What tool is commonly used to measure food temperature?

A thermometer is commonly used to measure food temperature because it provides accurate readings of the internal temperature of food items. This is crucial in culinary practices to ensure that food is cooked to safe temperatures, which helps prevent foodborne illnesses. Thermometers come in various types, such as digital, instant-read, and probe thermometers, each designed to give quick and reliable temperature readings.

The other tools listed serve different purposes. A hydrometer measures the specific gravity of liquids, which is not relevant to temperature measurement in cooking. A barometer is used to measure atmospheric pressure, and while this might affect certain cooking processes (like baking), it does not measure food temperature. A calorimeter is a device used to measure the heat transfer in various processes, often in chemical reactions, but it is not typically employed in the kitchen for temperature readings. Thus, the thermometer stands out as the essential tool for measuring food temperature.