Advantages and Characteristics of Digital Food Thermometers
In most regards a digital thermometer offers the same functions as a traditional thermometer.
Imagine food preparation without a thermometer? There would be no safe and effective way of measuring whether food is properly cooked by visual means alone.
Whether the fault of the operator or of the equipment being used, it is possible to under prepare or over prepare food. A faulty oven or grill, a miscalculation in terms of the time needed to cook could all result in spoiled or dangerous food.
The only absolute way to be sure that food has been prepared properly is by using a thermometer.
Advantages of a Digital Thermometer
Digital thermometers tend to be easily portable and are highly accurate.
They will either have a probe attached or a built in probe that is placed onto or into the product being tested and a digital display giving a highly accurate temperature reading.
The temperature measuring tip of a digital thermometer us usually one of three slightly different variants;
Thermocouples use two different metals that have a different co-efficient of expansion when heated. This expansive response to heat is predictable and the current that passes between the two dissimilar tips can be measured and given to the user of a digital thermometer on a display.
Various metals are used depending on the use case and temperature variance of the substance being measured. Nickel, tungsten, copper and platinum as well as other metals might all be appropriate depending on the range of temperatures expected.
A thermistor is a single metal device where the resistance varies reliably according to temperature. Measuring the received current in comparison to the transmitted current allows accurate temperature readings to be taken.
Digital thermometers that use thermistors are most commonly built around the principle of NTC; negative temperature coefficient. NTC is where the resistance of a substance decreases as it heats up. The other, rarely used alternative is PTC which, unsurprisingly, stands for positive temperature coefficient which is where resistance increases with temperature.
A typical digital thermometer using NTC principle will have oxides of nickel, copper or iron elements.
They are highly reliable, can be made very compact and portable. The only downside is their lack of utility in extreme temperatures.
Resistance Temperature Detection
Resistance temperature detection relies on measuring the number of Ohms through a variably resistant coil or membrane. The conductive nature of the material varies reliably in relation to its heat. Comark uses highly sensitive Pt100 sensors.
In other words the hotter the material, the less resistant it is and the more current is allowed to pass through it without being converted to heat or friction itself.
Importantly this is a very reliable and predictable scale. Calibrated correctly a digital thermometer is capable of accuracy to better than one hundredth of a degree Celsius.
Slightly more exotic materials make the best detectors with platinum being favoured both due to the reliability of its behaviour and the speed at which it responds to temperature changes making the digital thermometer very fast to respond in use.
Copper and nickel can also be used if correctly protected from oxidisation though they do not have the extreme range of predictable use that platinum does.
The feature sets and use cases of all three types makes these three types of digital thermometer makes them all highly suitable for food preparation and food storage.
All thermometers should be calibrated frequently. The Ice Calibration Method using a crushed ice solution can be used to check the accuracy of your thermometer.
Read more about food thermometers here and here.