A novel instrument for rapid measurement of temperature-dependent thermal properties of conduction-heated food up to 140 °C

• A novel instrument to measure temperature-dependent thermal conductivity at elevated temperatures.
• Measurement time is less than 1 min as compared to 5–6 h using other methods.
• Accurate at elevated temperatures, such as aseptic hold tube temperatures.
• Instrument design is based on sensitivity analysis.
• Accurate thermal properties can be used for enhanced food safety and quality.

Estimating thermal properties for thick or solid foods at temperatures greater than 100 °C is challenging for two reasons: the long time needed to reach a constant temperature, and the pressure needed to be maintained in the sealed container. An instrument (“Thermal Properties Cell”, or “TPCell”) was developed based on a rapid non-isothermal method to estimate the temperature-dependent thermal properties within a range of commercial food processes (20–140 °C). The instrument design consists of a custom sample holder and special fittings to accommodate the heater within a pressurized environment. The total time of the experiment is less than 1min., compared to existing isothermal instruments requiring 5–6 h to cover a similar temperature range. Thermal conductivities of different food materials were estimated for the temperature range of commercial food processes. The novelty of the instrument lies in its ability to analyze transient temperature data using a nonlinear form of the two-dimensional heat conduction equations.