Nitrite levels: Calculations and Measurements

[PolishDeli]

So I’ve been annoyed at there being two different, but both “correct,” methods of calculating Nitrite levels in meat. i.e., USDA Method1: %-pick up (or %-injection), and USDA Method2: Equilibrium. To get a desired amount of NaNO2 into a ham, each method calls for a very different amount of Cure#1 to be used. Which method is best for the home hobbyist?

To satisfy my curiosity, I used the thanksgiving ham as an excuse to run some measurements, and invested the big bucks in a Nitrite test kit (API Aquarium Water Test Kit for $7.50).

In summary, I used Method 1 (recipe is below), and found the NaNO2 concentration in the ham to be on target. I did not test Method 2, so I’m not claiming that it is wrong. But I did convince myself that injection + immersion for 1.5-2 days/pound is not nearly enough time for equilibrium concentrations of NaNO2 to be reached between the ham and brine.

I went full geek on this science experiment, so I’d be happy to post a complete “lab report,” if anyone is interested.

------------

Recipe:
60°SAL brine, sugar at 3% of salt by weight, 150ppm NaNO2 according to method 1, injection at 10% of green ham weight + immersion for 1.7 days per pound of green weight.

Meat: 7.1kg (15.6 lb)
Salt: 1422g
Cure#1: 182g
Sugar: 43g
Water: 7.6L (2.0 gal)
Injection: 0.71L

Start date: 10/24/18 18:30
End date: 11/20/18 15:30

Target NaNO2 concentration: 150ppm
Measured NaNO2 concentration: 164ppm
Measured NaNO2 concentration after smoking+baking: 138ppm

Overall goodness of the ham: All 20 guests enjoyed it, and no one got sick.

 

[daveomak]

You can save some time and money...
For a 10% injection on a 15.6 # ham... (7,082 grams)

3% x 7082 = 212 g salt
1% x 7082 = 70 g sugar
0.25% x 7082 = 17.7 g cure#1

Dissolve the above into 710 g injection liquid...

Inject the entire amount of the above into the ham, preferably at 1.5" spacing and in 6-7 days you have a perfectly cured ham....

 

[atomicsmoke]

Indeed 1.5-2 days is not enough in an equilibrium cure. We usualy cure for 7-10 days for a slab of bacon. Ham 2-3 weeks depending on the side/shape. Problem with the 10% pickup method is that is not a consistent process. Depends on the amount of curing liquid, size, shape of the meat. It works for commercial processors who have established processes in place. You were dead on this time. Will you be next time when you do say a belly? Hard to say.

 

[zwiller]

Wish you tested method 2. Impressed how well #1 went. I don't think equilibrium is ever really reached/world is not perfect. Not easy for us OCDers.

If you want some other experiments with those trips: Test Dave's method (no immersion) and I'd like to see how much nitrite is lost with curing in an acidic liquid. IE curing a ham with apple juice.

 

[indaswamp]

With the equilibrium method, you are calculating the ppm of cure in the final mass of both the water (liquid portion of the brine) and the meat. The amount of cure needed should be more than that used in the injection method.

With the equilibrium method, the high concentration of cure in the brine falls as the cure travels into the meat, eventually equalizing if the meat is left long enough in the brine. The end ppm in both the water and meat is the target ppm for the meat.

With the injection method, there is no brine liquid to calculate for, thus since all the cure is injected into the meat at once, you just have to wait for the cure to equalize within the meat.

Hope this helps...

 

[browneyesvictim]

Congrats on doing your math so you KNOW. I know for a fact DaveO's method is so simple and effective for injection method. I totally agree for larger items like ham injection is a must for a full cure and is better suited for method #1. Yet Pops brine has also long been proven to be safe at the proscribed soak times for the type of meat plus injection of anything over 2" for method #2. To me each have their application I prefer for the type of meat.

But I cant help but point out you are missing Method #3 using a dry brine method- Cure calculator, tenderquick etc...

 

[PolishDeli]

I’m on the same page with all the comments, thanks all. My grasp of the calculations and their inherent assumptions is pretty good (thanks to reading this forum), but I wanted to test those assumptions. I’m not saying one recipe is better than any other; just reporting that this process worked, and that the measurements are in agreement with the math. It was a fun side project, and I might run some more tests with other recipes.

Anyway, here are some more details:

-Green weight: 7.1kg (15.6 lb)
-Pumped weight: 7.6 kg kg (16.8 lb). So the target of 10% is actually 7.7% due to leakage. Had I bagged it at this point (DaveO’s method) instead of immersing it, the ham would have been closer to 115ppm.
-Cured weight: 7.9kg (17.4 pounds). Therefore the total weight gain was 11% (pump + pickup). So the max NaNO2 the ham could have had was 173ppm, unless there was movement toward equilibrium (complete equilibrium would have been 775ppm).

I tested the NaNO2 concentration is two ways.
First: The NaNO2 concentration of the brine before and after curing. Any movement toward equilibrium would result in a decreased concentration of NaNO2 in the brine after curing. After 27 days of curing, the NaNO2 concentration was unchanged, at 1500ppm.

Second: The NaNO2 levels in the meat were measured. To do this, a piece of cured meat was cut from the center of the ham. It was weighed and put it in a blender with a known amount of water. After measuring the NaNO2 concentration of this solution, the amount of NaNO2 in the meat was easily calculated. This test was repeated after smoking+baking.