Tuesday, January 22, 2013

Fat and Offal

 Guest Post by Stu Crawford

I've recently found myself spending a lot of time processing dead animals, and I've been learning things that I definitely should have already known.  I thought that some of you might be interested, so I took a few pictures and wrote up an article.

One of the dead animals was a deer that I shot, the other was a goat that I was given to use for an anatomy class with the elementary school in town.  So, I canned, dried, and froze a whole lot of meat.  I also had a lot of non-meat items to deal with.  Some things, like spleens, are inherently tasty and require no special attention.  Other things require a bit more knowledge and effort to transform them into a useable product.

I ended up with 20 lb of extra fat that I had to do something with - the deer was pretty fat, and the goat was obese.  And when I dissected the goat with the elementary class, we opened up its digestive track to look at all its stomachs.  This reminded me of all the tasty tripe that I can't buy in Haida Gwaii, so I decided to try processing my own.

There is a lot of information on the internet, but some things are underrepresented.  There was very little reliable information about rendering fat, and none about processing tripe.  So, I've documented my efforts.  I've been contemplating putting together a webpage for ages, and someday I might actually get around to doing it, but until then, here's my article.


There are a variety of different types of fat, which I will divide into three categories.  

The hardest fat is the stuff around the kidneys, which is called suet if it is from a cow, and leaf lard if it is from a pig.  Cow suet is rendered into tallow for making candles and soap, and used for deep frying.  Kidney fat has a higher smoke point than other animal fats, about 200°C, which is really hot.  Suet and leaf lard are often the preferred fats for a lot of baking.  The pot on the rear right burner has goat suet.

Various kinds of fat ready to be rendered: goat omentum (left), goat suet (rear right), and deer back fat (front right). S Crawford Photo

The second most preferred fat for cooking is the back fat.  I would expand this to include any subcutaneous or intramuscular fat.  This is the bacon fat, and of course it is pretty tasty.  The pot on the front right burner has deer back fat.

The other significant fat is the abdominal fat, which is sometimes called caul fat.  This fat isn't loose in the abdominal cavity, it is contained within a fatty membrane called the omentum, which drapes over the organs.  This is the least preferred fat for cooking, although some people suggest wrapping a roast in the omentum before baking it, which sounds delicious, because it's basically a giant fat blanket.  The pot on the left has the omentum fat from the goat.

In case you are wondering, that's about 80,000 calories of food cooking on the stove.  It's not every day that you can cook a month's worth of food all at once.

I rendered the fat in water, which meant that I didn't have to watch it as closely to prevent it from burning.  I added 2 cups water per lb of fat, and then let it simmer for a long time.  The pots with 3 lbs of fat in them took 5 or 6 hours, and the pot with 6 lbs of fat took 9 hours.  Eventually all the water boils off and you are left with little deep-fried pieces floating in pure fat.

Early stages. S Crawford Photo
Final stages. S Crawford Photo
The picture on the left is after it has been boiling for a few hours.  The fat chunks are starting to break down, but there's still water in the pot, so the temperature is being held at right around 100°C.  The picture on the right is after about 8 hours.  The water has all boiled off, so it looks more like a sizzling deep fryer than a boiling pot of soup, and the temperature is now starting to increase.  I had best results when I boiled it until it hit 125°C.
Rendered fat cooling in jars. S Crawford Photo
The yield was roughly one pint per pound of fat, but it depended on the type of fat.  The back fat had the lowest yield, probably because it had more impurities.  I ended up with a little over a gallon and a half of product.  The jars on the left are still warm and liquid, they will turn white when they cool.  The jars on the far right are the deer back fat, which ended up being slightly darker in color.

Ground deer suet. S Crawford Photo
I didn't render all of my fat, I also ground some of the suet for use in baking.  The bowl on the left is goat suet, the bowl on the right is deer suet.  I froze the chunks first so they could go through the meat grinder.  I baked the biscuits using the ground deer suet instead of lard.  They were delicious!  I don't know how different they would have been if I had used the rendered suet instead of the ground stuff, it's something that I'll have to test out.  I also need to compare the fats from different locations on the animal, and from different species.  Lots of eating to do. 
Suet biscuits. S Crawford Photo.


Towel Trip. S Crawford photo
The first stomach is the rumen, which is the picture on the left.  As you can see, it is substantially larger than all the other stomachs put together.  It is also called towel tripe, but I have never actually seen it for sale.  Apparently it doesn't taste as good as the other kinds.  The second stomach is the reticulum, which is called honeycomb tripe.  This is my favorite type of tripe.  There is a common dish at Chinese restaurants called gnau tou, which is honeycomb tripe in a dark marinade with ginger and some other spices.  It is delicious, and I wish I could get a recipe for it.  The third stomach is the omasum, which is also called leaf tripe or book tripe.  It is hard to tell from the photo, but those aren't just folds in the stomach, they are actual partitions that stick into the space.  This is the type of tripe that is used for gnau ba yip, another common dish in Chinese restaurants.  It is usually only very mildly spiced, and is pure white.  The fourth stomach is the abomasum, which is the true stomach.  I have never seen this for sale.  It has a very different texture, because it is lined with glandular tissue (it is the only stomach that secretes digestive juices).  Apparently it is called reed tripe, and isn't very highly regarded.
Honeycomb (left 2), leaf  (center) and reed (right) tripe. S Crawford photo.
Obviously it is important to wash the tripe very thoroughly.  It actually washes easier than you might expect, and you can see that my tripe is all quite clean, no specks of green stuff.  However, you also have to remove the lining.  Tripe that you buy in the store is bright white.  The brown lining has been removed to reveal the off-white colored tissue underneath, and that is chemically bleached to make it pure white.  I don't really care about bleaching it, but it does seem like I should remove the lining.  Unfortunately, there is very little information available on how to do this yourself.  A few people suggested boiling it for a long time, which I did.

