Guide to Inspections of Low Acid Canned Food 41
Manufacturers - 2
in the late 1960's and early 1970's. Due to problems encountered with flame sterilization in that industry there are currently no known flame sterilizers in use in the United States for lacf.
Flame sterilization is basically a high-temperature, short-time process, where cans of convection heated product closed under a high vacuum, are first preheated with steam to 212° F and then heated by direct contact with gas flames at 2,000° F, while rotating rapidly. Because of internal pressures generated during processing the process is limited to small size cans. This is normally done by rolling the cans while conveying them through the processing stages. In effect the can itself becomes the processing vessel. After being heated to processing temperature, the cans pass through a holding section prior to being cooled. After processing the can rolls through a series of water sprays to cool the container. If the can is heated to too high a temperature the container ends are distorted and the can may burst. If the container vacuum is not controlled the container ends may burst or become stressed during processing. If the container is not exposed to the open flame for the required amount of time the processing temperature in the can will not be reached and the can may be severely underprocessed. For this reason container conveyor speed is very important to achieving the filed scheduled process in this system.
Initial temperature is critical to the thermal process received in the flame sterilizer. A change of only 1° F in the initial temperature can significantly change the lethality received by the product. Initial temperature is determined by measuring the outside temperature of the container with a pyrometer prior to the container entering the flame sterilization section. The outside temperature of the containers is reported to be the same as the cold spot of the container because of the rapid heating of the product at this point in production.
If properly operated the flame sterilization method is claimed to produce a high quality product using a very short processing time. For a 4 oz can of mushrooms a processing time of only 12 minutes is needed including the cooling time.
Due to the problems noted above the flame sterilizer is no longer used in most of the world, however an interest in flame processing is still expressed at times in current food processing literature.
THERMAL PROCESSING RECORDS
21CFR 113.100 (a) addresses record keeping requirements for all processing systems. Information that must be contained on all batch records include product, code number, date, retort or processing system number, size of container, approximate number of containers per coding interval, initial temperature, actual processing time, mercury-in-glass and recording thermometer readings, and other appropriate processing data. Closing machine vacuum in vacuum packed products, maximum fill-in or drained weight, or other critical factors specified in the scheduled process must also be recorded.
Additional record keeping requirements for specific processing systems, including: still retorts, agitating retorts, hydrostatic retorts, aseptic processing and packaging systems, flame sterilizers, food preservation methods where critical factors (such as water activity) are used in conjunction with thermal processing, and other systems are contained in 113.100(a) 1-7.
Other processing systems were developed after the regulations were published including the cascading water, the spray water, and the steam- air retort. In addition to the record keeping requirements of 113.100(a), additional record keeping requirements for these systems include:
cascading water retort: water flow rate; time and temperature at each come up step.
spray water retort: water flow rate; time and temperature at each come up step.
steam-air retort: fan rpm's and maximum over pressure. Pressure readings should not deviate from the filed over pressure.
21 CFR 113.100 (b) covers requirements for recording charts and record review. Recording thermometer charts must be identified by date, retort number, and other data as necessary, so they can be correlated with the written record of lots processed. 21 CFR 113.100(c) addresses written records for container closure examination. It requires written records of all container closure examinations to specify product code, date and time of container closure inspections, measurements obtained, and all corrective actions taken. Records must be signed or initialed by the container closure inspector and reviewed by management with sufficient frequency to ensure that the containers are hermetically sealed. As a practical matter, most firm's review records within 1 working day of the process, although this is not required. Specific examinations required by the regulations are contained in 21 CFR 113.60.
All processing and production information is required to be entered at the time it is observed by the retort operator, processing system operator, or other designated person at the time the specific retort or processing system condition or operation occurs; and this retort or processing system operator or other designated person must sign or initial each record form.