Determining Fat Content of Arbitrary Meat with a Microwave

[geostriata]

There was a sale on untrimmed tri-tip ($5/lb) recently, so I tried to make snack sticks out of it. Despite it having a lot of extra fat, the end result was not good. There wasn't enough fat. As someone who's made a ton of sausages at this point, it was a bit disappointing that I still couldn't eyeball the ground meat for fat content. Determined to avoid this problem again, I set out to find a way to empirically determine the fat content of ground meat. At a minimum, this will be a useful sanity check when I'm trying new meat sources.

So I found this resource from the University of Pennsylvania and tried it out. With a little tweaking and extra derivations, I think I've got it dialed in for an easy check during sausage making. I'll share those results here.

Here's a summary of the approach:
1. Find out how long it takes your warmed microwave to evaporate all moisture from 20g of meat.
2. Prepare your sample meat by processing it into a pink blob (ensuring uniformity of fat and lean).
3. Tare a beaker (or pyrex container) on the scale. Weight out 20g of the pink meat into a beaker. Store the exact weight (e.g., 20.12g)
4. Cover with a napkin/paper towel and rubber band and weight that. (e.g., 23g)
5. Warm your microwave by nuking 250-500g of salt for 4 mins
6. Nuke the sample for your calibrated time in step #1.
7. Weight the result (e.g., 10g).
8. Using the weights from #3, #4, and #7 you can compute fat percentage.

Let's do it! First I started with store-bought ground beef.

They claimed it was 27% fat. Let's find out if that's true or not!

I then took a good amount and put it in the food processor. Since I'll be using some for calibration, I wanted a little extra.

This resulted in a pink blob, which was needed for a uniform sample of lean and fat.

I tared the empty beaker on the scale, and weighed out 20.39g of the pink meat.

I then put a rubber band and napkin on the top. As you're nuking the product, it'll splatter. We want that oil splatter to be shown in the final result, so we can't have it splattering outside the beaker.

The above process is the same for when we're doing an actual sample. For now, we're using this bit of meat to calibrate our Microwave. So I set the beaker aside for a moment...

I then filled a container with 250g of salt and put that in the center of the Microwave. I then turned the Microwave on full for 5 minutes. This warms up the Microwave and ensures a repeatable environment for the evaporation step.

Then I put the sample in the Microwave, along with the warm salt, and Microwaved it at intervals of 30 seconds and weighed the results very quickly, trying to minimize the time outside of the microwave:

Initial Weight	WeightwNapkin	1min	2min	2:30	3:00
20.06g	22.41	12.89	10.7	10.6	10.51

As you can see, it only lost less than a percent in the final 30 seconds (and it started to smell) and an exact 1% at 2:30. So I decided to call my Microwave calibration figure 2 minutes. Now since this taking it in and out of the microwave disrupts the measurements, I then ran two trials with new samples. (Two trials are good, because it's easy to have outlier results periodically with this approach).

W_initial (Initial Weight)	W_napkin (Weight w/ Napkin and band)	W_final (2min final weight)
20.23g	23.09g	11.03g
20.33g	23.26g	11.07g

Since the results are within 1% of each other, I know they are good. So I proceeded to find the moisture% of the sample. The formula for this is:

((W_initial - W_final - (W_napkin - W_initial)) / W-initial)*100 = %Moisture
So,
((20.23 - 11.03 - (23.09-20.23)) / (20.23))*100 = 59.96%
​

Now that we have the moisture content, we can determine the fat percentage, which is as follows:

100 - ((%Moisture * 1.27) + 1.1) = %fat
So,
100 - ((59.96 * 1.27) + 1.1) = 24.8% fat
​

So despite them advertising 27% fat, this sample is actually 24.8% fat.

Let's try another example!

Here we have my typical brisket point/flat combination. I find this usually gives a solid fat percentage. Just looking at the ground meat, what would you estimate the fat percentage to be?

I ran through the test and got the following.

