ISSN:
1365-2621
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Freezing time, weight loss and power demand can be calculated by equations in which the enthalpy gradient, namely, the specific heat requires to be expressed as a temperature function. Since the temperature at which freezing starts varies with the material of the food and its water content, the author has established equations for the freezing point tf of beef, pork, lamb and fish and its variation with their water contents. That temperature serves as the reference point θ= -t+tf= 0 of a unified temperature scale with enthalpy H= 0. The change of enthalpy in the freezing range can be divided into two sections. The first one, which covers the band from θ= 0 to θg= 6, is characterized by a steep enthalpy gradient which can be expressed by a linear change of the ratio θ/H with the temperature θ. The second section covers the range θ 〉 θg and is characterized by a small enthalpy gradient with the resulting functions H= Cθn and c=n(H/θ). The author has established equations for the numerical values of n and C for various meats and fish depending on their water contents and has produced diagrams of the specific heat in the low temperature range.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2621.1979.tb00901.x
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