Foods may be considered as mixtures of the following major components: water, protein, fat, carbohydrate and ash (i.e. non-combustible solids such as minerals etc). Some foods may contain a significant volume fraction of ice and/or air (porosity). Temperature is the most critical processing condition in solid and liquid phases although pressure can be significant too e.g. high pressure processing (HPP). The temperature-dependent thermal conductivities of the major food components were measured by Choi of other sources In general terms, the thermal conductivities of protein, fat, carbohydrate sand ash are similar; about three times lower than that of water, nine times lower than that of ice and ten times higher than
that of air. It is the dependence of the thermal conductivity of the food on structure that is accounted for by the thermal conductivity model. This study only considers models which are functions of the composition of the food and thermal conductivities of the major food components only, and do not involve any parameters which must be measured experimentally. For first approximations, one of two approaches.