W_initial	W_napkin	W_final (2min)	%Moisture	%Fat
20.16	22.99	11.22	58.38	24.75
20.55	23.45	10.84	61.36	21
20.28	23.07	11.32	57.94	25.31

As you can see, the middle trial was a bit of an outlier. It was more than 1% different with the first trial, so I ran a third trial and got better measurements (I think there was some oil splatter uncaught with the second trial, which affected the results). So I averaged trial #1 and #2 to determine that the brisket cuts were 25% fat.


Let's do another example for the Tri-Tip. The meat that didn't yield a good outcome for me.

Look at all that fat! I think it's misleading...

I ground the lean bits separately more coarse (because I like how the 'show meat' improves texture), but don't worry, we can still determine the fat content. We just need more samples. But first, consider asking yourself: What do you think the fat percentage of these two mixed together is?

I ran through the tests for both types of meat.

Type	W_initial	W_napkin	W_final (2min)	%Moisture	%Fat
Lean Tri-Tip #1	20.39	22.96	8.30	71.9	7.59
Lean Tri-Tip #2	20.06	22.06	7.78	71.19	8.49
Fatty Tri-Tip #1	20.18	23.00	11.92	54.9	29.17
Fatty Tri-Tip #2	20.29	23.22	12.08	54.9	29.17

So you can see the lean was, as expected, low fat (avg 8% fat). And the fattier bits were much higher fat (29.17% fat).

Now I can determine the mixed fat content by simply weighing all the lean ground, weighing all the fatty ground. I had 992.9g of the lean and 2101.8g of the fatty ground. So:

((W_lean * %fat_lean) + (W_fatty * %fat_fatty)) / (W_lean + W_fatty) = Fat%combined
So,
((992.9 * 0.08) + (2101.8 * 0.2917)) / (2108.8 + 992.9) = 22.3%
​

The tri-tip was 22.3% fat! This explains why my last batch of beef sticks were not good! In addition, I think the last tritip I used was a bit leaner, so I may have been making beef sticks at 20% fat or so. So nice to have a scientific explanation of this!

So, to make a batch out of this tri-tip, I simply dropped the amount of lean I used by half to get to my minimum fat content for beef sticks.

((W_lean * %fat_lean) + (W_fatty * %fat_fatty)) / (W_lean + W_fatty) = Fat%combined
So,
((496.45 * 0.08) + (2101.8 * 0.2917)) / (2108.8 + 496.45) = 25%​

Hope that helps! Even if you don't run this computation for yourself, it's good to see a variety of ground meat and their fat contents. Personally, I plan to run this test as a quick sanity check whenever I'm doing a batch. There are benefits to reliably having the same fat percentage between batches...

 

[tallbm]

There was a sale on untrimmed tri-tip ($5/lb) recently, so I tried to make snack sticks out of it. Despite it having a lot of extra fat, the end result was not good. There wasn't enough fat. As someone who's made a ton of sausages at this point, it was a bit disappointing that I still couldn't eyeball the ground meat for fat content. Determined to avoid this problem again, I set out to find a way to empirically determine the fat content of ground meat. At a minimum, this will be a useful sanity check when I'm trying new meat sources.

So I found this resource from the University of Pennsylvania and tried it out. With a little tweaking and extra derivations, I think I've got it dialed in for an easy check during sausage making. I'll share those results here.

Here's a summary of the approach:
1. Find out how long it takes your warmed microwave to evaporate all moisture from 20g of meat.
2. Prepare your sample meat by processing it into a pink blob (ensuring uniformity of fat and lean).
3. Tare a beaker (or pyrex container) on the scale. Weight out 20g of the pink meat into a beaker. Store the exact weight (e.g., 20.12g)
4. Cover with a napkin/paper towel and rubber band and weight that. (e.g., 23g)
5. Warm your microwave by nuking 250-500g of salt for 4 mins
6. Nuke the sample for your calibrated time in step #1.
7. Weight the result (e.g., 10g).
8. Using the weights from #3, #4, and #7 you can compute fat percentage.

Let's do it! First I started with store-bought ground beef.

View attachment 701580

They claimed it was 27% fat. Let's find out if that's true or not!

View attachment 701581

I then took a good amount and put it in the food processor. Since I'll be using some for calibration, I wanted a little extra.

