Grassfed Beef Suet is an Excellent Source of Stearic Acid

Last summer when I first started experimenting with The Croissant Diet I had breakfast at a friend’s place. He was on The Carnivore diet and had been inspired by Paul Saladino to eat fried beef suet with his eggs. I had a plate of eggs and beef suet and the suet was… waxy. Much more so than normal beef fat. My only prior experience with eating suet was my grandmothers suet pudding, which she made every Christmas. Maybe she had been onto something! I wasn’t ready to shout out the stearic acid content of beef suet to the world because I wanted more evidence first. Frustratingly, I couldn’t find a single paper that listed the fat composition of beef suet.

Something that is made very clear by this Cordain paper is that the fat composition of different tissues varies markedly within the same animal. For instance, the saturated fat content of wild elk bone marrow is 20% whereas the saturated fat content of wild elk backfat (subcutaneous) is 65%!

In the original Croissant Diet specification I listed wild elk backfat as one of the best sources of stearic acid as a result of this paper. Obviously it was a little tongue-in-cheek, I wasn’t expecting people to go out and start hunting elk for the backfat, but I think it’s an interesting historical perspective that shows the normal upper range of saturated fat in traditional human foods.

I’ve always been frustrated that this paper doesn’t report on the fat composition of abdominal fat or kidney fat – the layer of fat that surrounds the internal organs. This is the layer of fat that in a cow is called beef suet. Nor could I find the fat composition of kidney fat in any other paper, until Stefano Shiavi tweeted this:

Finally, some data! The link to the paper is here.

If this data is true, beef kidney fat would be a true stearic acid superfood, up there with cocoa butter, my stearic acid enhanced butteroil and wild elk backfat. Not only was the beef suet high in saturated fat in general but the majority of the saturated fat was from stearic acid. There are not many foods for which this is true. But I only had the one data point and this is a Turkish paper and it could be due to something specific about the breeds or feeds being used in Turkey. I had reason to be suspicious: the paper reported the saturated fat content of intermuscular fat to be 56%, whereas the USDA reports that the saturated fat from the lean part of beef cuts to be around 37-40%, whether from grain finished or grass finished beef.

Math Stuff

I wanted to test the ratios to reconfirm that beef suet was as high in long chain saturated fat as was being reported but I didn’t have the extra cash to send it in for testing and I wanted to create a repeatable test that I could use for future experiments. The basic concept was this: using the leftover 50:50 stearic acid : palmitic acid (100% long chain saturated fat) I had from the original Croissant Diet test and Macadamia Nut oil (14% SatFat, 3-4% PUFA, 80% MUFA), which they sell at the local Wegmans, I could make a series of test blocks at different ratios as an example of fats that were 60:40 SFA:MUFA, 50:50, 40:60, etc. Then I could compare the firmness of those blocks to different rendered beef fats. The PUFA content would be low and similar to that in beef fat. It would give me a baseline for how firm different fats should be at different ratios of SFA:MUFA.

Collecting and Rendering Fats

I sourced some grass finished beef suet from Windsong farm in Burdett, NY. Wegmans carries grain-finished (presumably) beef suet in the dog food section, so I got some of that. Lastly, I found a piece of beef chuck that hard a large enough piece of fat in it that I could trim it out and render the fat down.

The first step is to render the fats, which is easy if you know how. I know from experience that rendering works faster the smaller the size of the fat is. So I coarsely chopped the fats then pulsed them in my food processor.

Chopping up the large block of suet.
Then I pulse it in the food processor. If the little pieces flow freely without sticking to each other – kind of like grated Parmesan cheese – it’s a good sign you have a very firm fat. If the chopping forms a paste, like if you were chopping up warm cheddar cheese, you’ll get a softer fat.

The rendering process is not unlike slow cooking bacon until the fat cooks out and the strips get crispy. I put the chopped fat into a saucepan and add a little water in the beginning to get everything steaming. I put the pot on an induction burner set to around 350 and cover it with a lid. Within minutes, fat will start to cook out from the meat, just like bacon. Soon the whole thing will be at a rolling boil.

As the rendering process continues, the solid pieces will get smaller and their color will turn darker. The boiling will mostly stop and the amount of steam produced will be much less. It is time to strain the suet.

Straining the beef suet.
Tada! Rendered beef suet. It gets very hard as it cools. This is the grassfed suet, it had a much yellower color compared to grain finished, presumably due to higher beta-carotene content.

Testing!

