Food thermal property prediction as effected by temperature and composition
Abstract
Thermal properties of foods (thermal conductivity, thermal diffusivity, density, and specific heat) are heavily dependent on temperature and composition. The thermal properties of pure component solids were determined by the proposed model, which was based on the weight fraction and the thermal properties of major pure components of food products, at a temperature range of $-$40$\sp\circ$C to 150$\sp\circ$C from the experimental values of 10%, 30% and 60% solid content suspensions. The major components of food products considered were proteins (albumin, casein, whey protein, meat protein and gluten), lipids (milk fat, vegetable oil, lard and corn oil), carbohydrates (dextrose, lactose, sugar and starch), fibers (cellulose and pectin), and milk salts. A modified probe method was used to measure thermal conductivity and thermal diffusivity of pure component suspensions of each major component of food products for the solids content range of 10% to 60% at the temperature range of $-$40$\sp\circ$C to 150$\sp\circ$C and the same properties in food products. Density and specific heat of the samples were measured by a volumetric pycnometer and a differential scanning calorimeter, respectively. General mathematical models were developed by an optimization technique for the thermal properties of food products on the basis of weight fraction which is a easily measurable factor compared to the volume fraction. For the frozen foods, the unfrozen water factions were predicted by the product freezing point depression. The thermal property values by the proposed models of pure major components in this study were within 3.9% error to the literature values of liquid foods and within 4.7% error to the experimental values determined for evaporated milk, orange juice, and bratwurst sausage. The thermal property models developed in this study can be used to predict the properties of all food products with the weight fractions of major pure components in foods.
Degree
Ph.D.
Advisors
Okos, Purdue University.
Subject Area
Agricultural engineering
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