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Slow Roasting a Turkey.. Food Safety.... HACCP test study...

post #1 of 17
Thread Starter 
Interesting read.... Interesting results....

HACCP AND SLOW-ROASTING TURKEYS by O. Peter Snyder, Jr., Ph.D Hospitality Institute of Technology and Management November 2008 edition


Introduction
Slow roasting turkey overnight seems to be a very common practice dating from the 1930s. There has been a persistent question, however, about the microbiological safety of slow-roast poultry, especially in terms of the production of Staphylococcus aureus toxin. In 1988, a well-done study was run at the University of Minnesota, Department of Food Science, by Eckner, Zottola, and Gravani, which provided the answer to the question of safety.
The study
Four frozen turkeys were used in the study. The turkeys were thawed in a refrigerator. The weight of the turkeys ranged from 11.7 to 25.5 pounds. Hence, they would take different times to cook. The carcasses were thoroughly washed, dried with a paper towel, and were stuffed with stuffing prepared using a standard recipe formulation. Cultures of Staphylococcus aureus, Salmonella typhimurium, and Clostridium perfringens were added to the stuffing of two turkeys. The population of each organism ranged from 100,000 per gram to 10,000,000 per gram of stuffing.
The stuffed turkeys were placed in a preheated, 350°F oven and baked for 1 hour. A cooking curve for a 29-lb. turkey is shown at Figure 1 (Eckner, et al., 1988).
Figure




Figure 1. Rate of heat penetration at the slowest heating points in 29-lb. turkey
OPS-papers-for-publication:turkey-papers-on-web-OPS / web:Documents: Turkey rev 11/5/08 print 12:48 PM 11/24/08

The temperature of the oven was then reduced to 225°F, and the turkeys were roasted an additional 12 hours. If the juice of the turkeys was pink. The turkeys were roasted an additional 1 to 2 hours at 300°F, or 1 hour at 350°F. A critical fact was that the final temperature of the stuffing was 165°F. The longest time between start of cook and getting to above the safe temperature of 130°F for the slowest cooking / largest turkey was about 8 hours.
As expected, no salmonellae or staphylococci was recovered. They were killed above 130°F as the turkey was cooking. Actually, if the stuffing had been sampled at 140 to 150°F, they would have found that these organisms would be dead, considering that 140°F for 12.7 minutes gives a 7D reduction of Salmonella in beef.
At the end of cooking, the stuffing and turkey were still positive for C. perfringens, as expected. Temperatures above 130°F are lethal for salmonellae and staphylococci, as these are vegetative pathogens. However, the spores of C. perfringens survive 165°F. Some of the C. perfringens spores may germinate to vegetative cells during a slow cook, but vegetative C. perfringens is very easy to inactivate. Therefore, when the turkey reaches 140°F, the vegetative C. perfringens, if produced, is destroyed. Once cooked, the turkeys cooked in this manner would be safe as long as they are above 130°F. Of course, uneaten portions of the stuffing (and turkey) must be handled properly to prevent C. perfringens "toxinfection" from the outgrowth of the spores during inadequate hot holding below 130°F or cooling too slowly to refrigeration temperatures.
How long does one have in cooking to get above the safe temperature of 130°F? Willardsen et al. (1978) reported on the multiplication of the C. perfringens vegetative cells in precooked hamburger during slow come-up in cooking. If the time to go from 50 to 130°F was about 7.6 hours, the vegetative cells might multiply 10,000 to 1. If the time was 5.8 hours, the multiplication would be about 1,000 to 1. If the time was 3.5 hours, the multiplication would be about 10 to 1. So, slow cooking might permit C. perfringens vegetative cell multiplication. By the time the hamburger reached 140°F, all of the C. perfringens vegetative cells that had multiplied will be destroyed. They used C. perfringens strains that multiplied about one every 7.5 minutes at 113°F. Common illness strains multiply more like once every 15 minutes at 113°F. Hence, this experiment was looking for extremes of safety. The times would probably be twice that reported for more "normal" C. perfringens.
From a HACCP perspective, what would be our concern? It would be toxin production from S. aureus growth during cooking. However, in raw turkey / food, S. aureus does not multiply, because there are competitive spoilage microorganisms. Therefore, with raw turkey, it would not multiply during cooking. Even if it did, as on cooked turkey with 100 S. aureus per gram, which was slowly reheated, the fastest I have found S. aureus to multiply is about once every 20 minutes in milk--3 times slower than the C. perfringens experiment by Willardsen et al. Staphylococcus aureus would have to multiply at least 1,000 to 1, or 10 generations, to make enough toxin to make anyone ill. The danger time to go from 50 to 130°F in cooked food starting with 100 S. aureus per gram would be expected to be approximately 3 times that of C. perfringens, or 15 hours. Note, this shows that the FDA-required food reheating to 165°F and holding for 15 seconds in less than 2 hours has absolutely no scientific validity. There is a small reason to set a minimum time for raw food cook come-up, but no justification for reheating as a safety control.
OPS-papers-for-publication:turkey-papers-on-web-OPS / web:Documents: Turkey rev 11/6/08 print 12:48 PM 11/24/08 2

