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

6.1.3.2 Locate and clearly mark any visible defects using the Metal Can Defects, Identification and Classification Manual (8.4).

6.1.3.3 Open the cans using a sterile Bacti-disc cutter or other suitable device to cut a hole in the can manufacturer's end to approximately 5.0 cm in diameter (to accommodate the 10 ½ size Laboratory Stopper) in the centre of the container large enough to see through and remove the contents from the opening. Caution should be exercised when opening and handling contents of cans suspected of being contaminated.

Remove a portion of the product for pH, Microscopy, and Microbiological Analysis.

6.1.3.4 Examine the contents for off-odours or other evidence of spoilage, e.g., frothing, curdling, discolouration, etc., immediately after opening the container, and before emptying contents.

6.1.3.5 Remove the contents and rinse the emptied container in running warm water to remove adhering product.

Place the unwanted contents in a suitable container for sterilization prior to disposing. (swollen or suspect cans only).

6.1.3.6 To clean, immerse the container in a warm (40-45°C) 5% Extran 300 detergent solution (or other suitable grease/fat removing household dish washing detergent) for at least 30 minutes. Use a soft brush to assist cleaning. Clean the container throughly by rinsing in warm running tap water.

6.1.3.7 Dry the container at 35°C overnight. After drying, allow the container to cool to room temperature.

6.1.4 Normal cans (non-swollen)

Before piercing the container, ensure that the surface is disinfected with undiluted Ethanol and dried completely before opening.

Open the cans using a sterile Bacti-disc cutter or other suitable device to cut a hole in the can manufacturer's end to approximately 5.0 cm in diameter (to accommodate the 10½ size Laboratory Stopper) in the centre of the container large enough to see through, and remove the contents from the opening and to facilitate the micro-leak vacuum/pressure test.

Remove a portion of the product for other analyses and sterilization of the discarded product is not required.

Swollen cans

Place the container in a shallow tray containing sufficient quantity of the buffered chlorine solution, or its equivalent, to receive any material which may drip from the funnel after the can is opened.

Invert the funnel and cover the end of the can to be opened. Insert the steel rod and while holding the funnel (funnel device see Appendix A) firmly in place over the container end give the steel rod a sharp blow sufficient to pierce the end of the container. Do not remove the funnel until all frothing, spraying, etc., has ceased.

Alternatively place the container in a sterile plastic bag and while holding the open end of the bag firmly about the Bacti-disc opener shaft pierce the container. Do not remove the container until it has completely vented. This method has in practice proven to be the best for swollen flexible pouch products. Open the can to approximately 5.0 cm in diameter and remove a portion of the product for other analyses.
Place the contents in a suitable container for sterilization prior to discarding.

6.1.5 Glass container with metal lids - Check for any problems and proceed to visual inspection.

6.2 Container examination and evaluation procedure

This procedure applies to all metal cans and glass containers with metal lids. The purpose of the following sections is to provide a complete evaluation of metal and glass container. The optional tests are for additional information if required.

6.2.1 Visual inspection and assessment of container

Place the container (can or glass) on one hand and rotate the container using the other hand to visually determine the presence of defects around the container. On metal containers use the thumb and the forefinger of the other hand to examine both can ends and record all defects. An image analysis computer at 25X magnification generates more desired results without the possible injury to one's fingers. Run the fiber optic lens attachment around the perimeter of the double seam and then along the side seam. A serious fault should be digitized and saved to the computer for future consideration. Exercise caution because metal can ends may have sharp edges. Ensure that the can body and the side seam are also examined for possible defects.

Always indicate the area in which the defects are observed i.e. can body, side seam and the double seam ends which correspond to either the can manufacturer or to the canner's end.

For glass containers examine the glass enclosure, and the cap (lid) using the classification of glass container defects in the Meat and Hygiene Manual Procedures ,15.4.3.8.3.2 (8.2).

6.2.2 External measurement of containers

Metal container - seam measurements include the counter sink measurement, seam thickness and seam length. These measurements are deemed necessary in special investigational situations.

Glass container - cap tilt, cap security, lug position, cap removal torque optional due to the destructive nature of this test.

6.2.3 Measurement of Bourdon Vacuum and Net Headspace Volume (MFHPB-04) Follow the procedure as outlined in this method. These parameters are required in special investigational situations only and must be performed before the container is opened for other analyses.

6.2.4 Measurement of pH (MFHPB-03). Follow the procedure as outlined in the method.

6.2.5 Determination of Micro-Leaks using Pressure/Vacuum Tests (MFHPB-05). Follow the procedure as outlined in the method.

6.2.6 Double Seam tear-down of metal container

6.2.6.1 Preparation of a cross-section

The coded end or the food processor's end should be emphasised in double seam evaluations. The food processor's seams are usually more inferior in quality than the can manufacturer's seams. Use the electric can opener to remove the end plate as close as possible to the double seam. See diagram