by dougal » Fri Aug 25, 2006 3:21 pm
OK. I'll have a go.
Lets work in consistant units g and kg. Not gallons and pounds!
Mixing the cure: They say 2 lbs to a gallon of water. That'll be a US Gallon so about 8.33 lb.
So having established the ratio 2:8.33 we could convert to any other weight units.
Your ham weighs 5.67 kg so 10% of that would be 0.567 kg or 567g of brine to be injected.
Following Oddley's suggestion of having some for the thing to sit in for a week or so, lets mix up some extra. How much extra? How about something like a litre and a bit for its bath?
Taking our 2:8.33 ratio, we might mix 400g of cure mix with 1666g of water to make 2066g of brine.
Injecting about 570g (note that is NOT 570cc) of this brine should leave plenty enough for a bath.
Just injecting it, we will have 567g of brine, containing 2�(2+8.33) of the 567g injected being dry cure ingredients, ie 109.8g of dry cure, implying 0.82g of nitrite (0.75%).
Relating the 0.82g of Nitrite to the starting 5670g of meat is about 0.000145 of the meat weight or 145ppm, nicely below the US limit of 200ppm.
But we want to soak it as well.
Since the dry cure contains 0.75% of Nitrite, there's a total of 400 x 0.75 � 100 = 3g of Nitrite *total* in there whether pumped or in the residual brine.
If we immerse it long enough to reach equilibrium, 5.67 � (5.67 + 2.066) of that, ie 0.733 of the 3g, ie 2.20g would be in the meat (according to the Meat Inspectors Handbook concept).
2.2g compared to the 5670g meat is 0.000388 or 388ppm
The US limit is 200 ppm, so we don't want to let it get to equilibrium by immersion.
So 145ppm from the pumping, but soak it in the remaining brine for long enough and it could end up as high as 388ppm.
I don't know how to calculate how quickly the nitrite concentration would rise towards equilibrium.
If we **assume** that it would rise linearly, and that it would attain equilibrium in 4 weeks, then it would pick up about (388-145)�4 ie 61ppm per week.
Hence at the end of the first week it would be about 145 + 61 = 206ppm or just fractionally beyond the US limit.
Hence (if the assumptions are valid and my numbers are right) there shouldn't be any harm giving it seven days (but no longer) immersion in the residual brine.
How do those numbers look to others?