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Collagen conversion equivalency

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    Collagen conversion equivalency

    We know that we can make food safe by pasteurizing and that 5 seconds at 165F is close to 5 minutes at 150F and same as 2.5 hours at 135F. This is incredibly useful info for SV processes and the usda curves for this are searchable and in kenj’s food lab book also.



    On the other hand, I haven’t seen a curve for collagen conversion to gelatin. It would be useful to know how long this takes at various temperatures because it is a function of temp and time.

    For instance, you can fully tenderize tough cuts in tens of minutes in a pressure cooker because you are running well above boiling.

    In classical braised recipes it takes hours and temp is in the 175-200 range.

    In classic low and slow BBQ, you cook until around 203F. The final temp isn’t the factor here l, but the time it spends in the stall and beyond on its way there. (That why the final temp isn’t directly related to tenderness as it is the sum of time and temp).

    For SV it would be nice to have a curve that tells you this equivalency fo converting collagen to gelatin with time and temp.

    Does anyone one have a graph or data spanning the range of time and temperature for tenderization (collagen conversion)? I thought I saw a partial graph on a serious eats page but it didn’t go very low in temperature.

    this is important primarily because if you cook above 130-140 you start to dry out the actual muscle fibers, but how much time will it take to equivalently tenderize at those low temps? I had thought this an unsolvable problem but SV pulled chuck got me thinking about it again.

    edit. Found the curve on serious eats page but it doesn’t go to extreme enough temperatures or times.
    http://www.seriouseats.com/2011/03/h...-food-lab.html
    Last edited by Polarbear777; February 11, 2018, 09:27 PM.

    #2
    I had probably seen that graph and forgotten. I follow the experiences of other pit folk and myself. You may find some of the observations in these notes useful. https://www.evernote.com/l/AKIlTFr77..._MJOc6dUsrYfbw

    Comment


      #3
      All three of those words in the same title? Very impressive.

      Comment


      • Donw
        Donw commented
        Editing a comment
        Sounds like a show title from The Big Bang Theory. 👍🏻

      #4
      That might be a little tougher to quantify since Log reduction only tells you in theory what percentage of Microbes you will eliminate of what's there.

      In other words, 1 Log removes 90% of what is present, be it 100 or 1,000,000,000. That is why trying to just barely kill what you think is there is dangerous if you don't know the actual load.

      Removing 90% of 1 billion leaves quite a bit more than removing 90% of 100.

      So how can each piece of meat be quantified? I can see a general scale, but I have sous vide a cured chunk of meat at 131 and ended up with PLENTY fluid in the bag. Sooner or later that water is coming out.

      Comment


      • Polarbear777
        Polarbear777 commented
        Editing a comment
        Is your post saying you can’t equivalently pasteurize at lower temperatures either?

        We don’t have a curve for tenderness vs time vs temp so that’s what I’m looking for.

      • Jerod Broussard
        Jerod Broussard commented
        Editing a comment
        Polarbear777 No, you can quantify it, but Log reduction isn't an exact number at any temperature. It's just giving you a percent reduction of what is available. SeriousEats does a good test on brisket, but even with that you'll see it isn't as simple as just temp and time, since different temps give different textures, regardless of time.

      • Polarbear777
        Polarbear777 commented
        Editing a comment
        True because as temperature goes up muscle fibers contract and that gets combined with the tenderness we get. If meat done-ness and connective tissue breakdown are independent enough, we could find a way to set them to our liking separately, since done ness stops with temp, then we adjust the other with time. Limit on time is practicality and things that don’t die or stop acting above 131F.

      #5
      I've thought about a curve like that, but I worry that it would depend on the cut of meat, i.e, on the amount of connective tissue that requires conversion.

      Comment


      • Polarbear777
        Polarbear777 commented
        Editing a comment
        Shorter answer (see below for verbose): if you know how long your target takes to get tender at the higher temp, you could convert via the curve to a lower temp and longer time.

      #6
      I’m sure it does depend on meat and thickness. But the conversion rate for the same amount is time over temp so if you had a curve where the data was derived from the same amount then you would know how to convert any recipe from one temperature to another by adding/subtracting time. Would be very useful for translating classic braises over to pressure cooker as well.

      Kenj’s curve is a starting point but there’s not really enough data points to help extrapolating to temp/time extremes. Would take some time to fill in such a curve which is why I was hoping someone had done it.

      Same rate idea as the pasteurization (the target matters). You may be pasteurizing at the same rate at 131F for both chicken and beef, but the potential salmonella load is higher in chicken so you may need a 7 log reduction instead of 6 so you have to go longer (4.5 hours) But you are still able to determine the conversion to another temperature by changing the time (15 sec at 165).. of course that is assuming this is the temp where you need the effect, not necessarily just the surface so you have to add more time per thickness for the heat to travel.

      Comment


        #7
        Ah! Good idea. So you're looking for a one-parameter model for a curve with a fixed shape where the parameter lets you scale up or down to fit a known temp-duration. Hmmm. Intriguing. Let me think about that a bit more.

        [Edited] Well, the regression of log(hours) on log(temp) is very, very linear. So I suppose you could use those coefficients and re-create a curve with the same shape as Kenji's but with a different "fitting" point that depends on your known preferred texture to extrapolate to a new set of times and temperatures. Hmmm. I think I'll try that sometime to see whether the prediction works out.
        Last edited by RobertC; February 11, 2018, 10:30 PM.

        Comment


        • RobertC
          RobertC commented
          Editing a comment
          So, for example, you could test to see whether that modeled relationship works at different times/temperatures for these: https://www.chefsteps.com/activities...perature-guide

        • Polarbear777
          Polarbear777 commented
          Editing a comment
          We could combine Kenjis data with the data you posted and EdFs notes, extrapolate and test the end points for validity (still subjective and the tenderness measured by a different person for almost all points). I may end up doing that, since nobody else apparently has looked at constructing the curve rigorously.

        • RobertC
          RobertC commented
          Editing a comment
          Polarbear777 So, if you had been doing 1-1/2" pork steaks @ 140 for 30 hours, and if the time-temp model looked like Kenji's brisket, you ought to be able to get a similar "tenderness" result from 21 hours @ 145F or 15 hours @ 150F.

        #8
        You guys are waaay more into science than I am! ;-)

        Comment


        • FireMan
          FireMan commented
          Editing a comment
          Yoh! 👍

        #9
        Maybe Meathead could pose this question directly to Kenji, as he may have secret back door access only open to best selling, published authors . Perhaps Chef Kenji and his staff are working on the more extreme parameters and answers you seek... Or you could post this same question on Serious Eats. I guess you could email the deans office at Culinary Institute of America and see if they have the answers? Other than that, I can' think of any smarter folks...

        Comment


        • FireMan
          FireMan commented
          Editing a comment
          Those were my thoughts exactly. What did I just say?

        • EdF
          EdF commented
          Editing a comment
          That you're one of the smarter people!

        #10
        Polarbear777 , EdF KevinG It's really not all that complicated. All we're saying is that an increase of ~1% in temperature (whether in Fahrenheit or Celsius) reduces hot tub time by, ballpark, ~10%. That's just a ballpark, but it gives you a rough rule of thumb to know how much "trade-off" there is between time and temperature. Alternatively, for every 1% you lower the temperature, you'll need to increase time by ballpark 10%. Sous vide isn't all that demanding in terms of timing so getting into the ballpark can be handy.

        Comment

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