View attachment 701582

This resulted in a pink blob, which was needed for a uniform sample of lean and fat.

View attachment 701583
I tared the empty beaker on the scale, and weighed out 20.39g of the pink meat.

View attachment 701584

I then put a rubber band and napkin on the top. As you're nuking the product, it'll splatter. We want that oil splatter to be shown in the final result, so we can't have it splattering outside the beaker.

The above process is the same for when we're doing an actual sample. For now, we're using this bit of meat to calibrate our Microwave. So I set the beaker aside for a moment...

View attachment 701586

I then filled a container with 250g of salt and put that in the center of the Microwave. I then turned the Microwave on full for 5 minutes. This warms up the Microwave and ensures a repeatable environment for the evaporation step.

Then I put the sample in the Microwave, along with the warm salt, and Microwaved it at intervals of 30 seconds and weighed the results very quickly, trying to minimize the time outside of the microwave:

Initial Weight	WeightwNapkin	1min	2min	2:30	3:00
20.06g	22.41	12.89	10.7	10.6	10.51

As you can see, it only lost less than a percent in the final 30 seconds (and it started to smell) and an exact 1% at 2:30. So I decided to call my Microwave calibration figure 2 minutes. Now since this taking it in and out of the microwave disrupts the measurements, I then ran two trials with new samples. (Two trials are good, because it's easy to have outlier results periodically with this approach).

W_initial (Initial Weight)	W_napkin (Weight w/ Napkin and band)	W_final (2min final weight)
20.23g	23.09g	11.03g
20.33g	23.26g	11.07g

Since the results are within 1% of each other, I know they are good. So I proceeded to find the moisture% of the sample. The formula for this is:

((W_initial - W_final - (W_napkin - W_initial)) / W-initial)*100 = %Moisture
So,
((20.23 - 11.03 - (23.09-20.23)) / (20.23))*100 = 59.96%
​

Now that we have the moisture content, we can determine the fat percentage, which is as follows:

100 - ((%Moisture * 1.27) + 1.1) = %fat
So,
100 - ((59.96 * 1.27) + 1.1) = 24.8% fat
​

So despite them advertising 27% fat, this sample is actually 24.8% fat.

Let's try another example!
View attachment 701588

Here we have my typical brisket point/flat combination. I find this usually gives a solid fat percentage. Just looking at the ground meat, what would you estimate the fat percentage to be?

I ran through the test and got the following.

W_initial	W_napkin	W_final (2min)	%Moisture	%Fat
20.16	22.99	11.22	58.38	24.75
20.55	23.45	10.84	61.36	21
20.28	23.07	11.32	57.94	25.31

As you can see, the middle trial was a bit of an outlier. It was more than 1% different with the first trial, so I ran a third trial and got better measurements (I think there was some oil splatter uncaught with the second trial, which affected the results). So I averaged trial #1 and #2 to determine that the brisket cuts were 25% fat.


Let's do another example for the Tri-Tip. The meat that didn't yield a good outcome for me.

View attachment 701589

Look at all that fat! I think it's misleading...

View attachment 701590

I ground the lean bits separately more coarse (because I like how the 'show meat' improves texture), but don't worry, we can still determine the fat content. We just need more samples. But first, consider asking yourself: What do you think the fat percentage of these two mixed together is?

I ran through the tests for both types of meat.

Type	W_initial	W_napkin	W_final (2min)	%Moisture	%Fat
Lean Tri-Tip #1	20.39	22.96	8.30	71.9	7.59
Lean Tri-Tip #2	20.06	22.06	7.78	71.19	8.49
Fatty Tri-Tip #1	20.18	23.00	11.92	54.9	29.17
Fatty Tri-Tip #2	20.29	23.22	12.08	54.9	29.17

So you can see the lean was, as expected, low fat (avg 8% fat). And the fattier bits were much higher fat (29.17% fat).

