Food Danger Zone vis-á-vis Sous Vide Preparation

[pmillen]

The posts in this section are re-inspiring me.  I've been thinking of cold smoking a steak with an Amaz-N-Tube Smoker inside my Cookshack PG-500 or Bradley (neither one running) prior to cooking it sous vide.  In both the cold smoking step and the sous vide cooking step the temperatures will probably be in the food danger zone where bacteria grows.



Searing the steak after sous vide cooking will certainly kill the bacteria but I've been told that bacteria waste products will still exist and are also dangerous.  It seems to me that they'll be seared, too, whatever they are.

Should I be concerned?

[muebe]

You do not need to be concerned. A steak held at a water temp of 130F or higher over several hours will be fine.

You can freeze the steak and let it cold smoke as it thaws.

An hour of cold smoke for a steak is plenty IMHO.

Cold smoke then bag the steak. Let it mellow overnight in the fridge then sous vide the next day.

You can sear it for a couple minutes on the grill or hit it with a torch

[pmillen]

So there's no concern that bacterial toxins are not destroyed by cooking?  Even when the steak has spent and hour in the smoker where bacteria may multiply and produce toxins and several hours sous vide cooking where they may also multiply and produce toxins?

A single bacteria at time zero can multiply to 2 million in just 7 hours. The more bacteria that are present the more toxins produced and the more ill you are likely to become.

I've been mulling this over for a couple of years.  I know that sous vide is practiced regularly by thousands of professional chefs and perhaps as many amateurs in their respective homes and I've not read about anyone becoming ill.  But we may not hear about it if it happened.

I have one of the authoritative books on the subject, Beginning Sous Vide, and the word "toxin" is not in it.  (I have it on an e-reader, so the search is easy.)  That seems short-sighted to me.

[muebe]

130F will kill bacteria it just takes much longer. At 165F they are killed in several seconds. At 130F it can take an hour or longer depending on the size and type of meat.

Paul there is always a concern about bacteria. That is why you must understand what it is involved to safely cook with sous vide.

People get sick all the time from leaving out potato salad too long for example. Or under cooking ground beef.

You must be safe during all forms of cooking.

Sous vide does not follow under standard guidelines because it is not a standard form of cooking. Food is cooked at lower temps over much longer periods. The short ribs I recently did went 72 hours at 135F and they were amazing. Fully cooked and I did not get sick.

Also the air is removed when vac sealing. That reduces the available oxygen to the bacteria and allows the water to make contact with the food. This is different then cooking in a oven with hot air for example. Try sticking your hand into a 200F oven and it probably won't burn for a while. Now stick you hand in 200F water and well that is a different story! That is why sous vide can be safe at lower temps. The thermal transfer rate to the meat is much higher.

There are guidelines for Sous Vide that are available for proper temps and times.

Obviously if you have doubts are concerns you can avoid cooking this way altogether.

[pmillen]

Obviously if you have doubts are concerns you can avoid cooking this way altogether.

   Yeah, that's what has caused me to wait a couple of years.

I'm not concerned about live bacteria.  They'll be killed by the sear.  I'm concerned about the dangerous toxins they produce that are not destroyed by cooking.

Your point about a vacuum is important.  I'll do some research to see if the bacteria are anaerobic.

Thanks, you may be moving me closer.

[pz]

Here's an interesting article from A&M

http://aggie-horticulture.tamu.edu/food-technology/bacterial-food-poisoning/

[Hub]

I can't speak to sous vide methodology since I've never done it and haven't researched it.  However, reverse searing a steak for a reasonable period providing the following apply is quite safe:

1.  The steak is good and fresh in the first place
2.  The steak is refrigerated
3.  Reverse searing (smoking) is done for 30-60 minutes (that's all it takes!)
4.  The steak is then seared to the desired level of doneness or wrapped and returned to refrigeration for later cooking

The time in "the zone" for bacterial growth is inconsequential. 

Several common sense factors come into play.  If the steak is past sell-by or serve-by date -- toss it.  Cooking a refrigerated steak is always much easier than a room-temperature steak because it gives you a longer cook with more control over the internal temp, especially for rare, medium-rare and medium doneness.  If the meat smells bad, cooking it won't make it good 

Hub

[pmillen]

130F will kill bacteria it just takes much longer. ... At 130F it can take an hour or longer depending on the size and type of meat.

