Sous Vide Warm Aging Revisited

Six years ago I blogged for the first time about a technique that I called “warm aging”. Aging is a technique that is used to improve the texture of meat and sometimes also to give it more flavor by the activity of enzymes that are naturally present in the meat. You have probably heard of “dry aged” beef. This means that the beef has been aged for a long time (3 to 6 weeks or even longer) and allowed to gently dry. Dry aged beef is expensive because drying means losing weight, and because the outer edges have to be trimmed. Dry aging makes the meat more tender and, if aged for along enough, develops the flavor. An alternative is wet aging, which is to vacuum seal the meat and then store it at refrigerator temperature for 3 weeks or so. This has the same tenderizing effect as dry aging but without the weight loss (and without the flavor component).

The enzymes that do the tenderizing act very slowly at typical refigerator temperatures of 4C/39F. At higher temperatures they work more quickly, and so the effect of weeks of aging can be achieved in hours. In Modernist Cuisine it is suggested to ‘cook’ beef first at the temperature at which calpains are the most active (39C/103F) and then at the temperature at which cathepsins are most active (49C/120F), without becoming very specific of how to go about this. There is food safety to consider, so you shouldn’t do this for longer than 4 hours. I tried it for 2 hours and was impressed by the result, and have used this technique often ever since. I am pleased to see that many have picked up on it, and that the term “warm aging” that I came up with seems to have stuck. (I think that is more appropriate than calling this ‘cooking’, since at such low temperatures the meat stays quite raw.) There have been some that claim that the side-by-side experiment that I performed was inaccurate, because I compared beef that was first warm aged for 2 hours and then cooked for 2 hours at 55C/131F with beef that was just cooked for 2 hours at 55C/131F. It was argued that the warm aged meat was more tender because it had been cooked for a longer time, and so I should have compared 4 hours at 55C/131F with 2 hours of warm aging and 2 hours at 55C/131F.

Although I believe that both cases are not fully comparable, there is some merit in the fact that if you have 4 hours to cook beef, it makes the most sense to find out what will give the better result: all 4 hours at 55C/131F, or half at warm aging and half at cooking. But still I thought the difference between cooking at 55C/131F for 2 or 4 hours would be too large (because in my opinion no actual cooking occurs at warm aging temperatures), and so I came up with an alternative experiment and that is to use flat iron steak/blade steak.

This is a cut of beef that, provided it is butchered in such a way that the tough sinew that runs through the center is removed, can even be just pan fried. Personally I prefer it with 8 to 12 hours of sous vide cooking at 55C/131F, as otherwise I think can be too tough. (This does depend on the source of the meat, for example grain-fed can be more tender than grass-fed.) Due to the longer cooking time I could come up with an experiment that had less of a difference in cooking time, but with the same overall time in the sous-vide.

I took the nice piece of blade steak above, and cut it in two pieces. Do you notice the nice marbling?

They were both seasoned with salt and freshly ground black pepper, and vacuum sealed.

To avoid food safety issues, I scalded both pieces in boiling water for 20 seconds after vacuum sealing. (In the experiment six years ago I seared the beef before vacuum sealing, but since then I have developed the scaling technique that is a lot safer.) Especially 39C/103F is a temperature that pathogens thrive at, so it this is a good precaution.

Even though this step wasn’t really necessary for food safety reasons for the piece to be cooked at 55C/131F, I scalded both pieces to keep the experiment on equal footing.

Then I conducted the experiment as follows:

  • One piece was first warm aged for 2 hours at 39C/103F, then warm aged for 1 hour at 49C/120F, and then cooked for 5 hours at 55C/131F.
  • The other piece was cooked for 8 hours at 55C/131F.

My thinking was as follows: because of the scalding step I was confident enough to warm age for 3 hours. As both types of enzymes are active at 39C/103F and only the cathepsins are still active at 49C/120F (and more active than at 39C/103F), I thought it made sense to use a longer time at 39C/103F to get the best of my 3 hours. I suppose I could do further experiments to optimize this further.

After this process I patted both pieces dry with paper towels…

…and seared them quickly over high heat in clarified butter.

The warm aged piece is on the left, the other on the right. The difference was clearly visible and even more clear to taste. I knew which was which, but my guinea pig Kees did not. He thought (and I agreed) that the piece that I later revealed to him as the warm aged piece was more juicy and had a better texture. The other piece was softer, but a bit too soft. The tenderizing that happens at 55C/131F is a different type of tenderizing than what happens by the enzymes at lower temperatures. The warm aged piece was not more tender than the piece without warm aging, but the texture was definitely better.

If you still don’t believe me, try it for yourself. You will be glad that you did!


25 thoughts on “Sous Vide Warm Aging Revisited

  1. Hello Stefan,
    I have been following your blog for several years.
    Inspired by a Bulgarian colleague I started using sous vide in 2015.
    Your “warm aging” has been fully adapted in our way of cooking.
    We use it for the Iron steak as you used for this experiment, but also for bavette, rib lappen (as used in your original post) and longhaas.
    We modified the times a little, to 1.5hr 39.5 degC, 1.5hr 49.5degC. and 4 hr 54degC.
    I noticed that keeping the meat vacuum bagged in the zero degrees compartment of our fridge it will age further (we tend to buy big portions from a whole sale store and make small portions before the sous vide).

    What is your reason of keeping it longer on 39 degC than 49?

