Stochastic modeling and visualization of a tortilla chip

Abstract

Monte Carlo simulation was used as an alternative technique and stochastically modeled component distribution in a tortilla chip. The components included oil, water, gas and solids. A conditional percolation approach was used to model pore size distribution and predict thermal conductivity in a tortilla chip fried at 190⁰C for 60 seconds. The results were simulated using Ensight[TM] (CEI, Morrisville, NC), a scientist's plotting tool. The individual components were considered as scalars on a three-dimensional mesh and isosurfaces were plotted across them. Isosurfaces are surfaces that follow a constant value of a variable through three-dimensional elements. Isosurfaces are to three-dimensional elements what contour lines are to two-dimensional elements. The component clusters were counted and their mean size determined. The clusters were further analyzed for different frying conditions. Similar models were constructed for freeze-dried and steam-baked tortilla chips. The model predicted maximum oil absorption in a control tortilla chip (once baked) during the first 10 seconds of frying. Simultaneously, maximum water evaporation was observed during the first 10 seconds of frying. Maximum pore expansion occurred between 30 and 40 seconds of frying. Steam baking the tortilla chip gelatinization. This surface prevented water evaporation as well as oil absorption. The moisture provided for an increasing porosity in the product (47.12% to 54.04%). The freeze-dried tortilla chip had higher internal oil content due to smaller pores spread over the matrix. The smaller pores are due to the absence of a tight barrier along the tortilla's surface, as freeze-drying does not cause starch gelatinization (no heat treatment prior to frying). The pore volume distribution in a control tortilla chip cannot be modeled effectively using the percolation approach, because pore interconnectivity increases considerably above a threshold percolation volume (p[]) (between 34.5% and 46.80%). Thermal conductivity in a control (once baked) tortilla chip was modeled effectively using the percolation approach. The product was assumed to be a three-component mixture, the components being air, oil, and solids bound by water. The average thermal conductivity for a frying time of 60 seconds and a frying temperature of 190⁰C was 0.17 W/m⁰C.