Muebe, can you provide a citation?  I ask because I’ve done a lot of research and everything I locate is contrary.

This is from the United Kingdom Food Standards Agency.  It’s retained in the UK National Archives at http://archive.food.gov.uk/hea/teachers/plainenglish/part2.html. 

"At a temperature of about 37°C (human body temperature) pathogens multiply most quickly but as the temperature continues to rise, their rate slows down and they will stop growing altogether above 63°C [145°F]. However, in order to destroy bacteria, temperatures must rise further [emphasis mine]. A temperature of 70°C [158°F] for 2 minutes is recommended as a means of killing pathogens during the normal cooking process."

[muebe]

Here is a link to a wealth of information on Sous Vide. This is where I did my research before I started. Below the link is information I copied directly from there...

http://www.douglasbaldwin.com/sous-vide.html

You were probably taught that there’s a “danger zone” between 40°F and 140°F (4.4°C and 60°C). These temperatures aren’t quite right: it’s well known that food pathogens can only multiply between 29.7°F (-1.3°C) and 126.1°F (52.3°C), while spoilage bacteria begin multiplying at 23°F (-5°C) (Snyder, 2006; Juneja et al., 1999; FDA, 2011). Moreover, contrary to popular belief, food pathogens and toxins cannot be seen, smelt, or tasted.

So why were you taught that food pathogens stop multiplying at 40°F (4.4°C) and grow all the way up to 140°F (60°C)? Because it takes days for food pathogens to grow to a dangerous level at 40°F (4.4°C) (FDA, 2011) and it takes many hours for food to be made safe at just above 126.1°F (52.3°C) – compared with only about 12 minutes (for meat) and 35 minutes (for poultry) to be made safe when the coldest part is 140°F (60°C) (FSIS, 2005; FDA, 2009, 3-401.11.B.2). Indeed, the food pathogens that can multiply down to 29.7°F (-1.3°C) – Yersinia enterocolitica and Listeria monocytogenes – can only multiply about once per day at 40°F (4.4°C) and so you can hold food below 40°F (4.4°C) for five to seven days (FDA, 2011). At 126.1°F (52.3°C), when the common food pathogen Clostridium perfringens stops multiplying, it takes a very long time to reduce the food pathogens we’re worried about – namely the Salmonella species, Listeria monocytogenes, and the pathogenic strains of Escherichia coli – to a safe level; in a 130°F (54.4°C) water bath (the lowest temperature I recommend for cooking sous vide) it’ll take you about 2½ hours to reduce E. coli to a safe level in a 1 inch (25 mm) thick hamburger patty and holding a hamburger patty at 130°F (54.4°C) for 2½ hours is inconceivable with traditional cooking methods – which is why the “danger zone” conceived for traditional cooking methods doesn’t start at 130°F (54.4°C). [Note that Johnson et al. (1983) reported that Bacillus cereus could multiply at 131°F/55°C, but no one else has demonstrated growth at this temperature and so Clostridium perfringens is used instead.]

Pasteurization is a combination of both temperature and time. Consider the common food pathogen Salmonella species. At 140°F (60°C), all the Salmonella in a piece of ground beef doesn’t instantly die – it is reduced by a factor ten every 5.48 minutes (Juneja et al., 2001). This is often referred as a one decimal reduction and is written D606.0 = 5.48 minutes, where the subscript specifies the temperature (in °C) that the D-value refers to and the superscript is the z-value (in °C). The z-value specifies how the D-value changes with temperature; increasing the temperature by the z-value decreases the time needed for a one decimal reduction by a factor ten. So, D666.0 = 0.55 minutes and D546.0 = 54.8 minutes. How many decimal reductions are necessary depends on how contaminated the beef is and how susceptible you are to Salmonella species – neither of which you’re likely to know. FSIS (2005) recommends a 6.5 decimal reduction of Salmonella in beef, so the coldest part should be at least 140°F (60°C) for at least 6.5D606.0 = 35.6 minutes.

The rate at which the bacteria die depends on many factors, including temperature, meat species, muscle type, fat content, acidity, salt content, certain spices, and water content. The addition of acids, salts, or spices can all decrease the number of active pathogens – this is why mayonnaise (with a pH less than 4.1) does not need to be cooked. Chemical additives like sodium lactate and calcium lactate are often used in the food industry to reduce the risk of spore forming pathogens like Clostridium species and Bacillus cereus (Aran, 2001; Rybka-Rodgers, 2001).