    Thank your for sharing all your nice recipes, we learned a lot from you.


    Liked by 1 person

    1. Hi Renzo, I thought I explained the longer time at 39C in the post, but I guess I have to check that. The reason is that both types of enzymes work well at 39C, whereas at 49C one works better and the other does not work at all anymore.
      Thanks for the nice message! Hope to ‘see’ you again soon.


  2. Hallo Stefan,

    Deinen Foodblog verfolge ich schon von Anfang an. Vielen Dank dafür.

    Zu diesem Blog: ich verwende Vakuumbeutel der verschiedensten Hersteller und kann mich erinnern das nicht alle 100Grad Wassertemperatur vertragen? Deswegen flamme ich immer schon das Fleisch vorm vacuumieren mit einem Gasbrenner ab. Danach gehts dann in den Beutel Gab bis jetzt keinerlei Probleme.

    Liebe Grüße und weiter so!

    Dieter Achtel


    Liked by 1 person

    1. Hi Dieter, thanks for your nice message. I can read German very well, but I hope it’s ok to reply in English.
      For this preparation it is ok to torch the meat before vacuum sealing. However if you are going to cook for more than 8 hours at a temperature below 60C, your method is not failsafe against the bad smell that can be caused by lactobacillus. This is because lactobacillus is ‘everywhere’ and can contaminate the meat after you torch it.
      Regarding vacuum bags that can’t take 100 degrees: please make sure that the bags are suitable for cooking. It is not healthy to cook food for a long time in a bag that leaches chemicals and then eat such food often.
      Thanks and hope to ‘see’ you again soon!


  3. Always helpful. Thank you for your dedication.

    I built my first sous vide controller with a PID, a relay, and a cigar box attached to a hot plate 15 years ago. Since reading your post 6 years ago I’ve always warm aged – it the gift that is beef since no other meats have the different enzymes.

    I appreciate your diligence here but the outcome was certain for me.

    Liked by 1 person

  4. Hi Stefan,

    Hope you’re still safe!
    Whit all that extra time at home it’s time to experiment 😉
    I hav got this nice dry aged steak and wanted to try your warm aging method as well. I’m a little confused about the time frame of the last 55* step. In your first, old blog, you did about 1h 39*, 1h 49* and 2,5h 55*.
    In your revision you do 1h 39*, 2h 49* and 5!h 55*. The only other difference is the boiled water scalding in the beginning, instead of the short searing.
    Would a shorter 55* time harm any result?

    Best regards and stay safe!


    1. Hi Frans,
      The 5 hours is only to make it comparable to the 8 hours total time of the other steak in the experiment. The only requirement is to cook it long enough to pasteurize at 55C.
      Besides your question, if the steak is already dry aged, warm ageing will have less of an effect.
      Good luck!


      1. Ok, you did the first one also with a dry aged I believe. What would be your suggestion in this case? Same scheme, but how many hours to pasteurize?



    1. If the steak is already dry aged, leave out the warm aging and do it at your temperature of preferred doneness. That could be 55 but also 52 or 57, depending on your preference and how fatty the steak is. Pasteurizing is not strictly necessary for steak, so the time mostly depends on the thickness.


      1. Thank you, but it already happened…;)
        No worries, I did the warm aging as well. It turned out pretty good.
        Still very juicy.
        Next time I will do without.
        My next try with warm aging I will try a plain riblap.
        Let you know.
        BTW, just finished your perfect turbot with asparagus; very yummy!

        Liked by 1 person

  5. Tried the rib lap with your warm aging technique. Amazing and perfect steak. Juicy and tender.
    I had worse real steaks before…
    Thanks for trying out and sharing your experiments!
    Best regards,

    Liked by 1 person

  6. Thanks for the excellent blog Stefan! Quick question here. Can we do warm aging and then store the bags with the ready to finish in the pan meat in the fridge for next day’s Barbie? Good day to you mate!

    Liked by 1 person

    1. You can if you warm age and then increase the temperature to 55C/131F and hold long enough to pasteurize.
      Warm aging without the pasteurization step would be risky, because you have held the meat at a temperature at which bacteria thrive without killing them afterwards.


  7. So I’ve done this several times now (love it! every steak I’ve done has been so much beefier than without!) but one problem I run into is not having time to actually do it on a week night because of work. My assumption is, though confirmation would be appreciated, is that if I finish all the steps through cooking it to my desired doneness I can put it in the fridge and sear the next day. Any thought Stefan?

    Liked by 1 person

  8. Hi Stefan, Is it safe to seal an entrecote, dip in boiling water, cook at 39.5C for 1 hour, cook at 49.5C for 1 hour and then grill in a hot pan? Forgot the dipping yesterday and a sous vide experienced friend was really worried about my health and strongly adviced me to skip the 49.5C and cook at 55C for 1 hour. So I did but found the meat a bit overcooked.


    1. Yes with the dipping it is safer. If the entrecote is 2 cm or less, I would advise to chill it before grilling as otherwise it may still be overcooked, depending on how long you grill it.


  9. As you also seem to be a fan of dry brining (1% 24hrs 35°F), what do you think of the theory that once brined, the scalding step is no longer necessary?


    1. I don’t expect it to work, because the lactobacillus is on the surface and putting salt on the surface doesn’t solve the problem. With a higher amount of salt it probably would work, but then you’d br curing instead of brining and it would become very salty.


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