A sensor, or instrument , is a device for measuring the magnitude of a physical variable. Sensors play an important role in the food industry. They are required to provide raw data to process monitor and control systems. Sensors can be contacting or noncontacing devices. The automation of food processing requires reliable sensors for the measurement of process variable such as pressure, temperature, flow, moisture ,color, and viscosity. Sensors are also needed in food manufacturing for securing food quality and safety, and in meeting productivity and environmental/energy concerns. In-line sensors help to produce more consistent food products while increasing productivity and decreasing production costs. Due to their diversity, food manufacturing facilities require various sensors for detection and measurements. Sensors are the eyes and ears of the manufacturing processes. Thus these are the interface modules between the physical world and computers.