Once I had rendered my three samples: grassfed beef suet, grain finished beef suet and chuck fat, it was time to start testing them. And I mean immediately because I was excited. I knew from a kitchen “experiment” from a few years back that you can dump 20 quarts of 230 degree lard over your whole arm without any serious repercussions so I wasn’t shy about dipping my fingers into the hot grease.

It’s February and I keep my house pretty cool – around 60F (that’s 16C for you Canadians, which is how I categorize people who use the metric system (Kidding!! Geeze! I get that most of the world uses the metric system (‘Merica!))) – and at that temperature the grassfed suet would wax up fairly readily on my fingertip. The grain finished beef suet would wax up a little around the edges and might have eventually waxed up on my fingertip but it was definitely a lot slower. The chuck fat didn’t wax up at all.

The grassfed beef suet readily got waxy on my fingertip at 60F.
The chuck fat stayed liquid!

I poured samples of my three fats into cupcake tins and started the long wait for them to fully set. From experience I knew they wouldn’t be fully set until the next day.

In the meantime I went about making my test blocks – one each at 40%, 50% and 60% SatFat. Assuming 14% SatFat in the Macadamia Nut oil, the blends looked like this (I made 40g test blocks):

SatFat PercentageStearic/Palmitic AcidMacadamia Oil
40%12g28g
50%17g23g
60%22g18g

The next morning there were a couple problems. The first was that the dramatically different melting points between the stearic acid triglycerides and the macadamia nut oil triglycerides had caused the test samples to crystallize while cooling. They weren’t homogenous, you could see and feel the crystals, just like in ghee. Still, they clearly each had differing levels of hardness and therefore IMO some idea about what I was looking for as a reference.

The bigger problem was that the beef suet samples were rock hard. Brittle, homogenous, rock hard blocks. How do you determine if one rock hard lump is harder than another rock hard lump? The 60% SatFat test block was also a rock hard lump.

So I made some new samples. I made two new samples from each rendered suet, diluted one with 25% Macadamia Nut Oil and the other with 50%. So for each suet sample I had 100% suet, 75% suet and 50% suet with the balance as Macadamia Nut Oil. And I waited overnight. Again. While I waited I spent a lot of time poking at the samples. What would happen?!

1) Reference block, 60% saturated. Hard, but somewhat crumbly due to the crystal structure. 2) Reference block, 50% saturated, still hard but gives when squeezed. 3) Reference block, 40% saturated. Firm rather than hard. A bit like butter at a cool room temperature. 4) Grassfed beef suet. Very hard. 5) 75% grassfed beef suet, 25% macadamia nut oil. Still quite hard. It can be crushed between the fingers but it takes quite a bit of force. Similar to block 1. You can see that this sample cracked along straight lines rather than some of the other samples that broke up in a “stickier” way. 6) 50% grassfed beef suet, 50% macadamia nut oil. Still firm. Somewhat comparable to block 3. 7) 75% grain finished beef suet, 25% macadamia nut oil. Firm but yielding under pressure. Similar to blocks 3 and 6. 8) 50% grain finished beef suet and 50% macadamia nut oil. Easily the softest sample. Creamy. 9) The grain finished beef chuck tallow. Firm but yielding. Similar to 3, 6 and 7. Not shown: 100% grain finished suet. Hard.

How is it For Cooking?

This is important, of course. Is it waxy? How is the flavor? I did what I knew I had to do which was to immediately fry up a mountain of fish and chips.

It was really quite good. I almost finished it. Personal note: I like cocktail sauce.

Conclusions

Grassfed beef suet is VERY saturated. Vastly more saturated than fat from the chuck and significantly more so than grain finished suet. I can’t tell using this technique whether the thing that makes the grassfed suet harder than the grainfed suet is higher saturated fat or lower polyunsaturated fat, but either way, I’d call it a win for the grassfed.

The USDA database says most grain finished beef fat from the chuck is around 43% saturated and 16% stearic acid. The chuck fat sample certainly seems in line with that. Sample 6 (50:50 grassfet suet : macadamia oil) is, if anything, slightly less firm than the beef chuck fat. If we assume sample 6 is 40% saturated and that macadamia oil is 14% saturated and calculate backwards, it suggests that the grassfed suet is about 66% saturated. 66% saturated fat is the exact number from the elk and antelope subcutaneous fat in the Cordain paper, so that is in the expected range of saturated fat from ruminant fat stores. In the Turkish paper, stearic acid represented 56% of the saturated fat from beef suet, suggesting a total of as much as 37% stearic acid in the grassfed beef suet. I’m not sure the 37% number is accurate, but I am sure that grassfed beef suet is an excellent source of highly saturated fat and specifically stearic acid.

I also conclude that it’s excellent for deep frying.

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