Guide to Inspections of Low Acid Canned Food 23
Manufacturers - 2
inoculated pack method is to determine the time/temperature combination that will kill all of the spores added to the product. A similar method called the count reduction method uses a procedure which relates the decrease in the numbers of spores from the initial number to some final number with process Fº value. Processes may also be established using other procedures such as chemical indicators to provide Fº values.
The process should be established by qualified persons having expert knowledge of the thermal processing requirements of lacf, and having adequate equipment and facilities to make such determinations. All critical factors, including the establishment of venting or other come-up procedures to ensure adequate temperature distribution, must be investigated by the processing authority. There must be some form of documentation on hand at the factory; at least a letter or other similar transmittal from the processing authority, which details all factors critical to the delivery of the scheduled process.
Should no documentation exist at the plant, every effort should be made to determine whether such documentation exists at any location, before leaving the plant.
Should the documentation for the scheduled thermal process be more extensive than a letter or other similar document, a preliminary review should be made to determine if any of the procedures are questionable (it may not always be possible to accomplish this at foreign plants if the documentation is not in English). If the documentation is questionable, or if it is not in English, copies should be collected for review by the Center for Food Safety and Applied Nutrition (CFSAN).
The information from the processing authority should be compared with the operations at the firm and with the information which the firm submitted with their filed scheduled thermal process. Possible problem areas in the documentation should be noted for CFSAN review. See Part One of this guide -Guide to lacf Manufacturers, Administrative Procedures\Scheduled Processes, for additional information on process establishment, including inspectional considerations and process deviations.
The lacf regulations CFR 21 Part 113.40 require that crates, trays, gondolas etc. for holding containers must be made of strap iron, adequately perforated sheet metal or other suitable material. When perforated sheet metal is used for the bottoms, the perforations should be approximately the equivalent of 1 inch holes on 2 inch centers. If divider plates are used they should be perforated as above.
Other arrangements can be used as long as there is temperature distribution documentation on hand for the equipment in use. It is important for good temperature distribution to use a crate with as much open area as possible. The percent open area of the crate bottom and the divider plate can be calculated by dividing the total open area of the holes by the total area of the bottom or divider plate x 100. A divider plate which meets the specification of the regulations (1 inch holes on 2 inch centers) has approximately 27% open space. Tightly packed small round containers may cover over 90% of the divider plate. The holes in divider plates must be carefully designed to provide for the maximum heating medium flow between the containers. By using closely spaced smaller holes the percent open space can be dramatically increased. The crates and divider plates in use should at least be no more restrictive than those used to establish the retort operating procedures. When a firm changes the type or design of divider plates the effect of the new divider plates must be evaluated by the firms processing authority.
If dividers, racks, trays, or other means are used to position flexible containers in place they must be designed and employed to ensure even circulation of the heating medium around all containers.
Equipment and procedures common to all retort systems has been previously discussed. The following sections will discuss equipment and procedures as they apply to each of the various types of retort systems. In addition to the common types of retort systems discussed there are other less common types which may be encountered.
When inspecting these systems always review the referenced CFR sections to determine compliance of equipment installation and operation.
STILL STEAM RETORTS
Equipment and procedures for pressure processing in steam in still retorts are covered by 21CFR 113.40(a) of the lacf regulations.
Still steam retorts (Attachment 4) are identified as vertical, in which the crates are lowered by hand or overhead hoist into the retort; horizontal, in which the crates are pushed or conveyed into the retort; or crateless (Attachment 5), in which the containers drop into cushion water in the retort. Vertical retorts vary from small one crate, to retorts holding several