Measuring the temperature of foods is used to determine safety and degree of doneness. Thus, the mesasurement of temperature is important. Generally, food temperature is measured in the center of the product. However, there are some exceptions, such as in commercial processing. For example, in canned foods it has been found that the most accurate temperature curve and history are found by measuring just out from the center of the product in the can or jar.

Once the temperature recording device is positioned, it is fairly easy to record the temperature. However, if a thermometer contains a liquid (mercury or alcohol), it is important to always record the measurement by viewingg the meniscus at eye level.

Consider the thermocoupler inserted in the steak above. A variety of factors affect the accuracy of the recording, including the thickness of the coupled wires, and the accuracy with which the thermocoupler marks the dot on the recording paper. Reliability of using a thermocoupler is only to nearest degrees, rather than tenths.

Today, many temperature recording devices are attached to computers, thereby reducing the amount of actual work in studying things such as thermal properties, and the risk of human error.

Above we see a number of temperature measuring devices. The large box on the right is a recorder which interprets temperature from thermocouples. Thermocouples are made of copper and constantan. The copper-constantan thermocouples are joined at the point where temperature is recorded. The different types of metal expand differently, setting up a voltage difference that travels along the wire to the recorderfor interpretation. There are a number of other measuring devices, including a mercury thermometer which relies on the expansion of mercury to record the temperature, and an alcohol thermometer which does the same.

Time-Temperature Indicators change color as a function of both time and cumulative temperature exposure. The faster a chemical reaction, the faster the temperature change and the faster the color change. Time-temperature indicators can be used to both look at increased temperature during cooking and as a storage indicator for freezer and refrigeration storage.