Boiled trip. S Crawford photo.
This is the boiled tripe.  As you can see, it shrank.  However, the lining has not fallen off.  After hours of tedious picking, I succeeded in pealing half of the omasum (front right).  The reticulum has resisted all attempts at pealing.  Obviously there is some trick that I'm missing.  I'm currently trying an acid bath.  Any suggestions would be welcome.

Stu Crawford is a Canadian ethnoecologist, lichenologist, and forager who lives on Haida Gwaii.
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  1. Stu- This is great research and info- thanks for sharing. I'm similarly trying to figure out how to deal with an abundance of fat from a very plump deer. My question is how do you deal with the rapid coagulation of the fat (high melt/solification point) when cooking with it? I blend some into my burger grind but am not wild about the waxy feel of the fat as it hardens on my lips and coats my mouth, so I hesitate to use it as a general cooking fat (like bacon grease). I've been thinking of trying to blend it with an oil to lower the melt point and hopefully make it more versatile for eating, or alternatively, mess around with the soap and candle angles. Maybe with your baked goods the coagulated texture is not an issue. Curious if you have any thoughts on these properties of the fat.
    best, Matt

    1. Matt - That's a good question. I've heard several other people complain about the unpleasant mouth-feel when they add deer fat to their ground meat. But I always add some fat, and I've never noticed it. I use backfat, though, and I wonder if other people sometimes use abdominal fat, which has a higher melting point?

      I did notice a bit of the bad mouth-feel when baking with ground suet, but only after the baked goods were cold. But they are so good fresh out of the oven, it was an easy problem to solve - just eat them all while they are still hot.

      I don't think that it's a problem when using the rendered fat for frying. So far I've only used it a couple times, but I haven't noticed the mouth sensation at all, and neither did my wife, who is much more fussy than me about that sort of thing. Tallow is the traditional fat used for deep-frying French fries, and I've never read any complaints about that either. Perhaps the rendering process solves the problem by breaking down the fat particles into smaller bits.

      Blending the tallow with oil is an interesting thought, but I'm not sure if it would have the desired effect. I suspect that you'd end up with the undesirable characteristics of both fats - the low smoke point of vegetable oil, and the high melting point of tallow.

      If you do decide to experiment with using rendered deer fat for frying, let me know how it works for you. I'll report back when I have more experience with it.

      ~ Stu

  2. Hi Abe, neat entry! We've done a bit of rendering ourselves, including beef, deer and lamb tallow. My favorite way to prep the fat for rendering is to grind it first (I highly recommend the "chop-rite" hand crank grinders over the cheap Corona and electric I once had!). I seem to get a much better recovery rate this way. The "cracklins" or leftover pressings are my dog's favorite treats, though that may be because I'm too squeamish to eat them myself.

    Sheep/lamb tallow was commonly used as a rust preventative for tools before the widespread use of petroleum products, and I've been using deer tallow for this now which works quite well. Just keep a tin on the workbench with a rag for spreading a thin layer on the tool. Also use it on wood handles and such.

    My wife has made soap with the beef and lamb tallow. Haven't tried the lamb soap yet, but the beef tallow soap was great. Thus far we've just used commercial lye, but I'm planning to make our own with wood ash as well.

    We found that 50/50 beeswax/tallow is an excellent combination for drip free candles (ours worked best with the stiffer square cross section wicks).

  3. Wow, very interesting. My friend does all her cooking in lard and I'm interested, but not a hunter. I do, however, have a hunting brother in law who I hope doesn't think I'm crazy when I go asking him for the fat from his next kill. Thanks much.

  4. Thanks for this entry and for Matt's question! There are now a few articles online explaining how to render but since mine still is solidifying quite quickly after removing from the stove it wasn't clear to me whether there was something I was missing. So this article that shows a picture of your jars and explains that back vs. stomach fat will behave differently was very helpful - I mixed mine all together so that's probably why. I am still using the product for cooking and probably because of the small quantity it's not bad. Also my desire to use the fat is probably making up for some of the undesirable characteristics...next time I might separate the fats, but then again I don't know if I would ever get around to using the stomach fat.

    Finally, I didn't know the spleen tasted good, I'll be doing more homework before my next hunt to make sure I use more of the offal! Cheers.

  5. Nice post! You have provided good information about fat extraction and how to convert it into edible oil. I have never tried out tripe before. Is it used for eating or just kept for something else?

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