Thermal Conductivity of Fresh Lamb Meat, Offals and Fat in the Range ‐40 to +30oC: Measurements and Correlations
ABSTRACT The thermal conductivity of fresh lamb meat, offals and fat was measured over the temperature range -40°C to +30°C using a guarded hot plate apparatus. Simple empirical equations were presented for the conductivity of high-moisture (65 to 80%) meat and offals. With independently obtained values of physical parameters, several theoretical models were tested to sec if thermal conductivity could be calculated from composition and temperature. Over a wide range of compositions and temperatures, best predictions (in terms of mean, standard deviation and range of errors) were obtained with Levy's modification to the Maxwell-Eucken equation. Its accuracy was not unduly sensitive to the uncertainties in the values of the physical parameters, the prediction errors remaining in the range ± 10% for all reasonable values of the latter.
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ABSTRACT: Thermal conductivity values of meat samples with moisture contents between 4.73 and 79.47% (wet basis) and fat contents between 1.44 and 93.17% (wet basis) were measured at temperatures ranging from−30 to 25C using the line heat source probe method. Thermal conductivities of frozen meat samples were higher than the ones in the unfrozen state. Measured thermal conductivity values were mathematically interpreted as a function of temperature, moisture, protein and fat contents by application of nonlinear regression analysis for frozen samples. Measured thermal conductivities were compared with the models given in the literature. Levy's model provided more accurate predictions than the others in the frozen state and parallel model showed the best predictions in the unfrozen state. For unfrozen state, thermal conductivity was found to increase with moisture content and decrease with fat content, although in the frozen state, thermal conductivity increases with decreasing temperature.PRACTICAL APPLICATIONSThermal properties of food products are key factors in the design of thermal processes such as cooling or heating for food preservation. Analysis, design and simulation of food freezing and storage process demands reliable and easily accessible thermal property data across a wide range of temperatures, particularly below freezing. Thermal conductivity is an important property for freezing and thawing applications. An accurate knowledge of thermal conductivity as a function of composition and temperature is important to determine process parameters involved in heat transfer. Then, the total amount of heat to be added or removed from a product in a specific process can be determined as well as the rate at which heat can be added or removed. The model developed in this study can be used to model heat transfer calculations in freezing, thawing and storage of meats.Journal of Food Processing and Preservation 06/2010; 34(3):425 - 438. · 0.45 Impact Factor
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ABSTRACT: A set of well-known generic models to predict the thermophysical properties of food from its composition at atmospheric conditions was adapted to work at any pressure. The suitability of the models was assessed using data from the literature for four different food products, namely tomato paste, potato, pork, and cod. When the composition of the product considered was not known, an alternative was proposed if some thermal data at atmospheric conditions were available. Since knowledge on the initial freezing point and ice content of food are essential for the correct prediction of its thermal properties, models for obtaining these properties under pressure were also included. Our results showed that good predictions under pressure, accurate enough for most engineering calculations can be made, either from composition data or using known thermal data of the food considered at atmospheric conditions. All the equations and coefficients needed to construct the models are given throughout the text, thus readers can compose their own routines. However, these routines can also be downloaded free at http://www.if.csic.es/programas/ifiform.htm as executable programs running in Windows.Critical reviews in food science and nutrition 04/2010; 50(4):344-68. · 3.73 Impact Factor
- Journal Des Maladies Vasculaires - J MAL VASCUL. 01/2010; 35(5):320-320.