On the Thermal Effusivity of Bovine Milk

Daniel Acosta-Avalos,Daniel Soares Velasco

doi:10.5402/2012/614086

Daniel Acosta-Avalos, Daniel Soares Velasco

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https://doi.org/10.5402/2012/614086

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Journal: ISRN Thermodynamics	Publication Date: Dec 20, 2012
Citations: 4	License type: CC BY 3.0

Affiliation: Centro Brasileiro de Pesquisas Físicas

Abstract

Thermal diffusivity, conductivity, and effusivity are parameters that can be measured using photoacoustic techniques. Both thermal diffusivity and conductivity have already been measured for bovine milk. To complete its thermal characterization, this paper deals with the thermal effusivity of commercial bovine milk with a different fat content. The thermal effusivity ε obtained for skimmed, partly skimmed, and whole milks is 0.153 W cm−2 s1/2 K−1, 0.144 W cm−2 s1/2 K−1, and 0.140 W cm−2 s1/2 K−1, respectively, with the uncertainty being less than 5%. It was observed that the thermal effusivity decreases with the increase in the fat content. For the first time, it is observed that the thermal effusivity is a linear function of the logarithm of the fat content. The comparison of our results with previous results for milk from Slovakia revealed different thermal effusivity values. This might be due to regional differences in the milk composition and could be used as a criterion to identify the milk provenience.

Highlights

IntroductionThermal effusivity ε, termed thermal impedance, measures the ability of matter to exchange heat with its environment [1]
The thermal conductivity k (W cm−1 K−1), thermal diffusivity α, and thermal effusivity ε (W cm−2 s1/2 K−1) are three dynamic thermophysical parameters unique to each material and related among them through the relation ε = k/α1/2
The thermal effusivity ε was calculated from the plots shown in Figure 2, showing the variation of |QN |2 as a function of1/2 and (4) was used to fit the data and calculate the adjustable parameter b = εliq/εAl

Summary

Introduction

Thermal effusivity ε, termed thermal impedance, measures the ability of matter to exchange heat with its environment [1]. These thermal parameters present high sensitivity to changes in microstructural variables, composition, temperature, and specific processing conditions. Handling these thermal parameters data contributes to refinements in optimization of food processing conditions, techniques, and equipment, resulting in improved quality and storage of foods as milk. Nutritious liquid that contains several substances that are either in solution, suspension, or emulsion in water. The amount of water in milk reflects that balance [2]

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