84 Meat refrigeration 14.1 Instrumentation The first consideration is the range of temperatures to be measured. For the meat industry, a range from -40 to +150C would cope with the tempera tures found in freezers, chillers, storage rooms, retail display cabinets and in water used for cleaning or scalding tanks in the abattoir. If they produce cooked meat products then the upper temperature may rise to 250-300C. As well as the measuring range, the range of ambient temperatures over hich the instrument will work needs to be considered The electronics of many temperature measurement instruments are designed to work to the pecified accuracy only within certain ambient temperature ranges, usually 0-40C. If temperatures in a cold store are to be measured the instrument itself may need to be kept warm until it is used. 14.1.1 Hand-held digital thermometers Purely from a cost consideration many small producers and retailers rely on spot temperature checks obtained using hand-held thermometers to produce the temperature records they require. The main tasks they carry ut with such equipment is the measurement of air temperature, between pack or product temperature, and the temperature of the meat itself. They require thermometers that are accurate, easy to use, react quickly and ar robust. Ease of use is a personal judgement and best answered by trying out a range of instruments. Most modern electronic thermometers are reli- able if handled with reasonable care. However, in general, the more robust the sensor the slower the response. There are three types of digital thermometer generally available: ther- mocouple, platinum resistance or semi-conductor(thermistor). The name refers to the type of temperature sensor used. Type T(copper-constantan) thermocouple thermometers with a wide range of interchangeable sensors are the most widely used because of their wide temperature range and rea- sonable accuracy. The accuracy of the temperature measurement of a digita thermometer will depend on how accurate the instrument and the sensor It can be seen from Table 14.1 that only thermometers based on ther mistor or platinum resistance sensors can be guaranteed to provide better than +0.5C accuracy. However, it is possible to calibrate any thermometer at known temperatures and use the calibration curve obtained to correct errors in measured values. In many cases the supplier of the instru- ment can provide a calibration curve for a particular instrument/sensor combination Sensors do not immediately in which they are positioned. Their ure the temperature of the meat or air onse rate depends on the sensor itself and the environment in which it is used. a thin sensor in a wet/solid food will respond rapidly, and a thick sensor in still air very slowly. When14.1 Instrumentation The first consideration is the range of temperatures to be measured. For the meat industry, a range from -40 to +150 °C would cope with the tempera￾tures found in freezers, chillers, storage rooms, retail display cabinets and in water used for cleaning or scalding tanks in the abattoir. If they produce cooked meat products then the upper temperature may rise to 250–300 °C. As well as the measuring range, the range of ambient temperatures over which the instrument will work needs to be considered. The electronics of many temperature measurement instruments are designed to work to the specified accuracy only within certain ambient temperature ranges, usually 0–40 °C. If temperatures in a cold store are to be measured the instrument itself may need to be kept warm until it is used. 14.1.1 Hand-held digital thermometers Purely from a cost consideration many small producers and retailers rely on spot temperature checks obtained using hand-held thermometers to produce the temperature records they require. The main tasks they carry out with such equipment is the measurement of air temperature, between pack or product temperature, and the temperature of the meat itself. They require thermometers that are accurate, easy to use, react quickly and are robust. Ease of use is a personal judgement and best answered by trying out a range of instruments. Most modern electronic thermometers are reli￾able if handled with reasonable care. However, in general, the more robust the sensor the slower the response. There are three types of digital thermometer generally available: ther￾mocouple, platinum resistance or semi-conductor (thermistor). The name refers to the type of temperature sensor used. Type T (copper–constantan) thermocouple thermometers with a wide range of interchangeable sensors are the most widely used because of their wide temperature range and rea￾sonable accuracy.The accuracy of the temperature measurement of a digital thermometer will depend on how accurate the instrument and the sensor are. It can be seen from Table 14.1 that only thermometers based on ther￾mistor or platinum resistance sensors can be guaranteed to provide better than ±0.5 °C accuracy. However, it is possible to calibrate any thermometer at known temperatures and use the calibration curve obtained to correct errors in measured values. In many cases the supplier of the instru￾ment can provide a calibration curve for a particular instrument/sensor combination. Sensors do not immediately measure the temperature of the meat or air in which they are positioned. Their response rate depends on the sensor itself and the environment in which it is used. A thin sensor in a wet/solid food will respond rapidly, and a thick sensor in still air very slowly. When 284 Meat refrigeration