Method for Examination and Evaluation of Hermetically Sealed Metal Cans and Glass Container

MFHPB-06
February 2003

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Dev C. Nundy
Food Laboratory,
Ottawa Laboratory (Carling)
Canadian Food Inspection Agency
Ottawa, Ontario, K1A 0C6

E-mail: dnundy@inspection.gc.ca

Alexander Fabricius
Fish/Food Laboratory
Canadian Food Inspection Agency
Mississauga, Ontario, L5T 2R4

E-mail: fabriciusa@inspection.gc.ca

1. APPLICATION

This method is designed to detect defects, that may adversely affect the hermetic seal. It is applicable to all two and three piece metal cans having a conventional doubleseam and glass container with metal cap (lids) used for products which require sterilization. It provides both qualitative and quantitative information on the assessment of the double seam on metal cans and defects in glass enclosure. This method should be used in conjunction with the Metal Can Defects, Identification and Classification Manual (9.1). This revised method replaces MFHPB-25F, dated October 1991.

2. PRINCIPLE

The method describes the physical separation (tear-down) of the components of doubleseams and tests for identifying defects in metal cans and glass containers to assess certain criteria essential to the formation of a hermetic seal. It also provides an evaluation of can and glass container defects according to their severity which may result in loss or potential loss of container integrity (hermeticity).

Published on the Food Directorate's (Health Canada's) website at http://www.hc-sc.gc.ca/food-aliment.

3. DEFINITION OF TERMS

See Appendix A of Volume 2.

4. COLLECTION OF SAMPLES

See Appendix B of Volume 2.

5. MATERIALS AND SPECIAL EQUIPMENT

1. Bacti-Disc Cutters (Wilkens-Anderson Co., Dixie Canner Equipment Co.)
2. Metal nipper
3. Double blade mechanical saw
4. Torque meter (Optional)
5. Emery paper
6. Seam micrometer (.001 of an inch)
7. Seam projector or Computer with an image analysis software.
8. Safety gloves for sharp objects
9. Safety eye protection
10. Hearing protection
11. Electric Can Opener
12. Laminar Hood
13. Biohazard Hood
14. Ethanol
15. Fiberglass Eraser

6. PROCEDURE

6.1 Handling and preparation of the sample unit

Use the proper procedure and preparation when handling any swollen containers since there is a possibility that Clostridium botulinum and or their toxins may be present. Use of safety gloves for sharp objects, safety eye glasses and appropriate hearing protection is mandatory for cutting metal and handling cut metal pieces.

6.1.1 Removal and identification of the label

Place two coincident marks on the label and the can about 120/ apart. The marks on the can should be made with indelible ink, carborundum or diamond pencil so that they will not be removed during subsequent handling of the container. These marks will permit establishment of the position of the label on the can after its removal. A visual identification (inspection) of sample unit (container) must be performed after removal of label from the can. Store the label for future reference. (Only Necessary When Conducting Special Investigations). Otherwise Note any unusual liquid stains and sharp object perforations, if none present, remove the label and place an identification mark on the can.

6.1.2 Identification of sample unit

Legibly identify each sample unit directly on the can. This must be done in a manner so that the identity is not lost or removed during subsequent handling and testing. Ensure that the identity relates to the sample from which each sample unit is derived. The complete code shall be recorded for each sample unit.

6.1.3 Cleaning preparation of external and internal container surface

6.1.3.1 Clean any adhering food, dirt and soil from the surface of the can to be opened.

If the container is very dirty, scrubbing with detergent and water may be necessary. Alternatively soak can in warm water with detergent for ½hr, then rinse in hot water and clean with bottle brush to remove food residue if present and throughly rinse with hot water and drain to let it dry. Place the cans in either the Laminar or Biohazard Hood. Disinfect the surface with undiluted Ethanol prior to opening. Let it dry.