M-I-01-5: Concerns with Tetra Pak's Vacuum Thermal Instant Sterilizer (VTIS) Higher Heat Shorter Time (HHST) Pasteurizer and Aseptic Processing System Vacuum Chambers
200 C Street, SW
Washington DC 20204
December 31, 2001
TO: All Regional Food and Drug Directors
Attn: Regional Milk Specialists
FROM: Milk Safety Branch (HFS-626)
SUBJECT: Concerns with Tetra Pak's Vacuum Thermal Instant Sterilizer (VTIS) Higher Heat Shorter Time (HHST) Pasteurizer and Aseptic Processing System Vacuum Chambers
Problems regarding the construction and cleaning of this equipment have been observed in the field. This memorandum explains the concerns, provides Tetra Pak's response to these concerns and suggests possible regulatory follow-up actions.
The vacuum chambers in question are a part of Tetra Pak's VTIS HHST and aseptic steam injection milk and milk product processing systems. The purpose of the vacuum chamber is to remove the water, added during steam injection, and to provide the initial cooling of product leaving the holding tube.
These systems have been in use for over twelve (12) years in the United States. Currently these systems are in operation in approximately twenty-two (22) milk-processing plants across the U.S.
During the past year, FDA Regional Milk Specialists have observed serious construction and cleaning problems associated with these vacuum chambers.
While investigating these problems, the Milk Safety Team (MST) has learned that an older design, sold from 1989 to sometime in 1998, is likely to have construction problems. These construction problems generally include internal welds that are not completely joined in the product contact area. These problem welds are in the product inlet and distribution passages, located along the inner wall of the chamber. The welds in the product inlet passage and in the first part of the product distribution passage can only be seen by using a scope inserted into the product inlet passage. When it is possible to remove the outer cover or bell, the welds in the last section of the product distribution passage can also be evaluated using a scope inserted into the outlet of this passage. While the welds in post 1998 vacuum chambers are more likely to be satisfactory for the intended use, all of these chambers should be examined.
Cleaning of this equipment has also raised concern. Minor deviations from the manufacturer's cleaning recommendations can result in thick layers of product build up on product contact surfaces. Serious cleaning problems in the product inlet and distribution passages have been observed in both the pre- and post 1998 designs.
Tetra Pak's Response
Tetra Pak has begun using a scope to view and videotape the condition and cleanliness of the product inlet and distribution passages of every VTIS vacuum chamber installed in a milk plant in the U. S. They plan to have all of them examined and video taped by May 2002. State regulators and FDA Regional Milk Specialists have been and will be notified when they will perform these examinations.
All equipment found needing repairs will be repaired and re-examined.
The cleaning regimens of all equipment found soiled will be re-evaluated and modified as needed. The equipment will be re-examined at approximately weekly intervals until it is found clean or is removed from service.
Examination of these chambers will continue on a periodic basis for as long as this equipment remains in use. The examination frequency for clean equipment that does not need repair, or has been adequately repaired, will be approximately each six (6) months to start. If the Regulatory Agency agrees, this frequency may be extended as long as the equipment is found clean at each examination. If it is found soiled, the cleaning regimen will be re-evaluated and modified as needed. The equipment will be re-examined at approximately weekly intervals until it is found clean or is removed from service.
Suggested Regulatory Follow-up
MST suggests that State regulators and, when possible, FDA Regional Milk Specialists, accompany the Tetra Pak technicians when they examine and video tape the vacuum chambers. MST has noted that despite efforts to "stiffen" the scope, it can fall from the viewing position where the upper portions of the distribution passages can be observed. It is these upper areas that are most likely to be soiled. Simply viewing the video, after the fact, can be confusing. If the scope falls to the bottom, it can in some cases, look a lot like the top. The outer cover or bell should be removed, if possible, and the distribution passages examined from the outlet end of this passage.
While MST recognizes that Regulatory Agencies have the right to deal with these concerns in whatever manner they choose, we suggest that if the vacuum chamber is examined, repaired and monitored as described above and is consistently clean when periodically examined, that this existing equipment continues to meet the requirements of the Grade "A" PMO.
MST has been informed that Tetra Pak, Inc. is redesigning the vacuum chamber to make all surfaces visible for inspection and make it easier to clean.
We suggest that all new installations be of the new design when it becomes available.
Copies of this memorandum are enclosed for distribution to Regional Milk Specialists, State Milk Regulatory Agencies and State Milk Sanitation Rating Officers in your region. This memorandum will also be available on the FDA Web site at http://www.cfsan.fda.gov at a later date and should be widely distributed to representatives of the dairy industry and other interested parties.
Robert F. Hennes, RS, MPH
Chief, Milk Safety Team