sous vide chuck roast

Sous Vide Temperature, Time, and Safety – The Basics

 

 

 

Despite the hype, Sous Vide is among the safest and simplest methods of cooking. Since it is typically conducted in a sealed environment, it is one of very few forms of cooking dedicated to the actual pasteurization of food. In all likelihood, primitive populations noticed that heat applied to food before consumption reduced the occurrence of food born illness, leading eventually to the discovery of pasteurization. Not to be confused with sterilization, pasteurization reduces bacterial levels to levels low enough to render them harmless. If temperature abuse occurs, it is conceivable that they could repopulate, so safe practice should be observed with all foods at all times.

Sous Vide Temperature and Time are simple but essential elements that form the keys to Sous Vide Success.

STARTING POINTS.

Racks that hold the packages vertically not only assure good circulation on the sides and below, but improve ease of handling. All Lipavi racks are configured to be vertical, with the versatility to be used in other positions as well.

Food that has been handled safely in advance should go into the bath either from a refrigerated state, 40F/4.5c, or, from the frozen state, typically 0F/-18C. Allow half an hour extra per inch of thickness if your project is frozen. Bringing food to “room temperature” before processing is not recommended, because it creates the risk of temperature abuse. Likewise, care must be taken to assure that there is ample separation between packages to assure the free circulation of water, which is the medium through which the heat is conducted. The combined volume of the packages should never exceed the volume of water in the vessel. Using racks of some sort assures that packages are prevented from drifting into contact with each other.

TEMPERATURE

Temperature determines the appearance of doneness. Higher temperatures also reduce processing time, but time has minimal effect on the visual appearance of doneness, the actual “color.”

Even the hardiest of bacteria have great difficulty surviving at temperatures greater than 122F/50C. In order to compensate for equipment accuracy issues, processing is not usually considered safe below 127F/53C. Some practitioners process SV as low as 122F/53C, but the interval should never exceed 2 hours. All temperatures higher than this are safe, but, typically, SV processing doesn’t exceed 183F/84C, which is the temperature required to denature most vegetables. Meat is not usually processed this high.

RARENESS

While beef, lamb, and some other meats are most commonly cooked with the appearance of “rareness” as the goal, the same basic principle of pasteurization applies to all meats. The lower the temperature, the more “raw” the meat will appear to be. Meat–ANY MEAT–can appear to be almost completely raw, and, yet, be safe to eat, as a result of SV processing (low temperature pasteurization).

If your 2” Rib Eye steak, for example, appears to be rare after being processed for 2 hours @129F, that same steak will have basically the same appearance after 6 hours or even more. Myoglobin (not blood) is the protein that contributes the red appearance to meat, and it will dissipate as a function of time, albeit slowly. If you continue to process that steak for 24 hours, you will see a lot of red liquid in the bag, which is the myoglobin draining out.

TIME

TIME determines texture/tenderness.

The longer meat is processed via SV, the more tender it will become. In the case of very tender steaks, they may be tender before they even go in the bag, but they will become more so as time passes. Tough cuts may take up to 72 hours to become tender, but even the toughest of cuts will eventually get tender, even @129F/54C. The presence of bone may interfere somewhat, and cuts with bones should be processed a little hotter–closer to 132F/55.5 is enough, though–a very small increment. The higher the temperature, the faster the tenderization process will occur, and the more “damage” to the structural integrity of meat will also occur. In this case, damage is defined as the dissolution and/or breakdown of cell walls. This is why seasoned practitioners usually shoot for lower temps and longer times.

IT’S AS SIMPLE AS THAT.

The Pinch Test

Time results may vary, so, the best way to tell if your meat is tender to your liking is to “pinch” it, while it is still in the bag. It’s pretty easy to tell using this method, even for the novice. You can also “crack the bag” and test for tenderness, as long as you reseal afterwards. Whether you feel confident or not determining tenderness by this method, you should do it as a matter of course. Eventually, you will notice the variations in resistance, and it will become useful as second nature.

Shocking

Shocking refers to putting a completed SV project into cold water, or ice water, to quickly reduce the temperature to safe levels (40F/4.5C). This cannot be achieved practically by just putting a hot package in a refrigerator, and, it also puts surrounding foods at risk by raising the temperature inside the fridge. Therefore, sealed packages to be served later should be cooled in ice water, or, at least, cold running tap water, to 70F/21C within two hours after processing, and to 40F/4.5C within two hours after that.

Complete shocking is not necessary if you plan to serve immediately. It is a good aesthetic practice to give the meat a few minutes to cool at room temperature so that searing or torching does not cause an increase in internal temperature.

Beef–fresh, cured, pickled, etc.

In order to be safe (and to pasteurize), processing temps start at 129F/54C. If there are bones still attached to the meat, I usually recommend 132F/55.5C to compensate for the difference in thermal conductivity of bone vs meat. Temperatures can range up to as high as you want, but, to fully take advantage of the SV process, they rarely go above 150F/65.5C for beef. The appearance of doneness that we refer to as “rare” is right there @129F/54C, and graduates to well done subjectively somewhere between 140F/60C and 150F/65.5C. These principles apply to all meats, not just beef.

