Kill Temps: Pork & Trichinella


 

K Kruger

TVWBB 1-Star Olympian
(AKA trichina or trichinae)

A couple or three decades ago when many of us in the restaurant biz became aware of the possibility for lower finish internals in pork, 137F became the new number. As commercial pork had been getting increasingly (and unfortunately) leaner over the years, many chefs had all but abandoned bothering with simply preparing loins and tenderloins, instead using more labor- or time-intensive approaches (like marinades) in an effort to maintain moisture. Lower finish internals (which emanated from research but with little further details) were adopted wholesale, and many chefs I knew at the time re-introduced or introduced menu items they'd pretty much given up on--I know I did.

Several weeks ago, while in a discussion about pork, game meats, Trich and Salmonella, it arose that the kill point for Trich, a parisitic worm, is just as much a time @ temp issue as exists for the bacteria that cause food-borne illnesses. (Duh! Of course! I felt like such an idiot.)

In other words, once a particular temp is reached it becomes a matter of time at that temp for the kill step to be completed. Higher temps require shorter times and the times become shorter still as temps increase, till such a temp when the time is so short as to be considered 'instant'. (This is the same for bacteria. See here and here for time/temp info for meats and poultry.)

A gentleman involved in the discussion pointed us to the Code of Federal Regulations (specifically, 9CFR318.10, pp 244-256, revised in January of last year) that includes a time @ temp chart. It is based on the research of Tony Kotula, et al., from the 80s. Here:


Minimum Internal Temp


F ...... C ...... Minimum Time
________________________________

120 ... 49 ... 21 hours

122 ... 50 ... 9.5 hours

124 ... 51.1 ... 4.5 hours

126 ... 52.2 ... 2 hours

128 ... 53.4 ... 1 hour

130 ... 54.5 ... 30 min

132 ... 55.6 ... 15 min

134 ... 56.7 ... 6 min

136 ... 57.8 ... 3 min

138 ... 58.9 ... 2 min

140 ... 60 ... 1 min

142 ... 61.1 ... 1 min

144 ... 62.2 ... Instant

******************************

You'll note there is no 137 (which would come in around 2.3 min). I'm guessing that back then 137 was selected because that was the lowest temp that, when considering the probable time factor (the amount of time between hitting 137 and actually cutting the meat) coupled with the natural increase in internal temp that occurs during this rest, more than amounted to the just over 2 minutes necessary.

I'll reiterate: The instances of Trich in commercial pork are vanishingly rare but should not be assumed to be non-existant. Also: Bimetal analog therms should NOT be used for food safety purposes in thin items. Use a thermocouple or thermistor digital. (I don't use them for items of any thickness. Up to you.) Also: The chart above is for use with commercial pork, not wild game meats. They are susceptible to strains of Trich which are more temp resistant.
 
So, when that pork butt has been at a 165 degree plateau for an hour, I do at least have one reason not to be so annoyed.
icon_smile.gif
 
I recently read some articles of the health authority here in Germany. (about pork)
As @K Kruger wrote trichina is no longer that an big issue.
The health authority claims that an minimum core temp of 70°C (158°F) is necessary to kill e.g. Hepatitis E virus and other bacteria (Salmonellae and sarcosporidiosis).
So 144°F / 62.2 °C (Instant) is maybe enough for trichina but for me still to low. I never serve pork under 167°F/75°C core temp.

What do you think?
Am I wrong or too careful?

Jan
 
Kevin;
Thanks for this great info. I, before I became "old and feeble" hunted a good bit. Black Bear are subject to trichinosis. I was always careful to properly cook them just like pork in the "old days". I still take great care with my Thermapen on ALL meat to watch my temperatures. Most meat these days come from "meat factories" and that MAY increase the chance of contamination. We read of almost daily recalls of products (both meat and vegetables) so it pays to ALWAYS be alert and careful in our work with food. That, as you have pointed out in the past, includes site cleanliness as well a meat temperatures.

Keep on smokin',
Dale53:wsm:
 
"What do you think?
Am I wrong or too careful?"

Temperature recommendations are made with the idea that the all of the "bad stuff" will be gone at that temperature. The time/temperature charts are designed with the idea that if meat is held at a specific temperature for a length of time, all of the "bad stuff" will be gone also. Sous vide has changed the instant temperature recommendations. Using sous vide I can hold pork chops at 136F for an hour (well over the 3 min recommended time/temp) and have nice medium rare pork chops.

In the old days, a pork chopped cooked on the grill to this temperature would be dangerous to eat because the temperature wasn't held for the requisite 3 minutes. Understand and trust the science and you can have some nice juicy pork chops.

I cook them to 140F using these guidelines - https://www.seriouseats.com/2016/04/food-lab-complete-guide-to-sous-vide-pork-chops.html

Russell
 
It was known as far back as the 1970's that freezing pork also kills the Trich. I note that all American commercial pork is " previously handled frozen for safety". The last farm pig I got I froze at -2F for a couple weeks before using. the grower did offer a place to send a sample for testing But I had no plans to use right away anyhow.
 
I cook all my lean pork roasts to 140 and let them rest (tented)
Chops I do by feel ( like a steak) and let them rest also.
I like pink pork!

Tim
 

 

Back
Top