Now I can determine the mixed fat content by simply weighing all the lean ground, weighing all the fatty ground. I had 992.9g of the lean and 2101.8g of the fatty ground. So:

((W_lean * %fat_lean) + (W_fatty * %fat_fatty)) / (W_lean + W_fatty) = Fat%combined
So,
((992.9 * 0.08) + (2101.8 * 0.2917)) / (2108.8 + 992.9) = 22.3%
​

The tri-tip was 22.3% fat! This explains why my last batch of beef sticks were not good! In addition, I think the last tritip I used was a bit leaner, so I may have been making beef sticks at 20% fat or so. So nice to have a scientific explanation of this!

So, to make a batch out of this tri-tip, I simply dropped the amount of lean I used by half to get to my minimum fat content for beef sticks.

((W_lean * %fat_lean) + (W_fatty * %fat_fatty)) / (W_lean + W_fatty) = Fat%combined
So,
((496.45 * 0.08) + (2101.8 * 0.2917)) / (2108.8 + 496.45) = 25%​

Hope that helps! Even if you don't run this computation for yourself, it's good to see a variety of ground meat and their fat contents. Personally, I plan to run this test as a quick sanity check whenever I'm doing a batch. There are benefits to reliably having the same fat percentage between batches...

Wow this is super interesting for us data nerds hahaha.

I've never done snack sticks but I do a lot of sausage at 20% fat and it's always been good. Any chance that leaner tri-tip got you closer to 15% fat or do your snack sticks just need a lot more fat?

 

[geostriata]

Wow this is super interesting for us data nerds hahaha.

I've never done snack sticks but I do a lot of sausage at 20% fat and it's always been good. Any chance that leaner tri-tip got you closer to 15% fat or do your snack sticks just need a lot more fat?

Yeah, it could've been around 15% fat, but I'd like to think I would've noticed that...

My best guess is that it's the fact that I don't use binders in my snack sticks, and that I like them REALLY dry. I smoke them for ~27 hours at 140F (12hrs smoke, 15hrs cook) for a total of about 50% weight loss. I think that at this level of dryness, and without binders, having more fat is even more important. In addition, since I need these to be shelf stable, it's the weight loss that determines when the cook is done. Having increased lean not only impacts that, but also leads to a less consistent product. That's why I sought a means of measuring where I'm at.

Lastly, there's the taste. Too fatty and it tastes too sausage-like, without as much meat texture. I want my sticks to taste almost like jerky in beef stick form -- you need to feel the texture of the meat. Too dry, and it's sand after a 27hr cook. So where the range for sausage might be 20% - 30%, the range for my snack sticks might be more like 23-27%.

 

[tallbm]

Yeah, it could've been around 15% fat, but I'd like to think I would've noticed that...

My best guess is that it's the fact that I don't use binders in my snack sticks, and that I like them REALLY dry. I smoke them for ~27 hours at 140F (12hrs smoke, 15hrs cook) for a total of about 50% weight loss. I think that at this level of dryness, and without binders, having more fat is even more important. In addition, since I need these to be shelf stable, it's the weight loss that determines when the cook is done. Having increased lean not only impacts that, but also leads to a less consistent product. That's why I sought a means of measuring where I'm at.

Lastly, there's the taste. Too fatty and it tastes too sausage-like, without as much meat texture. I want my sticks to taste almost like jerky in beef stick form -- you need to feel the texture of the meat. Too dry, and it's sand after a 27hr cook. So where the range for sausage might be 20% - 30%, the range for my snack sticks might be more like 23-27%.

Ah good insight.

 

[geostriata]

One neat trick.

How might we use the above in the easiest fashion? To guide our sausage making, but without the trouble of having to use the food processor on a portion of the ground meat beforehand?

Here's how:

1. Mix you sausage meat as you normally would to protein extraction, adding water and ingredients.
2. Warm your Microwave for 5mins using the salt method.
3. Take 20g of the resulting product, and compute %Moisture
4. Then adjust for the addition of water (see below)

In the above batch, I used all of the ground meat in the initial post, minus 496g of the coarse lean (since that'd put avg fat percentage under 25%). So the 4482.65g of meat should have a fat% of around 25.

