Ultrasonic monitoring of unsteady-state cooling of food products

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The cooling (50°C to 2°C) of blocks of gelatin, chicken, salmon, beef, and yogurt was monitored using ultrasonic time of flight (TOF) measurements. Heat loss was from one side and the core temperature was monitored with a thermocouple and modeled as unsteady-state heat transfer in an infinite slab. The TOF of an ultrasonic (2.25 MHz) pulse parallel to the direction of heat loss was measured simultaneously. The ultrasonic TOF increased at a decreasing rate during the cooling process, reaching a constant value when the rate of change of temperature with time was zero. The ultrasonic TOF measurement showed good agreement with a theoretical prediction of both TOF and core temperature based on a time integral of speed of sound calculated as a function of time and position. Ultrasonics offers a non-invasive means to monitor product temperature online during a cooling process.

Original languageEnglish (US)
Pages (from-to)1235-1240
Number of pages6
JournalTransactions of the American Society of Agricultural Engineers
Issue number5
StatePublished - Dec 1 2001

All Science Journal Classification (ASJC) codes

  • Agricultural and Biological Sciences (miscellaneous)


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