Effects of Purifying | New Testing

Welcome back everyone. It's been a hot minute for me, life has been busy, and writing blogs is not at the top of my to do list. Even though I enjoy them, the subject is something that I need to be crazy passionate about to write more than 3,000 words about it. But fear not because tallow is easily one that I am very passionate about. 

We have done some more up to date testing that has some more accurate data to analyze. We have partnered with Kai Tallow(https://www.kaitallow.com/Tallow) to get more testing done. Gabi Stonys has always had a passion for high quality traditionally rendered tallow, so we were excited at the prospect of working with her and getting her perspective with her science background on the differences between the samples. She is also writing in her own words a blog on the results(We Lab Tested Dry vs. Wet Rendered Tallow – Here Are the Results – Kai Tallow, LLC). Be sure to follow her on Instagram (Instagrahttps://www.instagram.com/kaitallow/m) as she talks a lot on dry rendering there and shares much info.

 If you have been around for a while, then you may be familiar with our tallow testing from 2023. We sent two samples of tallow in for testing (a dry rendered sample/1x purified sample). If you haven't read that blog post, you may want to so you can be caught up on this one click here to read-Is Purifying Tallow Necessary?

Today we are going over these new set of labs that were conducted in May 2025, and June 2025. Totaling 3 tests to compare and analyze.

Inaccurate Data

The original lab testing in 2023 did reveal that the fatty acids were altered from the dry render sample. Albeit not a huge change-but they either increased or decreased from the original dry rendered samples. There were definitely some discrepancies that could have affected the results, and we know this because these new set of tests we did showed the opposite effect on most of the fatty acids. We felt to get a better more accurate view of the changes that were occurring we needed to do more testing to fully understand the effects. This time comparing a dry rendered tallow to TWO 3x purified samples-all from the same cow/same batch. This means these tests are extremely accurate in showing the changes in the fatty acid profile.

One thing I've realized from doing all these tests, is the fatty acids vary enormously from one section of the cow to the next, regardless of if it's all from the same cow. The hardness, and type of fat greatly determines the fatty acid values, and my realization is that the first tests I did weren't accurate enough. It wasn't enough that the fat was from the same cow, it NEEDED to be from the same batch of rendered tallow. At the time I didn't realize that the fatty acids could vary so drastically from batch to batch even from the same cow! It was my first time doing lab testing after all. Which is why those results weren't as accurate as these new tests. It wasn't enough that it was from one box of the same fat from one cow. It had to be from the same 1 batch of rendered tallow that way the fatty acids were the same throughout to give an accurate depiction of what the changes were. This time around we MADE SURE we didn't make that mistake again. Which is why the results are interesting!

 

What We know For Sure 

What we do know for sure without a doubt regardless of the discrepancies from the very first test-is that the fatty acids do indeed change. 

It's been interesting to see reactions/reception to the labs, many have dismissed them as a meaningless lab test that prove nothing, and they won't believe it until a large-scale study will be done. But there will likely never be a large-scale study done on the effects of purifying tallow, and that's because researchers don't care about miniscule things like that. Purifying is a fairly new practice and is not the traditional way tallow is rendered. The only ones overly concerned about that are people like me who are small business owners and use tallow for skincare, and don't believe the lie that has been perpetuated that purifying tallow is required. Another reason is the businesses who purify would never do testing to see how purifying is affecting tallow because they don't want to know/don't care-its unimportant to them. They want to continue purifying so they likely won't pay for lab testing to see if there are consequences to doing it. Which is fine! Thats their own personal choice. I am not here to say one is better than the other or go to battle on the hill of dry rendering. 

For me personally the 2023 lab testing just confirmed to me that it was unnecessary to continue purifying, which I was doing up until that first set of lab tests. They assured me that tallow isn't dirty or has impurities that need washing away and that I can traditionally dry render tallow that isn't stinky and can keep all of its benefits intact. 

The purpose of this whole experiment was to show that PURIFYING WASNT REQUIRED OR EVEN NECESSARY. Many have believed that they had to purify likely due to one YouTube video back in 2019 to use it for skincare-which wasn't true and STILL leaves a lot of people confused. To date there is zero evidence to support that purifying doesn't alter the fatty acids or degrade the tallow in anyway. In other words, there is no supporting evidence that shows that purifying is completely fine and free of consequence when it comes to the finished quality.