It is true that there is a phenomenon whereby Salmonella can double or triple in resistance to inactivation if it spends some time at about 110F, which it will during slow cooking. However, it makes no difference; 12.7 minutes at 140°F gives a 10,000,000-to-1 kill (7D reduction). Assume that the time becomes 45 minutes. During slow cooking, the food still spends plenty of time at lethal temperatures above 130°F to kill all vegetative pathogens.
As a final point, remember, the code says that raw, potentially hazardous food must be held at 41F. There is no science for any temperature by itself. There must be time factored in, because Listeria monocytogenes, Yersinia enterocolitica , and Aeromonas hydrophila all begin to grow at 29.3°F. If we choose 7 days at 41°F as a control, which actually allows for about 10 multiplications of L. monocytogenes in 7 days, or if 45°F, 4 days, or if 50°F, 2.4 days, and if 110°F, 4.5 hours, all of these times and temperatures allow for the same amount of growth (Snyder, 1998). When we use HACCP in retail food operations, no one needs to measure the refrigerators again in terms of raw food hazard control. The vegetative pathogens will be killed in cooking.
There is getting to be an extensive body of science indicating that below about 55 to 60°F, food "spoils safe." The FDA has provided no justification for imposing a raw food 41°F cold-holding temperature. Epidemiological experience of the last 100 years suggests that food held at 55 to 60°F has limited pathogen growth and spoils safe. There are many quality reasons for keeping raw food at 28 to 32°F. However, this is shelf life and quality, and not safety.

References:
Eckner, K.F., Zottola, E.A., and Gravani, R.A. 1988. The microbiology of slow-roasted, stuffed turkeys. Dairy Food Sanit. 8(7):344-347.
FDA Food Code. 1999. U.S. Public Health Service, U.S. Dept. of Health and Human Services. Pub No. PB99-115925. Washington, DC.
Snyder, O.P. 1998. Updated guidelines for use of time and temperature specifications for holding and storing food in retail food operations. Dairy Food Environ. Sanit. 18(9):574-579.
Willardsen, R.R., Busta, F.F., Allen, C.E., and Smith, L.B. 1978. Growth and survival of Clostridium perfringens during constantly rising temperatures. J. Food Sci. 43:470-475.
OPS-papers-for-publication:turkey-papers-on-web-OPS / web:Documents: Turkey rev 11/6/08 print 12:48 PM 11/24/08
post #2 of 17

Good stuff Dave! 

 

My mom used to slow oven roast her stuffed birds overnight.  That's how she learned to do it from her mother.  I did it at least once I can remember, maybe more, but just like my mom's birds the white meat came out dry and chalky.  I really didn't care for turkey as a result.  Her internal temps were high enough obviously that we never got sick.   

 

Much later I read in a cookbook about cooking whole turkeys at higher temps and not stuffing them.  I was amazed at the difference the first time I cooked one that way, how juicy and tender it was.  Brining took it to a whole 'nuther level.  Been doing it that way ever since whether oven, grill, or smoker. 

 

I still can't bring myself to stuff a bird.  Thankfully my wife feels the same way.   

post #3 of 17
Thread Starter 
The best bird I had years ago was slow cooked at 180 deg. F for 24 hours.... Not stuffed.... I'm sure the bird had to be a specific size +/-... Moist, fall of the bone... I never knew turkey could be eaten without a beer to wash every bite down... before that bird, the turkey meat would stick in my throat every bite.... gawd awful stuff....
post #4 of 17

This is going to be interesting to watch. I got serve safe certified due to work sometime back and this obviously goes against the grain of their's and FDA say-so.

 I know at least one member may contest these findings.

 I feel a little better now, I've smoked 18 lb turkeys on an ECB for many, many years. No idea what the cooking temps were (cold-ideal-hot, when the guage used to work). It took way longer than oven ever did but oh so worth it. A few times the bird was so tender I picked it up by the breast and it fell apart. I was holding the breast and the rest just stayed there LOL.

 After the serve safe classes I began to question just how lucky I had been so far. Coming here and the safety first environment, I am even more concerned.

 This study makes alot of sense of my past experiances. I am very anal about cooking to safe temps these days. I mean, measured safe temps, not just time or a silly plastic popper.

post #5 of 17

This is great info and verifies that there is no reason to tell guys to Toss an Injected or Therm Probed from Raw, Roast because it didn't get above 140°F in EXACTLY 4 Hours.

 

As far as ServSafe and USDA/FDA Food Code having stricter Temps and Times...Their Guidelines are for an added Margin of Safety to protect the Public relying on Food Service Workers to keep them from getting ill. We all have seen restaurants staffed with everything from highly trained Pro Chefs to High School Kids that couldn't give a Crap how food is handled and have to be constantly reminded to Wash Their Hands! Having at least one person per shift ServSafe or equivient, certified means there should be at least one person watching whats going on and monitoring food safety. Thanks Dave...JJ

post #6 of 17

That is a good read. I guess this is similar to cooking sous vide where the meat is held at high temps long enough to kill everything. The key of course is having calibrated equipment to be 100% sure that you have obtained the proper temps for the proper times. Thanks Dave. 

post #7 of 17

I mis-judged you ChefJJ. I thought for sure you would contest these results. ServSafe is geared more toward safe food handling of cooked foods than the actual cooking of foods. 

post #8 of 17
Thread Starter 
Quote:
Originally Posted by mosparky View Post

I mis-judged you ChefJJ. I thought for sure you would contest these results. ServSafe is geared more toward safe food handling of cooked foods than the actual cooking of foods. 

