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Public Health Safety of Low-Acid Canned Foods (LACFs) in Pressurized Metal Containers


The objective of this project was to provide recommendations that would preclude the erosion of public health safety associated with vacuum-packed cans, should underprocessing of a LACF in a pressurized can occur.

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FDA has questioned the safety factors involved when low acid foods are canned and stored in containers pressurized with an inert atmosphere of nitrogen. Application of this packaging technology for low-acid foods would greatly complicate the possibility of finding swelled containers as the usual warning sign of botulism. The variability of liquid nitrogen injections may produce a highly varied pressure background. This would make detection of a swollen can difficult to detect even with instrumental methods. The possibility of detecting gas production in pressurized cans by appropriate sensitive instruments such as that available from Ellab was evaluated for its effectiveness and sensitivity. Data collected up to the present suggests it is possible to detect a deflection difference 1 bar above background. Increased pressure due to botulinum swells could likely be identified at the warehouse stage of distribution using Ellab or other sensing equipment capable of detecting the 1 bar pressure increase.However, the consumer could still not identify a post-warehousing botulinum swell. Consequently, aluminum cans, as currently designed, will never provide equal protection against botulism as steel cans with vacuum headspace.

Sadler, George
National Center for Food Safety & Technology
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