Swelled cans were collected over a 17-month period from outlets of two supermarket food chains. Each swelled can was classified by product and the probable cause of the swelled condition. Using weekly sales volume data for each outlet, the incidence rate of swelled cans for each type of food was estimated. The incidence rates ranged from 2.1 to 78.4 swelled cans per 100,000 units sold, depending upon the type of food. Of the 1.104 swelled cans collected, 314 (28.4%) were found to have major container defects which were assumed to have resulted in the swelled condition. Microbiological analyses were performed on the products in the remaining 790 cans; the following results were obtained: (a) typical leaker spoilage, 86%; (b) typical underprocessing spoilage, 7%; (c) thermophilic spoilage, 1% and (d) nonmicrobial swells, 6%. Using vacuum testing and double seam measurements, the causes of the leakage were determined as follows: (a) poor or questionable quality canner's end double seam, 51%; (b) leaks at locations other than the double seam, 26% and (c) poor or questionable quality manufacturer's end double seam, 4%. It was concluded that examining swelled cans of low-acid foods at the retail level is a valid method for evaluating the canning operation of commercial food processing.

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Author notes

1These studies were supported in part by FDA/PHS/HEW Contract FDA No. 223-73-2200: Minnesota Agricultural Experiment Station Scientific Journal Series Paper No. 11,474.

2Present address: Department of Food Technology and Science. P.O. Box 1071. University of Tennessee, Knoxville, TN 37901.

3Present address: Cardiac Pacemakers, Inc., 4100 Hamline Avenue, North, P.O. Box 43079. St. Paul, MN 55164.