neumann, Robin, radiative heat transfer).…”