I then

• Added the 236.55g of ingredients and 785.9g of water to the meat, for a total weight of 5505.1g.
• Mixed the product as usual until sticky
• Took a 20g sample, warmed the microwave, and computed the %moisture as usual:

W_initial	W_napkin	W_final (2min)	%Moisture	%Fat (Incorrect)
20.13	22.93	10.84	60.05	22.62
20.11	22.91	11.04	59.03	23.94

This is expected. We've messed with our meat by adding ingredients and water. Protein extraction has occurred, binding that water and fat. Since the mix now holds more water, the prior formula "acts" like the fat has gone down (since lean holds more moisture).

In any case, the computation of the above %Moisture is still correct. So we can use that to determine %Moisture_meat (the moisture only of the meat product). That is computed with the following formula. So to recap:

• W_meat = 4482.65g (The meat product used in my mix)
• W_water = 741.43g (The water I added to help facilitate mixing)
• W_ingred = 236.55g (The spices I've added)
• %M_sample = 59.54 (From the post-mix sample, computed above)

The formula is:

100 * (((W_meat+W_water+W_ingred) * (%M_sample / 100) - W_water) / W_meat) = %M_meat
So,
100 * (((4482.65 + 741.43 + 236.55) * 0.5954 - 741.43) / 4482.65) = 55.99%
​

With the %moisture of the actual meat, we can then use the standard formula to determine the %fat of the actual meat:

100 - ((%M_meat * 1.27) + 1.1) = %Fat_meat
So,
100 - ((55.99 * 1.27) + 1.1) = 27.79%
​

So you can see the %fat on my mix is good! What the above formula does is compensate for the added water. This is very close to my predicted 25%.

Using this approach, you can mix as usual and do a quick little sanity check at the end. Doing an emergency adjustment and re-mixing a bit if you're way off.

 

[SmokinEdge]

now just go make sausage. It’s certainly not rocket science Sheldon.

 

[DougE]

now just go make sausage. It’s certainly not rocket science Sheldon.

Never needed to go to this extent thus far, and my sausages come out fine, so I'll just keep on keeping on.

 

[tallbm]

Most of my sausage is made from wild game where there is little to no fat so get or save pure fat and can easily get my % or very close to the ball park. 4 pounds pure ground meat 1 pound fat for 5 pounds of sausage. Not everyone had this luxury but I've had good luck with just grinding brisket and grinding pork butts. I never get little lean ones.

I find all these numbers and findings to be cool to have in the back pocket though.

 

[geostriata]

Never needed to go to this extent thus far, and my sausages come out fine, so I'll just keep on keeping on.

Yeah, all my sausage seem to come out fine as well. It's just the beef sticks that seem picky about fat content. I'm not at all saying this is necessary, just putting it here in case it's useful for troubleshooting or consistency.

now just go make sausage. It’s certainly not rocket science Sheldon.

Lol, I've still got 40lbs of sausage in the freezer from SausageFest. I think I'm good on sausages for a while, but I did just finish up the last of my beef sticks, hence this thread.

I suppose it is a bit academic, but I do think it's useful if you're really trying to get a specific fat % number. Or if, for whatever reason, you're buying the store-bought stuff (as you can't trust their percentages)

I get the "it's not rocket science" sentiment a lot, but I don't really buy it. The science of what we're doing with these meat products is fascinating! The curing process, Iron binding with myoglobin, the drying process, etc... There's a lot of depth it can be taken to, and I think it's fun and beneficial to go there.

 

[SmokinEdge]

Yeah, all my sausage seem to come out fine as well. It's just the beef sticks that seem picky about fat content. I'm not at all saying this is necessary, just putting it here in case it's useful for troubleshooting or consistency.


Lol, I've still got 40lbs of sausage in the freezer from SausageFest. I think I'm good on sausages for a while, but I did just finish up the last of my beef sticks, hence this thread.

I suppose it is a bit academic, but I do think it's useful if you're really trying to get a specific fat % number. Or if, for whatever reason, you're buying the store-bought stuff (as you can't trust their percentages)

I get the "it's not rocket science" sentiment a lot, but I don't really buy it. The science of what we're doing with these meat products is fascinating! The curing process, Iron binding with myoglobin, the drying process, etc... There's a lot of depth it can be taken to, and I think it's fun and beneficial to go there.

