Acquisition, storage, and review of safety data from a commercial system for high temperature, short time...

A high temperature, short time (HTST) pasteurization system was equipped with electronic sensors to determine the temperature, pressure, flow rate, and position of the flow diversion valve. A computer for data acquisition was wired to the sensors to monitor and to record processing conditions related to public health. The processing conditions were stored in safety files on the hard drive of the computer, transferred weekly to a tape drive, and stored. The processing conditions of the HTST system were monitored for 270 d to determine the accuracy and reliability of the data acquisition system. The size of the HTST safety files ranged from 6.2 to 9.1 MB when the sensors were monitored every second. The file size was reduced to < 1.8 MB when the monitoring frequency was increased to every 5 s. To determine accuracy, the temperatures recorded by the data acquisition system were compared with the temperatures recorded by an electronic recorder controller. To determine reliability, changes in the position of the flow diversion valve were examined to identify process deviations and were compared with the event marker on circular charts. The review of the data file by the actual time method was an effective alternative to the electronic recorder controller for monitoring the completeness of data in the safety files. Off-line review to determine reliability required approximately 10 min/d of records.