The Smoke Point Myth

The idea that there is no evidence that purifying affects the nutritional profile of tallow because the smoke point of tallow is 350-400 degrees and until you hit 350-400 degrees the fatty acids are fine is completely false. 350-400 degrees is the smoke point in which tallow completely oxidizes and is unsafe to use in any application- BUT the degradation of fatty acids and nutrients happens LONG before that. Smoke point vs. altering the fatty acids/nutritional profile are two very different numbers and points. Hitting smoke point= ruined/destroyed fat. Damaging/altering the fatty acids happens well under 350 degrees. This is another example of the misinformation that gets pushed around and confuses people even more.

Its interesting that those who are very dismissive of our labs on the topic of purifying, but yet they always fail to show any evidence to support why they think purifying is fine and doesn't affect anything. Thats because there is no evidence that shows that it doesn't affect the tallow-there is however evidence that shows purifying does change the fatty acid profile which is essentially degradation and likely leads to less stability and effects the tallow. We will link other studies which indicate this at the bottom of this blog. People can make claims and sound very convincing, but it means nothing without proof.

Third Round of Testing | A Tale of 3 labs

*We should also add that this tallow was dry rendered initially, then purified which likely doesn't have any bearing on the results. The fat still needs to be cooked with water and salt several times regardless of if it was done that first render. The outcome is the same. Starting the rendering process with water or no water has no effect on the results. How could it? The tests HAD to be done this way, as the fatty acids vary drastically from one area to the next on the cow. So, to ensure that the fatty acids would accurately reflect any changes it was best to dry render the main batch then draw the samples from that and purify them. This way it would ensure we could get a good reading of the exact changes to the fatty acids.

Testing methods:

All three samples were from the same cow, same batch of tallow, from strictly kidney/suet fat. Cows are fully grassfed and finished and from a private cattle ranch in Southern Arizona.

All samples were from 1 large batch that was Dry rendered from raw suet at 190-200 degrees over the course of a full day(10-12hrs). Then three 50g sample sizes were removed for testing. The first sample tested was the control and just dry rendered. The second sample) was taken from same dry rendered batch and purified with equal portions purified water and two tablespoons of Kosher salt and purified to 200 degrees for 30 mins no less than 3 times. Then was followed up with a dry render to remove any remaining water. The third sample was taken from the original dry rendered batch and purified with same amounts of water and salt and heated to 200 degrees for no less than 5 hours each no less than 3 times. Totally 15 hours of purification time. Then followed up with a dry render. 

All samples were sent to the same lab Food and Safety net services located in Houston Texas for fatty acid profile testing.

Results

Fatty Acid	Dry Render 1st sample	3x Purified (2nd sample)	3x Purified (3rd sample)
Myristic Acid	2.83	2.82	2.78
Myristoleic	.14	.14	.12
Palmitic	24.30	24.31	25.42
Palmitoleic	1.50	1.49	.83
Margaric	1.11	1.11	1.10
Stearic	31.47	31.58	33.79
Oleic	25.03	24.99	23.74
Trans Elaidic	8.35	8.35	8.07
Linoleic	3.79	3.74	2.81
Alpha linolenic	.23	.22	.13
Arachidic	.24	.24	.25
Eicosenic	.18	.19	.17
Total Fat	99.94	99.94	100.00
Monounsaturated	26.85	26.81	24.90
Omega 3	.23	.22	.13
Omega 6	3.84	3.79	2.89
Omega 9	.18	.19	22.87
Polyunsaturated	4.10	4.04	3.02
Saturated Fat	60.59	60.69	63.98
Trans Fat	8.40	8.39	8.11

The results are reflected in the comparison chart above and the changes noted below it are from the dry render control and the third test with the longer purification times. The 2^nd test(column 2) reflects that no significant changes were noted, small changes were noted in the linoleic, monounsaturated fat, Oleic, Polyunsaturated and Omega 6 values.

