Cakes in jars, botulism and the early stages of the food safety system

Maybe you’ve got this bookmarked on your favorite crafty social media site: cake-in-a-jar recipes. Popular with students living in dorms and the Pinterest-savvy, these tiny desserts are tucked snugly into a small jar or can and are often baked in microwaves.

Cute as they may be, these treats come with a food safety threat you may not know about. The University of Wisconsin-Extension writes that cakes and breads simply cannot be safety canned, because they present an inherent risk for Clostridium botulinum, the bacteria that creates botulism toxin.

The thing is, cakes and certain breads don’t contain much acid. Placing them in a tight, sealed container, like a jar, allows the anaerobic (grows without oxygen) C. botulinum to grow uninhibited. Researchers at Kansas State University have shown that the bacteria can survive the baking process and thrive in sealed cans. This is why botulism outbreaks are so often associated with canned food products, mainly those that haven’t been pressure canned to destroy bacteria.

Canning conundrum

You’ve probably been told this before: “Don’t buy canned goods at the supermarket if they are dented!” Dents can be indicative of insufficient processing, meaning that bacteria kill-steps may not have been executed adequately. This issue came into public understanding after one of the very first modern, recorded foodborne illness outbreaks, the U.S. botulism outbreak of 1919 and 1920.

The multi-state outbreak killed 18 people and was traced back to canned black olives. For the at-the-time-new canning industry, the event nearly knocked canned products off shelves for good, had canners associations not leapt into action to support research into a new food safety system that would protect consumers and restore their reputation. A scientific commission founded by the industry devised new strategies to prevent the spread of illness, like processing olives at 240°F for 40 minutes. A public statewide inspection service was funded by the industries, which spread to other food products as well.

In an era where food safety practices have come so far, is it still unsafe to eat dented canned food? We’ll let the U.S. Food Safety Inspection Service answer that: “If a can containing food has a small dent, but is otherwise in good shape, the food should be safe to eat. Discard deeply dented cans.” The agency defines “deeply dented” as cans you can “lay your finger into,” often with sharp points.