Yup. Experience gives you a “eyeball” that’s when the magic will happen. Over thinking will lead you down a rabbit hole and you may never enjoy success. Let the process be. Much like all of bbq. Just my advice to you.

 

[Up_In_Smoke]

In science, we don't think.

Seriously, that was a pretty cool experiment you did there.

 

[geostriata]

Yup. Experience gives you a “eyeball” that’s when the magic will happen. Over thinking will lead you down a rabbit hole and you may never enjoy success. Let the process be. Much like all of bbq. Just my advice to you.

I get that you have your preferred way of doing things, and I support that. You should do what works for you.

For me, the opposite of your advice has been true. My experience shows that "eyeballing" leads to inconsistent results. I've only had the success I've enjoyed so far by thinking through what is happening, and taking the time needed to understand what is going on. That's what I'm doing in this thread, and I believe that doing so will result in even more consistency moving forward.

“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.” - Lord Kelvin​

 

[Dave in AZ]

G geostriata Love this! Knowledge presses forward by inquisitive minds who question accepted things, look for ways to verify. I would rather be a Lord Kelvin or Tesla, investigating the world, than incurious. Good job, thanks for taking the time and posting your interesting results! Some folks may not be interested, but they probably didn't have chemistry sets as kids! ;)

At the least, this is a way for folks who haven't developed an eye for fat content, to calibrate their guesses and firm up their guesstimation experience.

 

[Up_In_Smoke]

G geostriata Love this! Knowledge presses forward by inquisitive minds who question accepted things, look for ways to verify. I would rather be a Lord Kelvin or Tesla, investigating the world, than incurious. Good job, thanks for taking the time and posting your interesting results! Some folks may not be interested, but they probably didn't have chemistry sets as kids! ;)

At the least, this is a way for folks who haven't developed an eye for fat content, to calibrate their guesses and firm up their guesstimation experience.

I had a Gilbert Chem Lab when I was about 7 or 8 years old.
More than once, I got questioned on why there were chemical stains on my ceiling
and why things went BOOM sometimes. :)

 

[geostriata]

G geostriata Love this! Knowledge presses forward by inquisitive minds who question accepted things, look for ways to verify. I would rather be a Lord Kelvin or Tesla, investigating the world, than incurious. Good job, thanks for taking the time and posting your interesting results! Some folks may not be interested, but they probably didn't have chemistry sets as kids! ;)

At the least, this is a way for folks who haven't developed an eye for fat content, to calibrate their guesses and firm up their guesstimation experience.

Thanks D Dave in AZ ! I'm glad to hear you found it interesting, that means a lot!

And yeah, I do think it'll help me get better at eyeballing fat content now. :)

 

[geostriata]

I had a Gilbert Chem Lab when I was about 7 or 8 years old.
More than once, I got questioned on why there were chemical stains on my ceiling
and why things went BOOM sometimes. :)

Haha! I got a stain on my wall from my set, but it was low to the ground, so I put a poster over it. My parents eyed new the poster at floor level and gave me the stink-eye: "Why is that poster basically on the ground? Ok, what are you hiding?"

I could still tinker with it, but not in my room. I think so they could keep an eye on me, and ensure I don't set the house on fire, lol.

 

[Dave in AZ]

Lol... I got caught labeling my product c2H50H... I didn't know my Dad knew alcohol! That shut me down for a while... I guess there are only so many things you can do with a reflux condenser, he was suspicious already!

 

[geostriata]

Lol... I got caught labeling my product c2H50H... I didn't know my Dad knew alcohol! That shut me down for a while... I guess there are only so many things you can do with a reflux condenser, he was suspicious already!

Haha, brilliant! Man, if I knew how to make alcohol at a young age, I would've gotten in so much trouble...

 

[SmokinEdge]

“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.” - Lord Kelvin

Ok, LOL.

 

[DougE]

“When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.” - Lord Kelvin

On the contrary. My knowledge is quite satisfactory to me without having to express it in raw numbers to everyone else.

I have a number of recipes I have done so many times that I know, by eye, or feel, how much of this or that to add. May not be a useful method to share the recipe with others, but it's quite sufficient and satisfactory for my own uses.