Pasteurization Time for Lean Fish
(starting at 41°F / 5°C and put in a 131–140°F / 55–60°C water bath)
55°C   56°C   57°C   58°C   59°C   60°C
Thickness   131°F   133°F   134.5°F   136.5°F   138°F   140°F
5 mm   2½ hr   1¾ hr   1¼ hr   50 min   35 min   30 min
10 mm   2¾ hr   2 hr   1½ hr   60 min   45 min   35 min
15 mm   2¾ hr   2 hr   1½ hr   1¼ hr   55 min   50 min
20 mm   3 hr   2¼ hr   1¾ hr   1½ hr   1¼ hr   60 min
25 mm   3¼ hr   2½ hr   2 hr   1¾ hr   1½ hr   1¼ hr
30 mm   3¾ hr   3 hr   2½ hr   2 hr   1¾ hr   1¾ hr
35 mm   4 hr   3¼ hr   2¾ hr   2½ hr   2¼ hr   2 hr
40 mm   4½ hr   3¾ hr   3 hr   2¾ hr   2½ hr   2¼ hr
45 mm   4¾ hr   4 hr   3½ hr   3¼ hr   2¾ hr   2½ hr
50 mm   5¼ hr   4½ hr   4 hr   3½ hr   3¼ hr   3 hr
55 mm   5¾ hr   5 hr   4½ hr   4 hr   3¾ hr   3½ hr
60 mm   6¼ hr   5½ hr   5 hr   4½ hr   4 hr   3¾ hr
65 mm   7 hr   6 hr   5½ hr   5 hr   4½ hr   4¼ hr
70 mm   7½ hr   6¾ hr   6 hr   5½ hr   5 hr   4¾ hr

Pasteurization Time for Fatty Fish
(starting at 41°F / 5°C and put in a 131–140°F / 55–60°C water bath)
55°C   56°C   57°C   58°C   59°C   60°C
Thickness   131°F   133°F   134.5°F   136.5°F   138°F   140°F
5 mm   4¼ hr   3 hr   2 hr   1½ hr   60 min   40 min
10 mm   4¼ hr   3 hr   2 hr   1½ hr   1¼ hr   50 min
15 mm   4½ hr   3¼ hr   2¼ hr   1¾ hr   1¼ hr   60 min
20 mm   4¾ hr   3½ hr   2½ hr   2 hr   1½ hr   1¼ hr
25 mm   5 hr   3¾ hr   2¾ hr   2¼ hr   1¾ hr   1½ hr
30 mm   5¼ hr   4 hr   3¼ hr   2½ hr   2¼ hr   2 hr
35 mm   5½ hr   4¼ hr   3½ hr   3 hr   2½ hr   2¼ hr
40 mm   6 hr   4¾ hr   4 hr   3¼ hr   3 hr   2½ hr
45 mm   6½ hr   5¼ hr   4¼ hr   3¾ hr   3¼ hr   3 hr
50 mm   7 hr   5¾ hr   4¾ hr   4¼ hr   3¾ hr   3¼ hr
55 mm   7½ hr   6¼ hr   5¼ hr   4¾ hr   4¼ hr   3¾ hr
60 mm   8 hr   6¾ hr   5¾ hr   5¼ hr   4¾ hr   4¼ hr
65 mm   8½ hr   7¼ hr   6¼ hr   5¾ hr   5¼ hr   4¾ hr
70 mm   9¼ hr   8 hr   7 hr   6¼ hr   5¾ hr   5¼ hr


