Kent wrote:
> Thanks Reg, for the above post. I've been trying to straighten out the math.
> I am going to buy the book from Morton.
>
> Prague #1 and #2 have 1 ounce nitrite/lb salt. Morton's TC has .08 ounce/lb.
> Prague #1 and #2 have .0625 ounces nitrite/ounce salt, or 6.25%. Morton's TC
> has .005 oz. nitrite/ounce salt, or .5%.
>
> Prague #1 and #2 have 00015625 ounce nitrite/25 lb meat, or 156.25 parts per
> million, by weight. Morton's TC has .0000125 ounce/25lb meat or 12.5 parts
> per million by weight.
Right on all counts.
> If you add salt to either prague powder you come up with the ppm ratios
> you mention. TC has a lower relative concentration of nitrite because that
> much more salt is added into the cure, with a ratio of nitrite to salt one
> tenth that of prague powder.
Key point there. TQ contains much more salt, so in order to get
above 100 PPM in nitrite you'd have to add so much TQ that it
wouldn't be edible. Too salty. That's why I use prague #1 instead
of TQ. It's much more versatile.
The above begs some important questions. It should be asked
therefore, what is a reasonable minimum level of nitrite? How
much do you need to achieve adequate preservation, and does
TQ suffice in achieving this?
Unfortunately, all of the coverage in the US code (CFR)
has to do with *maximum* allowable levels. There's no
mention of minimums. If you're goal is to use the proper
amount of nitrites this you'll have to consult other
sources.
If you're interested in investigating it there are some solid
mathematical models out there. There's a free program called
Pathogen Modeling Program that employs these models to predict
various pathogen growth outcomes.
PMP is available he
http://ars.usda.gov/Services/docs.htm?docid=6784
It's based on the following models, some of which include
sodium nitrite as an input parameter:
- Growth models> for Aeromonas hydrophila, Bacillus cereus, Clostridium
perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella,
Shigella flexneri, Staphylococcus aureus, and Yersinia enterocolitica.
- Time-to-Toxigenesis model for Clostridium botulinum on fish.
- Time-to-Turbidity models for Clostridium botulinum.
- Non-thermal inactivation/survival models for Escherichia coli O157:H7,
Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus.
- Thermal inactivation models for Clostridium botulinum, *Escherichia
coli O157:H7 and Listeria monocytogenes.
- Gamma Irradiation models for Salmonella typhimurium, Escherichia
coli O157:H7 and "Normal" flora in meats.
- Cooling/Growth models for Clostridium botulinum and Clostridium
perfringens.
After creating many models and experimenting with the nitrite
parameters you'll see that nitrite begins to have a measurable
effect on botulinum at around 40-50 PPM. This effect is
magnified by a factor of three by about 100 PPM or so. However
with salmonella, nitrite doesn't begin to have a significant
impact until it's above about 100 PPM.
When you see these effects in action, the industry standard
of around 150 PPM makes very good sense.
> All of this works with direct injection or arterial curing because all of
> the nitrate in your cure ends up in what you are curing.
>
> It strikes me that all of this falls apart when you brine. The amount of
> nitrite in the brine depends on the total volume of brine you are using with
> a given concentration, the weight of the meat in the brine, and how much of
> the nitrite and nitrate gets into the meat during the brining period. Each
> type of meat would have a different absorptive ratio depending on species,
> fat and muscle characteristics and so forth.
Yes, the above applies to "direct addition" only, i.e. adding
it directly into a mix of ground meat.
The key to understanding how to achieve predictable and
consistant nitrite levels through brining is in understanding
equilibrium of the solutes (nitrites, salt, sugar)
When you first put the meat in the brine, the meat will
contain 0% nitrites, and the solution will contain some
non-zero amount. X percent.
After a long enough period, the meat and the brine will both
contain the same level of nitrites. They will have achieved
equilibrium, and the nitrite level in the brine will be
diminished somewhat because of the water that naturally occurs
in meat. The actual level will be the above mentioned X, minus
some amount, which will vary based on the ratio of brine to meat.
So, in order to achieve the desired predictability you can't
use "short" brining methods, you have to keep it in the brine
for the full amount of time required for equilibrium (which
can be accelerated by injecting, obviously). That's
point #1.
Point #2 is that you have to take the water contained in
the meat into account in your calculations. Here's a sample
calculation that takes that factor into account.
As an example, we'll use an 8 pound brisket which is
being made into pastrami. For water percentage of the meat
we'll use 65% by weight. Salt content of the brine is 3%
by weight. Sugar is 2% by weight. Target nitrite level
will be 150 PPM.
First, calculate the amount of salt to add.
1 gallon water = 8.3 lbs
Weight of water in meat = 0.65 x 8 = 5.2 lbs
3 gallons of water = 25 lbs (rounded off)
Weight of brine water + water in meat = 25 + 5.2 = 30.2 lbs
30.2 x 3% = 0.91 lbs salt
30.2 x 2% = 0.60 lbs sugar
Knowing the weight of the brine and the meat you
can calculate the amount of curing salts required.
Weight of meat = 8 lbs
Total weight of brine = 30.2 + 0.91 + 0.60 = 31.71 lbs
Lbs of nitrite = 150 PPM x (total brine weight + meat weight)
--------------------------------------------
1,000,000
Lbs of nitrite = 150 PPM x (31.71 + 8)
---------------------
1,000,000
Lbs of nitrite = 0.0059565
That's pure nitrite. Now we'll figure the amount of
prague #1 this entails. As you've noted, prague #1 is
6.25% nitrite.
0.0059565 / 0.0625 = 0.0953040 lbs of prague #1
Converting to grams:
0.0953040 prague #1 x 16 oz x 28.35 grams = 43.2 grams
Finally, deduct the amount of salt in the prague powder
to get back to 3%.
43.2 grams prague #1 - (97.5 percent salt * 42.2 grams prague #1) =
40.5 grams salt to deduct = 0.09 lbs salt to deduct
Adjusted salt amount = 0.91 lbs - 0.09 lbs = 0.82 lbs salt
Final recipe:
1 8 lb brisket
3 gallons water
0.82 lbs salt
0.60 lbs sugar
43 grams prague #1 (rounded off)
Plus any other ingredients you use in your
pastrami recipe
As to your question about variablity due to differences
in the meat, experimenting with the above formula should be
enlightening (spreadsheets work well here).
You'll see that varying the meat water content % up or down a
few ticks has only a very small effect on the final numbers.
It's not really a significant factor.
> Any thoughts about this would be welcomed. I find very little on the
> internet about brine curing with nitrites and nitrates.
>
There are very few texts available *anywhere* that cover this
issue in adequate depth other than professional and academic
texts, which are very expensive and can be difficult to decipher.
I recommend "Cooking by Hand" by Paul Bertolli. It's an eye opener
in the area of cured meats, and it's packed with lots of other
great info, too.
<http://www.amazon.com/gp/product/0609608932/qid=1149013017/sr=2-1/ref=pd_bbs_b_2_1/102-0409680-2890544?s=books&v=glance&n=283155>
He also improves on some of the aspects of curing that Kutas
covers. That's no insult to Kutas, it's just that he's been gone
a long time and the field has been continually improving, as all
fields do.
> Again, sorry for the confusion
I didn't see any confusion on your part, just some good
analysis.
--
Reg