I have a bunch of oxtails I've been braising for hours in an adobo sauce and they remain awfully tough. What I'd love to see happen is for that abundant connective tissue to melt away and coat each fiber of meat with its succulent juices, but that collagen just does not want to budge.

This makes me wonder what is causing the conversion to fail (or just take so long). I'm sure the fact that we're dealing with oxtail is a factor--and older piece of meat simply is more tightly bound. But I suspect there may be more going on here as well. For example, the braising liquid is relatively acidic--would the pH of the medium affect the conversion rate? Or water hardness, perhaps? I've checked the collagen references in "On Food and Cooking" but didn't find anything that seemed relevant.

So, generally speaking what factors will affect the rate and effectiveness of collagen to gelatin conversion?

  • This is odd. In winter, I often braise oxtail in red wine and after 3-4 hours the meat just falls off the bone. Commented Jan 12, 2013 at 12:55
  • That's been my experience as well--which is why I was a bit surprised when it wasn't going here, and suspected the chemistry of the braising medium.
    – Ray
    Commented Jan 12, 2013 at 13:05

2 Answers 2


I was unable to find information that might tell what happened to your dish, but found some extremely interesting and detailed sources of information on collagen and gelatin which I think are worth sharing.

I did find that the pH is unlikely to be the major contributing factor, as there are both acid and alkaline processes for gelatin formation--see the Science of Cooking, Gelatin.co.za, and Hydrolization references below.

Since you have read On Food and Cooking, you almost certainly already know the basics of what affects the conversion rate. To paraphrase one of the articles, it is a high energy stochastic process so:

  • Gelatin conversion is time and temperature dependent, with higher temperaturs permitting faster conversion
  • Requires the presence of water, as it is a hydrolization of the denaturing collagen proteins

Of course, it sounds like by braising for hours, you have met these basic criteria.

Here are some sources I found:

At this point--I stopped, as I have learned more about gelatin than I need to know as a cook!

  • Very interesting references. That will give me some reading for a while. Thanks. Commented Jan 12, 2013 at 17:14

You wrote that you were braising in adobo sauce for hours.

As SAJ14SAJ (whose name is a pain to type on my tablet) well said-gelatin conversion requires water, heat, and time. I know that you had heat but I'm not sure you have enough water or time.

Adobo sauce tends to be very thick. I would recommend diluting it with water (or stock), letting the meat cook to your liking and then reducing the braising liquid afterwards if necessary.

You said "hours" how many hours has it been going? I will let really tough meat simmer for at least four hours- one hour if in a pressure cooker.

  • Ah, I should have had more detail there--the sauce was purposely made thin so that it could later reduce. Also it had been going at a low simmer for about 5 hours at the time of writing.
    – Ray
    Commented Jan 12, 2013 at 20:05

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