Pasteurization Time for Poultry
(starting at 41°F / 5°C and put in a 134.5–149°F / 57–65°C water bath)
134.5°F   136.5°F   138°F   140°F   142°F   143.5°F   145.5°F   147°F   149°F
Thickness   57°C   58°C   59°C   60°C   61°C   62°C   63°C   64°C   65°C
5 mm   2¼ hr   1¾ hr   1¼ hr   45 min   35 min   25 min   18 min   15 min   13 min
10 mm   2¼ hr   1¾ hr   1¼ hr   55 min   40 min   35 min   30 min   25 min   20 min
15 mm   2½ hr   1¾ hr   1½ hr   1¼ hr   50 min   45 min   40 min   35 min   30 min
20 mm   2¾ hr   2 hr   1¾ hr   1¼ hr   1¼ hr   55 min   50 min   45 min   40 min
25 mm   3 hr   2¼ hr   2 hr   1½ hr   1½ hr   1¼ hr   1¼ hr   60 min   55 min
30 mm   3¼ hr   2¾ hr   2¼ hr   2 hr   1¾ hr   1½ hr   1½ hr   1¼ hr   1¼ hr
35 mm   3¾ hr   3 hr   2½ hr   2¼ hr   2 hr   1¾ hr   1¾ hr   1½ hr   1½ hr
40 mm   4 hr   3¼ hr   2¾ hr   2½ hr   2¼ hr   2 hr   2 hr   1¾ hr   1¾ hr
45 mm   4½ hr   3¾ hr   3¼ hr   3 hr   2¾ hr   2½ hr   2¼ hr   2 hr   2 hr
50 mm   4¾ hr   4¼ hr   3¾ hr   3¼ hr   3 hr   2¾ hr   2½ hr   2½ hr   2¼ hr
55 mm   5¼ hr   4½ hr   4 hr   3¾ hr   3½ hr   3¼ hr   3 hr   2¾ hr   2¾ hr
60 mm   5¾ hr   5 hr   4½ hr   4¼ hr   3¾ hr   3½ hr   3¼ hr   3¼ hr   3 hr
65 mm   6¼ hr   5½ hr   5 hr   4½ hr   4¼ hr   4 hr   3¾ hr   3½ hr   3¼ hr
70 mm   7 hr   6 hr   5½ hr   5 hr   4¾ hr   4½ hr   4¼ hr   4 hr   3¾ hr

Pasteurization Time for Meat (Beef, Pork, and Lamb)
(starting at 41°F / 5°C and put in a 131–151°F / 55–66°C water bath)
55°C   56°C   57°C   58°C   59°C   60°C
Thickness   131°F   133°F   134.5°F   136.5°F   138°F   140°F
5 mm   2 hr   1¼ hr   60 min   45 min   40 min   30 min
10 mm   2 hr   1½ hr   1¼ hr   55 min   45 min   40 min
15 mm   2¼ hr   1¾ hr   1½ hr   1¼ hr   60 min   55 min
20 mm   2½ hr   2 hr   1¾ hr   1½ hr   1¼ hr   1¼ hr
25 mm   2¾ hr   2¼ hr   2 hr   1¾ hr   1½ hr   1½ hr
30 mm   3 hr   2½ hr   2 hr   2 hr   1¾ hr   1½ hr
35 mm   3¼ hr   2¾ hr   2¼ hr   2 hr   2 hr   1¾ hr
40 mm   3½ hr   3 hr   2½ hr   2¼ hr   2¼ hr   2 hr
45 mm   4 hr   3¼ hr   3 hr   2¾ hr   2½ hr   2¼ hr
50 mm   4½ hr   3¾ hr   3¼ hr   3 hr   2¾ hr   2½ hr
55 mm   5 hr   4¼ hr   3¾ hr   3½ hr   3 hr   3 hr
60 mm   5¼ hr   4¾ hr   4¼ hr   3¾ hr   3½ hr   3¼ hr
65 mm   6 hr   5¼ hr   4¾ hr   4¼ hr   4 hr   3¾ hr
70 mm   6½ hr   5¾ hr   5¼ hr   4¾ hr   4¼ hr   4 hr

