Modeling food held out on a hot day

The unofficial start of the summer is this weekend in the U.S. – Memorial day. Folks will be bbqing, cooking out, grilling out, whatever.

There’s a recommendation from USDA that on a hot day, above 90F/32C that food shouldn’t sit out for more than an hour. I couldn’t find a good reference for this. So I started texting Don.

He wasn’t answering. (I found out later it was because he was doing an interview with CBC, that’s a radio/TV network in Canada).

I started looking at a Conference for Food Protection document on how to handle food decisions at retail when the power goes out. Not exactly what I was looking for – all the modeling starts at 41F and doesn’t get as hot as I was looking for.

Then Don finally answered and suggested this paper on Salmonella in cut tomatoes.

Getting warmer.

I finally got into Combase and generated a couple of no-lag growth models for staph (in something like potato salad) and Salmonella. 

The staph model doesn’t go as high as 90F/32C so it’s a bit conservative different. But the Salmonella model shows a 1 log increase in just over an hour.

So yeah, hot days matter.

 

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About Ben Chapman

Dr. Ben Chapman is an associate professor and food safety extension specialist at North Carolina State University. As a teenager, a Saturday afternoon viewing of the classic cable movie, Outbreak, sparked his interest in pathogens and public health. With the goal of less foodborne illness, his group designs, implements, and evaluates food safety strategies, messages, and media from farm-to-fork. Through reality-based research, Chapman investigates behaviors and creates interventions aimed at amateur and professional food handlers, managers, and organizational decision-makers; the gate keepers of safe food. Ben co-hosts a biweekly podcast called Food Safety Talk and tries to further engage folks online through Instagram, Twitter, Facebook, YouTube and, maybe not surprisingly, Pinterest. Follow on Twitter @benjaminchapman.