Abstract: Temperature variable resistor or thermocouples measure the temperature of the goods. The so-measured values are converted to digital temperature signals under control of a clock pulse generator at predetermined time intervals. The digital temperature signals are stored and the so-stored signals utilized to address storage locations in a permanent storage, each of the storage locations storing a weighted digital temperature signal. The weighted digital temperature signals are converted to pulse sequences and the so-formed pulse sequences summed in a summing circuit. The sum signal furnished by the summing circuit is indicative of the effectiveness of the temperature processing. Digital or analog display means may be utilized to display the sum signal and/or the individual digital temperature signals.