- Oct 9, 2018
- 382
- 538
Hi,
I have a question about calculating nitrite levels in meat. I know this isn’t a new topic, but I’ve not seen a detailed discussion of the calculations or the physical assumptions that go into the calculations.
According to the USDA’s Processing Inspectors' Calculations Handbook, nitrite levels are calculated using the following equation for meats cured by immersion or pumping:
ppm = (weight nitrite * % pick-up / weight water)*1000000.
If pumping, %pick-up=%pump.
(https://www.fsis.usda.gov/wps/wcm/c...4da3-905b-fa240974a5a9/7620-3.pdf?MOD=AJPERES)
Comparing two popular sources; vastly different assumptions seem to be made regarding the value (and meaning) of % pick-up. Details are below. In my example calculations, I assume a 20 pound ham, and 1 gal of water, and I am seeking to obtain 150ppm nitrite in the meat.
Source 1 says 91g Cure #1.
Source 2 says 31g Cure #1.
Can anyone provide some insight, an academic reference, or an industrial reference?
----------------
Source 1: S. Marianski. Author of several books, and a web site. I can’t find any information about his formal training/education/career.
Ham: 20 lb (9072g)
Water: 1 gal = 8.36 lb (3792 g)
Cure # 1: 0.2lb (91g)
Nitrite: 0.2*0.0625 = 0.01 lb (6g)
ppm nitrite in water = (6g / 3792 g)*1000000 = 1500ppm
If the ham is pumped with 2 lb (907g) of cure (i.e., 10%):
ppm nitrite in meat = 1500*0.10 = 150ppm
If not pumping, Marianski says 4%pick-up is a reasonable assumption:
ppm nitrite in meat = 1500*0.04 = 60ppm
So, according to Marianski, the amount of nitrite in the meat, is proportional to the amount of curing solution it absorbed (or was pumped with). This seems consistent with the USDA’s Calculations Handbook: “…assumes that the meat or poultry absorbs not more than the level of nitrite in the cover pickle.” (Page 22)
---------------------
Source 2: G Blonder PhD. Professor of mechanical engineering at BU. PhD in physics. Lots of peer-reviewed publications, and is highly cited (h-index 48) – but not in the field of food science. So, although he’s a very accomplished academic, he’s not technically a food scientist.
The amount of cure #1, was obtained from a nitrite calculator he developed and has posted on his web site. His calculator assumes no pumping. To get 150ppm nitrite, Blonder’s calculator says you need:
Ham: 20 lb (9072g)
Water: 1 gal = 8.36 lb (3792 g)
Cure # 1: 0.07lb (30.9g)
Nitrite: 0.07*0.0625 = 0.004 lb (1.9g)
Therefore;
ppm nitrite in water = (1.9g / 3792 g) * 1000000 = 509ppm
To get 150ppm, the calculator must be assuming a 30% pickup?
There is no way that the meat absorbs 30% of its weight in water. Blonder must therefore be saying that the meat is filtering the nitrite out of the water. This seems contrary to the USDA guidelines. Unfortunately, I can find no explanation or justification for this calculation.
----------------
Thanks for reading,
I have a question about calculating nitrite levels in meat. I know this isn’t a new topic, but I’ve not seen a detailed discussion of the calculations or the physical assumptions that go into the calculations.
According to the USDA’s Processing Inspectors' Calculations Handbook, nitrite levels are calculated using the following equation for meats cured by immersion or pumping:
ppm = (weight nitrite * % pick-up / weight water)*1000000.
If pumping, %pick-up=%pump.
(https://www.fsis.usda.gov/wps/wcm/c...4da3-905b-fa240974a5a9/7620-3.pdf?MOD=AJPERES)
Comparing two popular sources; vastly different assumptions seem to be made regarding the value (and meaning) of % pick-up. Details are below. In my example calculations, I assume a 20 pound ham, and 1 gal of water, and I am seeking to obtain 150ppm nitrite in the meat.
Source 1 says 91g Cure #1.
Source 2 says 31g Cure #1.
Can anyone provide some insight, an academic reference, or an industrial reference?
----------------
Source 1: S. Marianski. Author of several books, and a web site. I can’t find any information about his formal training/education/career.
Ham: 20 lb (9072g)
Water: 1 gal = 8.36 lb (3792 g)
Cure # 1: 0.2lb (91g)
Nitrite: 0.2*0.0625 = 0.01 lb (6g)
ppm nitrite in water = (6g / 3792 g)*1000000 = 1500ppm
If the ham is pumped with 2 lb (907g) of cure (i.e., 10%):
ppm nitrite in meat = 1500*0.10 = 150ppm
If not pumping, Marianski says 4%pick-up is a reasonable assumption:
ppm nitrite in meat = 1500*0.04 = 60ppm
So, according to Marianski, the amount of nitrite in the meat, is proportional to the amount of curing solution it absorbed (or was pumped with). This seems consistent with the USDA’s Calculations Handbook: “…assumes that the meat or poultry absorbs not more than the level of nitrite in the cover pickle.” (Page 22)
---------------------
Source 2: G Blonder PhD. Professor of mechanical engineering at BU. PhD in physics. Lots of peer-reviewed publications, and is highly cited (h-index 48) – but not in the field of food science. So, although he’s a very accomplished academic, he’s not technically a food scientist.
The amount of cure #1, was obtained from a nitrite calculator he developed and has posted on his web site. His calculator assumes no pumping. To get 150ppm nitrite, Blonder’s calculator says you need:
Ham: 20 lb (9072g)
Water: 1 gal = 8.36 lb (3792 g)
Cure # 1: 0.07lb (30.9g)
Nitrite: 0.07*0.0625 = 0.004 lb (1.9g)
Therefore;
ppm nitrite in water = (1.9g / 3792 g) * 1000000 = 509ppm
To get 150ppm, the calculator must be assuming a 30% pickup?
There is no way that the meat absorbs 30% of its weight in water. Blonder must therefore be saying that the meat is filtering the nitrite out of the water. This seems contrary to the USDA guidelines. Unfortunately, I can find no explanation or justification for this calculation.
----------------
Thanks for reading,