I read the complete document and the test results.... I find the facts conclusive, as to the destruction of food borne pathogens...

Is there something, the way the testing was done, that is not "kosher" ?? What part of the test and results do you have objection with ??

I may not know much, but I did work in the quality assurance laboratory, for a major corporation, for 26 ish years...
post #9 of 17
post #10 of 17

Dave, you mis-understood. I thought Chef, being a servsafe instructor would take exception to these findings. I was wrong.

 Many, including myself have confused servsafe guidelines with food prep. My mistake.

As a layman I only understood enough to know it sounded legit and past experience supports my thoughts.

post #11 of 17
Thread Starter 
I think what they did was..... Look at what was in print and do a study, knowing food borne pathogens die at a certain temp... given enough time, they will die at a lower temperature..... Lowering the pathogen 10 million to 1, a 10 -7 reduction is way beyond safe... I think this was an exercise to confirm what the scientist thought... also the "safe food storage temp" where food safe bacteria can grow is really interesting... Epidemiological experience of the last 100 years suggests that food held at 55 to 60°F has limited pathogen growth and spoils safe..... Now that confuses me... seriously.... I guess the stuff that grows will be killed at pasteurization temps... especially when you look at the temperature range for growth...

Anyway, I really find this food safety stuff interesting... Almost looks as if you find "road kill", if you cook it long enough and at the proper temperature, if "MAY" be safe to eat.... I'm not testing it.... no way... I've got enough good eats to eat as it is....

After working in a quality assurance lab for ~27 years, I still dig into this stuff for giggles.....


Temperature Time Temperature Time
°F (°C) (Minutes) °F (°C) (Seconds)

130 (54.4) 112 min... 146 (63.3) 169 sec
131 (55.0) 89 min.... 147 (63.9) 134 sec
132 (55.6) 71 min.... 148 (64.4) 107 sec
133 (56.1) 56 min.... 149 (65.0) 85 sec
134 (56.7) 45 min.... 150 (65.6) 67 sec
135 (57.2) 36 min.... 151 (66.1) 54 sec
136 (57.8) 28 min.... 152 (66.7) 43 sec
137 (58.4) 23 min.... 153 (67.2) 34 sec
138 (58.9) 18 min.... 154 (67.8) 27 sec
139 (59.5) 15 min.... 155 (68.3) 22 sec
140 (60.0) 12 min.... 156 (68.9) 17 sec
141 (60.6) 9 min...... 157 (69.4) 14 sec
142 (61.1) 8 min...... 158 (70.0) 0 sec
143 (61.7) 6 min.......
144 (62.2) 5 min.......
145 (62.8) 4 min.......

Table C.1: Pasteurization times for beef, corned beef, lamb, pork and cured pork (FDA, 2009, 3-401.11.B.2).

post #12 of 17

Now the whole thing confuses me. Other post suggest that the temps will not kill certain bad stuff that can be present if cooking temps do not raise meat (turkey) above 140 in 4 hrs. Think I'll just play it safe and shoot for the 140 in less than 4 hrs. I can live with that...literally.

post #13 of 17
Thread Starter 
That's cool... Your food will be safe, for sure.....

Dave
post #14 of 17

You don't need to worry about 40-140 in 4, aka the Rule...IF...You pay attention to what you are doing, start to finish...Keep everything Clean and Food Cold, grocery store to smoker. Babysit the Smoker and keep temps above 225°F, Without Fail. Monitor the meat Internal Temp so you know you reached a Safe Finished IT...That's IT!  Three simple steps and you won't need to sweat the Rule...JJ

post #15 of 17

JJ i was just answering another post about smoking a turducken.

 All of the shops that make the turducken down here have labels on the product that do not recommend low and slow smoking as the internal birds take to long to reach a safe temp? i can see the point as you have 3 different birds stuffed inside each other,

  since the duck and the chicken and the turkey have been deboned they have had a lot of handling while thawed.

 Any thoughts?

post #16 of 17
Thread Starter 
Seems to me, not too long ago, pork had to be cooked to ~160 ish deg. F.... A study decided 145 deg. F was adequate to make the meat safe to eat.... That totally changed the food industry.....

Now we are looking at another study that "could" have a revolutionary effect on the food industry...
post #17 of 17

There are exceptions to every rule. A Turducken is one I would include here. Big difference from an injected Pork Butt. Two out of the three birds are known to be bacteria layden due to the style of processing. Now they are layered together with mass produced stuffing. I would not be low and slow smoking, 325+ on these birds...JJ

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