Totals from dry render control sample and 3rd sample (1 & 3^rd column tests)

Myristic Acid- decreased .05g

Myristoleic Acid decreased .02g

Pentadecanoic acid decreased .02g

Palmitic increased 1.12g

Palmitoleic decreased .67g

Margaric decreased .01g

Stearic acid increased 2.32g

Oleic Acid decreased 1.29g

Trans Eladic decreased .28

Linoleic decreased .28g

Alpha Linolenic decreased .10g

Arachidic increased .01

Eicosenic decreased .01g

Total Fat Increased .06g

Monounsaturated fat decreased 1.95

Omega 3 decreased .10g

Omega 6 decreased .95g

Omega 9 increased 22.69g

Polyunsaturated fat decreased 1.08g

Saturated Fat increased 3.39

Trans fat decreased .29g

The third set of tests with longer purification times showed much more significant changes with the Omega 9s having the most drastic changes followed by the Omega 6s. This shows a more destabilizing effect on the smaller fatty acids, and a decrease in all the Omegas, linoleic, linolenic, oleic and polyunsaturated fats. Which is not surprising as they are more sensitive to temperature changes. But the 127% actually corrected that's a12000% increase in the Omega 9 fatty acids is a bit concerning. This drastically throws the ratio off. 

The Conjugated linoleic acid falls under the Omega 6/Polyunsaturated fat category, which both decreased in the third tests by a good amount. That shows the CLA is affected by purifying. 

Something interesting to note is that the Stearic acid and Palmitic acid values increased, which Gabi from Kai Tallow had a really good reason as to why that could have happened that I didn't even think about. She mentioned that the process of hydrolysis could have increased the free stearic acid meaning it would show an increase on the test. That process is when the heat and water break down the triglycerides which encapsulate the fatty acids like stearic and palmitic and release more free stearic acids. It separates the fats from the glycerol's which is like the backbone of the fatty acid.

 This could explain why that happened. This process can also occur with Oleic acid, and when oleic acid goes through hydrolysis it can actually break down and convert into stearic acid. Which is crazy! But this actually lines up with the results of these tests. As the Oleic acid decreased and the stearic acid increased. Hydrolysis can typically require a catalyst like nickel to help push the process and or a salt like potassium hydroxide. In the case of these purifying samples both of those were present. Stainless steel typically contains a small % of Nickel and adding salt & water can drive this process. Of course these are my personal theories. There is no way to know 100%.

Also lets look at the Palmitoleic acid which is a Omega-7 monounsaturated fat. This fat decreased in 3rd sample by almost half from the dry rendered sample. Palmitoleic acid is present in human tissue meaning it's one of the fatty acids that we have in our skin barrier. Its known for promoting wound healing, and strengthening the skin barrier. It's unfortunate a large amount of it gets lost during purifying. 

. The second sample showed surprisingly that minimal change in the fatty acids can be achieved by very short purification times and at lower temperatures. Even in the Omega fatty acids. Which is actually really good news, and it confirms that you can actually purify without affecting the fatty acids too much. As long as all the water is fully removed from the tallow.

Conclusion

We can conclude from these labs that purifying does alter the fatty acids, and the temps it does that are much lower than what many people think. Now take all this information at face value and know there will always need to be more testing to know this without a doubt. We did our best to ensure everything was accurate as far as the temperatures, measurements and that the tallow samples were all from the same cow and same batch of kidney fat. Which we think gave pretty accurate results.

 If all this is true than it totally contradicts what was originally believed about tallows fatty acid profiles being completely stable. They aren't and in fact they can quite easily be affected/changed by water and heat. It seems many people know this but purifying is the norm these days when it comes to rendering tallow. 

Despite what some may think I am not here to convince you to choose one or the other in regard to wet or dry rendering, rather my motivations have mainly been to understand what purifying is doing to the finished tallow, and if it is removing some of the wonderful benefits of using it. If you choose to purify that's more than fine, and from our second sample we can see that minimal purifying really doesn't affect the tallow negatively. You just have to make sure you do a final dry render and that all the water is boiled off to prevent bacterial growth.

We're going to link other studies that you might find useful on the topic of fatty acids and heat and temperature.

(PDF) Study of the Stability of Beef Tallow at High Temperatures and Comparison with Other Fatty Materials -

This study looked at the stability of several tallow samples and the results may surprise you, some tallow samples showed lower oxidative stability than sunflower oil, here is an excerpt:

"Conclusions Even though beef tallow’s inherent stability indicated that it should be highly stable to oxidation, the majority of these samples exhibited a comparable or lower stability than SHO and several even lower than S"

We hope this information was helpful, and we will be doing a longer YouTube Video going more Indepth about these lab tests results. We'll link that here as soon as its ready.

Please leave thoughts in the comments below we check these not as often as we should, but I will be keeping my eye out for comments to respond to.