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Evaluation of Thermal Properties of Food Materials at High Pressures Using a Dual‐Needle Line‐Heat‐Source Method
Author(s) -
Zhu S.,
Ramaswamy H. S.,
Marcotte M.,
Chen C.,
Shao Y.,
Le Bail A.
Publication year - 2007
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2006.00243.x
Subject(s) - thermal diffusivity , thermal conductivity , materials science , heat capacity , thermal , composite material , calibration , relative humidity , analytical chemistry (journal) , thermodynamics , chemistry , chromatography , mathematics , statistics , physics
Thermal properties of food systems at high pressure (HP) are important in the design and operation of HP processing equipment. Available techniques for thermal property evaluation under HP conditions are still very limited. In this study, a dual‐needle line‐heat‐source (DNL) device was installed in an HP vessel to evaluate thermal conductivity ( k ), diffusivity (α), and volumetric heat capacity ( C pV ) of foods at high pressure. The DNL probe was calibrated using glycerin (0.1 MPa) and 2% (w/w) agar gel (0.1 to 350 MPa) at 5 and 25 °C. Calibration results showed a good correlation with the reference data of pure water: R 2 = 0.966 for thermal conductivity and R 2 = 0.837 for diffusivity, and a small standard deviation of relative error (3.18%) for the volumetric heat capacity. Fresh potato and cheddar cheese were used as test samples at 5 °C at selected pressure levels (0.1 to 350 MPa). The potato samples gave thermal properties very close to those of pure water, but much higher than those of the cheese. The k and α values of both potato and cheese increased with pressure and a 2nd‐order polynomial well fitted their pressure dependency. The volumetric heat capacity data did not show a clear pressure‐dependency trend. The experimental system worked well for the evaluation of thermal properties at pressures up to 350 MPa.