That being said, tender cuts like Filet, NY, etc. achieve pasteurization @129F Rare within 4 hours. Tough cuts like Brisket, Chuck, Eye of Round, Round, etc., achieve the pasteurized state at the same rate, but take longer, or, even, MUCH longer to achieve tenderness, depending on the temperature used. @129F/54C, some cuts can take as long as 96 hours to become tender. Since MOST tough cuts are preferred “well done,” using temperatures between 135F/57C and 145F/63C, desirable results can usually be achieved within 48 hours, with the added application of the pinch test.

In the case of cured beef, the concept of rareness goes out the window, and, typically, temps between 140F/60C and 150F/65.5C create the highest quality product, meanwhile causing the least cellular damage and color degradation.

Pork-Fresh or Cured

Just like beef, in order to be safe (and to pasteurize), processing temps can start as low as 129F/54C. Temperatures can range up to as high as you want, but, to fully take advantage of the SV process, they rarely go above 150F/65.5C. Even though pork can be safe at 129F/54C, most people are much more familiar with, and prefer, the appearance of well done. Therefore, boneless pork is typically processed at temps starting at about 135F/57C . Cuts with a lot of bone may require an extra 5F to minimize “pink along the bone,” where penetration experiences greater resistance–processing at the lower temps may run the risk of pathogen free autolysis, which is what typically creates a sour, “off” odor, and even bag inflation.

Most pork cuts are then “reprocessed” via BBQ, smoker, oven, fryer, etc. The results still benefit from the SV processing, as most practitioners discover in short order.

That being said, tender cuts like chops, baby backs, and tenderloin achieve pasteurization @135F/57C  “Medium” within 4 hours. Tougher cuts like shoulder, leg, spareribs and belly achieve the pasteurized state at the same rate, but take longer to achieve tenderness, depending on the temperature used. @135F/57C , most cuts of pork will be tender after 24 hours, although many people go considerably longer, and hotter, to achieve the “pulled pork” result. Again, use the pinch test to refine results.

A word about fresh pork: Fortunately for us, our romantic notions about food safety have been dispelled, as a result of learning about SV. Not so for the public. If you plan to serve fresh pork “right out of the bag,” and you process lower than 145F/63C, you may find yourself making last minute adjustments to accommodate your guests.

Poultry

Poultry is a little bit less dense than beef and pork, and therefore slightly more susceptible to the presence of bacteria inside the meat itself, instead of just on the surface. So, in order to be safe (and to pasteurize), processing temps start at 132F/55.5C. Temperatures can range up to as high as you want, but, to fully take advantage of the SV process, they rarely go above 150F/65.5C. This should be starting to sound familiar, and that’s the great thing about pasteurization. It is basically circumstance and species independent. Even though poultry CAN be safe at 132F/55.5C, most people are much more familiar with, and prefer, the appearance of well done, with the occasional exception of duck breast. Therefore, poultry is typically processed at temps starting at about 135F/57C   . Chicken (and other poultry) are frequently “reprocessed” via BBQ, smoker, oven, fryer, etc. The results still benefit from the SV processing, as most practitioners discover in short order.

That being said, chicken achieves pasteurization @135F/57C  within 4 hours. Turkey takes longer, only because it is thicker, so, usually 6 to 8 hours becomes the guideline. Some people process drumsticks and thighs longer, or higher, to achieve desired results, but this is optional. Tenderness is rarely an issue with poultry, but, the pinch test can still be applied as desired.

 Lamb

Again, in order to be safe (and to pasteurize), processing temps start at 129F/54C. If there are bones still attached to the meat, I usually recommend 132F to compensate for the difference in thermal conductivity of bone vs meat. Temperatures can range up to as high as you want, but, to fully take advantage of the SV process, they rarely go above 150F/65.5C. The appearance of doneness that we refer to as “rare” is right there @129F/54C, and graduates to well done subjectively somewhere between 140F/60C and 150F/65.5C.

That being said, tender cuts racks and chops achieve pasteurization @129F/54C, “Rare” within 4 hours. Tougher cuts like leg and shoulder achieve the pasteurized state at almost the same rate (due to slight differences in thickness), but take longer to achieve tenderness, depending on the temperature used. @129F/54C, some cuts can take as long as 48 hours to become tender, although somewhere between 24 and 36 hours usually achieves excellent results. Again, use the added application of the pinch test.

Fish and Shellfish

There are many different models used for processing fish and shellfish via SV. Typically, pasteurization is not part of the paradigm, because the results seem “overcooked” by most people’s standards. Lower temperatures are used, lobster tails will cook in 30 minutes at 140F/60C or even below. Certain fish like halibut, sole, and salmon are frequently processed as low as 110F/43C, giving a unique result of raw appearance but cooked texture. Times are typically less than two hours, even for 3-4lb. whole fish.

We hope this was helpful.

Norm King.

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