61°C   62°C   63°C   64°C   65°C   66°C
Thickness   142°F   143.5°F   145.5°F   147°F   149°F   151°F
5 mm   25 min   25 min   18 min   16 min   14 min   13 min
10 mm   35 min   30 min   30 min   25 min   25 min   25 min
15 mm   50 min   45 min   40 min   40 min   35 min   35 min
20 mm   60 min   55 min   55 min   50 min   45 min   45 min
25 mm   1¼ hr   1¼ hr   1¼ hr   60 min   55 min   55 min
30 mm   1½ hr   1½ hr   1¼ hr   1¼ hr   1¼ hr   1¼ hr
35 mm   1¾ hr   1½ hr   1½ hr   1½ hr   1¼ hr   1¼ hr
40 mm   1¾ hr   1¾ hr   1¾ hr   1½ hr   1½ hr   1½ hr
45 mm   2¼ hr   2 hr   2 hr   1¾ hr   1¾ hr   1¾ hr
50 mm   2½ hr   2¼ hr   2¼ hr   2 hr   2 hr   2 hr
55 mm   2¾ hr   2¾ hr   2½ hr   2½ hr   2¼ hr   2¼ hr
60 mm   3 hr   3 hr   2¾ hr   2¾ hr   2½ hr   2½ hr
65 mm   3½ hr   3¼ hr   3¼ hr   3 hr   3 hr   2¾ hr
70 mm   3¾ hr   3¾ hr   3½ hr   3¼ hr   3¼ hr   3¼ hr

[pmillen]

Thanks Meube.  I obviously have more reading to do.  If the pasteurization (microbe killing) during sous vide reduces the amount of toxin left behind then I only need to be concerned with the cold smoke step.

[pmillen]

The time in "the zone" for bacterial growth is inconsequential.

Hub, I would agree if I knew for certain that the final cook (sear) destroys both the bacteria and bacterial toxins.  I think you are saying that the amount of each doesn't matter when starting the sear 'cause they'll both be destroyed.  But it appears that most of the bacterial toxins are not destroyed by heat.

From:  Preventing Food Poisoning And Food Infection, The University of Georgia College of Agricultural & Environmental Sciences Cooperative Extension Service, Estes Reynolds, George Schuler, William Hurst & P.T. Tybor, Extension Food Science, Food Poisoning Microorganisms, Staphylococcus aureus, pg. 2.

"Staphylococcus is a true food poisoning organism. … It produces a heat stable toxin when allowed to grow… This bacterial growth may not cause any off color, odor, or textural or flavor change, but the toxin will be secreted into the food. 

"Staphylococcus toxin is not markedly affected by heating or freezing as it is heat stable. Even if the food is heated before eating, the poison in the food will cause illness although the heat has killed the bacterial cells."

This citation is typical of the text describing the eight most common causes of food poisoning.

So I'm still trying do determine if a really hot sear will destroy (burn) the toxins (hopefully they're only on the surface).

[drholly]

You raise some very interesting questions, Paul. I look forward to more on this thread.

[TentHunteR]

Muebe does a good job explaining the times/temps for pasteurization, but one clarification, if I may:

Also the air is removed when vac sealing. That reduces the available oxygen to the bacteria and allows the water to make contact with the food.

Paul asked about Anearobic bacteria:

Vacuum sealing helps guard against spoilage bacteria, but NOT anaerobic bacteria. C. botulinum is an obligate anaerobe and actually thrives in a low or no oxygen environment. E. Coli & Salmonella are both facultative anaerobes capable of switching to "fermentation mode" in low/no oxygen environment.


Now, that does not mean Sous Vide is dangerous, it's the just the info on the bacteria.


As Muebe explains, bacteria needs time, even at these temps, to reach potentially risky levels. Anaerobic Bacterial Mesophiles multiply fastest between 68° - 113° F (117° per FDA standards) with bacterial growth severely dropping off after that and stopping around 118°.  I like to consider this 68° - 113° range to be the "Extreme" Danger Zone temps. 

The recommended Sous Vide cooking temp for beef is 134° or higher. At 135° most surface bacteria should be pasteurized within 37 minutes. That is well below the way oversimplified "1 hour danger zone" recommendation by the FDA & USDA.

The recommended Sous Vide cooking temp for chicken is 146° or higher.

The recommended Sous Vide cooking temp for Turkey or Duck leg is 176° or higher.
Admittedly, this inconsistency has me wondering a little - Maybe its due to thickness or texture:

The recommended Sous Vide cooking temp for Pork varies from 134° - 160° (depending on the cut & thickness)
(I would choose to use 145° -160°)



Here's a good read about this: http://www.amazingribs.com/tips_and_technique/food_safety.html  - Read the section entitle, "What the USDA Doesn't Tell You."

It basically boils down to your personal comfortable level. If your unsure about this cooking method then either don't use it or make adjustments you feel comfortable with.

[sparky]

I think the only way i'm going to try eating some of this sous vide is if it's produced by muebe.  I know he wouldn't do anything to hurt me.