Real-time wireless temperature measurement during high pressure processing
- How does it work?
- What can it be used for?
- What can it not be used for?
- Related Facilities
- Further Information
|Key words||high pressure treatment, process control, real-time temperature monitoring, compression heating|
How does it work?
|Primary objective||To control high pressure processing by transmitting real time temperature data using a wireless transmission system.|
|Working principle|| Preserving food with pressure is a gentle method to kill germs and bacteria (,,). Structure, vitamins and micronutrients suffer little change when sticking to specific process parameters (,). During high pressure processing, a temperature increase of the pressurized material occurs (e.g. 3°C/100 MPa for high water content foods ). To avoid or minimize over-processing, an online process–control device is necessary (,).
This tool collects data inside the high-pressure vessel and transmits them for further processing to a PC or other evaluation units outside the high-pressure-chamber.
The principle of this technology is based on the measurement of temperature inside the high pressure vessel using a wired thermal resistor as probe to change the frequency of a Voltage Controlled Oscillator (VCO).
The thermal resistor is very small (Ø1.5 x 1 mm with isolation, operating range 55°C 150°C), so it has little effect on the measured product, also the reaction time to temperature changes is very short. It is connected to a capsule (Ø85 x 180mm) which contains an electronic power device (battery operating time 5:30h) and ultrasonic transmission system. To measure one probe a bandwidth of 5 – 10 kHz is needed. The operating frequency for data transmission is selectable from 16 kHz to 80 kHz depending on the structure-borne noise of the high-pressure system. A sensitive microphone on the outside of the vessel records the frequencies transmitted by the capsule. With a Fast Fourier Transformation, a computer immediately does the backward translation into temperature-related data and could be used to control the preserving process. Due to its analogue method of operation, the resolution of the device is very fine (± 0.1°C). The measurement range is tested in temperatures from 0 80°C and within 0.1 to 600 MPa (conditions currently used in food processing by high pressure).
It is possible to connect further probes (temperature, pressure or in development pH-value) to the capsule to get additional data from inside the vessel. For each transmission 5-10kHz bandwidth is needed.
The capsule is placed within the chamber or in the handling basket. The wired thermal resistor is placed in contact with the packed foods to measure.
Due to the working principle, each probe has to be calibrated first, before it is used at high pressure.
|Additional effects|| Higher treatment capacity and productivity of the high pressure equipment as a result of:
|Important process parameters|| Operating frequency for data-transmission: 16 to 80kHz
Lowest measurable temperature: 0°C Highest measurable temperature: 80°C Pressure range: 0.1-600MPa Battery operating time: 5:30 h (up to 500 charge-cycles) Environment: no restriction inside a high pressure vessel
|Important product parameters||-|
What can it be used for?
|Products||For all kind of products for which temperature in a high pressure vessel should be measured (e.g. Meat, fish, vegetable and fruit products).|
|Operations||Temperature measurement, real-time process control, pasteurisation, structure forming|
|Solutions for short comings||
What can it NOT be used for?
|Operations||High pressure thermal sterilisation High Pressure sterilisation|
|Risks or hazards||Depending on the number of probes, temperature non-uniformity might be not detected|
|Maturity||Prototype available for high pressure vessels (industry machines)|
|Modularity /Implementation||Extendible to additional sensors (pressure, pH)|
|Consumer aspects||Easy to use|
|Environmental aspects||Optimizing production processes, energy saving ()|
Facilities that might be interesting for you
|Institutes||DIL, University of Erlangen-Nürnberg|
|References||  Knorr, D. (1999). Novel approaches in food-processing technology: new technologies for preserving foods and modifying function. Current Opinions in Biotechnology 10: 485-491.
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 Heremans, K. (1982). High pressure effects on proteins and other biomolecules. Annual Review of Biophysics and Bioengineering 11: 1-21.
 Heremans, K. (1995). High pressure effects on biomolecules. High Pressure Processing of Foods. D. A. Ledward, D. E. Johnston, R. G. Earnshaw and A. P. M. Hasting. Nottingham, Nottingham University Press.
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Operating frequency for data-transmission: 16 to 80kHz Lowest measurable temperature: 0°C Highest measurable temperature: 80°C Pressure range: 0.1-600MPa Battery operating time: 5:30 h (up to 500 charge-cycles) Environment: no restriction inside a high pressure vesselwarning.png"Operating frequency for data-transmission: 16 to 80kHz Lowest measurable temperature: 0°C Highest measurable temperature: 80°C Pressure range: 0.1-600MPa Battery operating time: 5:30 h (up to 500 charge-cycles) Environment: no restriction inside a high pressure vessel" cannot be used as a page name in this wiki. - Sensors and Indicators 2.1.1 physical other ICT Science Direct, Web of science Search terms: High Pressure Treatment, compression heating, temperature WikiSysop :Template:Review document :Template:Review status