The Sal Ammoniac Project
by: Eben van Tonder
4 February 2018
An installment in the series, The Salt Bridge
Studying curing salts from antiquity, I realised that sal ammoniac (ammonium chloride) was probably the first curing agent with universal appeal and traded across Europe, China, India, and Africa.
This remarkable mineral was naturally harvested from caves in mountains from Tibet and the Smoky Mountains of Turfan to the mountains surrounding Samarkand. From the Siva Oasis in ancient Lybia where the famed temple of Amun stands to, I am sure, the Danakil Desert in Ethiopia which has the same climate and volcanic vents found at the Smokey Mountains in Turfan. From these locations, it was traded into Saltsburg, the heart of Europe, the Mediterranean, and eastern China and India.
On paper the ammonium chloride (NH4Cl) should cure meat as fast and effectively as saltpeter, but what can we learn from interacting with the salt in real life?
I embarked on this fascinating journey after Christmas 2017 with two very small experiments to start learning more about the practical application of this ancient curing salt.
As background to this article, read:
Does it drop the temperature of meat sufficiently to assist in curing?
The first experiment was to see if it would drop the temperature sufficiently to assist in curing as I have speculated in earlier articles. Without running the equations, I wanted to see how much it actually reduces the temperature of water for a given quantity of the salt. Why think if you can test? So, one day after work, I bought a small mg scale from a Chinese retailer in Kraaifonteion, picked up a bag of ammonium chloride and had some fun at home. I recruited an assistant (my daughter, Lauren), took some shot glasses out of the cupboard and the science experiment was underway.
To test it, I wanted to see what happened in water first.
The water temperature started at 22.6 deg C.
We added 1% ammonium chloride and it dropped to 22.3 deg C.
4% – 20.4 deg C.
6% – 19,2 deg C.
8% – 18.1 deg C.
10% – 17.5 deg C.
20% – 11 deg C.
30% – 6.9 deg C.
I tested it on meat and rubbed as much of it on the meat to cover the meat with a thick crust, but this had a negligible impact on the meat temperature. I was, therefore, wrong to suspect that applying sal ammoniac would reduce the meat temperature. Of course, it could have been used as a coolant to place a container with meat being cured into, in order to reduce the temperature of the meat.
Next was the even more fundamental question of its efficacy to cure meat. Will it preserve the meat and does the characteristic cooked/ cured pinkish/ reddish colour develop? What does it taste like? (matters of its toxicity will be considered later).
Does it cure meat?
On 27 Dec 2017, I selected a belly which I cut into three pieces. One I treated with sal ammoniac (2%) and sodium chloride (4%), sample 1. The second, I treated with sal ammoniac (0.125%) and salt (1.55%), sample 2. Sample 3, I treated with Prague powder (0.25%) and salt (1.5%).
Sample 1, the 2% sal ammoniac, 4% NaCl, I placed in a plastic bag with no vacuum. Sample 2, the 1.5% NaCl and 0.125% ammonium chloride, I vacuumed sealed. The 1.5% NaCl and 0.25% Prague powder, I sealed in a vacuum bag. The meat temperature was at 7 deg C.
The sodium chloride and sal ammoniac were weighed, mixed together and hand-rubbed onto the meat. It was stored in a chiller where a 7 deg C temperature was maintained throughout the month of testing and observations.
By 10 Jan, 14 days after curing, the ammonium chloride treated meat, in my estimation, had the brightest cured colour.
Here is sample 1, the ammonium chloride that was not vacuum packed.
Sample 2, the vacuum packed ammonium chloride.
By 15 Jan 2018, 19 days after the test began, the meat cured with ammonium chloride changed colour. This change of colour was first observed two days earlier on the 13th of Jan, but by the 15th, it was clearly noticeable.
Compare the bright colour of the nitrite cured sample and the vacuum packed ammonium chloride sample.
And the colour of the non-vacuumed ammonium chloride cured sample.
On 26 Jan 2018, I opened the vacuum packed samples.
Sample 1. The meat exposed to the air turned into wooden brown, due to oxidation, no doubt. Despite the colour on the outside browning, the meat in the center was still pink and the meat had a pleasant fresh meat smell. The fresh meat smell was so distinct that I called in a colleague to confirm the smell in case I was being tricked by my senses by making me smell what I would like to smell. This shows that in this instance, 2% sal ammoniac and 4% sodium chloride, not under vacuum, stored at 5 deg C was sufficient to preserve the meat very well for a month.
Sample 2. The vacuumed sealed meat cured with ammonium chloride maintained its dark purple colour, but darkened, probably due to a loss of vacuum over the month. Most interestingly, this sample was off, with a distinct foul smell. In this instance, 0.125% sal ammoniac and 1.5% sodium chloride was ineffective in preserving meat at 5 deg C, and vacuum packed over a month.
Sample 3. The vacuum sealed meat treated with sodium nitrite retained its bright pinkish/ reddish colour. The sample of nitrite cured meat had a similar foul smell as the ammonium chloride treated meat, even though less – about half in intensity. In this instance, the 0.25 Prague Powder and 1.5% sodium nitrate was not sufficient to preserve meat under vacuum, at a 7 deg C temperature.
I put the samples in water for three hours to draw out excess salt.
On 28 Jan 2018, I sliced the sal ammoniac sample which worked. Exactly a month after I started the curing process.
The meat was smoked and heat treated to a core temperature of 55 deg C for three hours with beach wood. It was then sliced and vacuum packed. The vacuum packed 4% sodium chloride and 2% sal ammoniac cured meat presented a beautiful cured colour after a month of curing. We fried it up and tasted it. The meat had a slightly, but very distinct tangy taste which was strange, but not unpleasant at all.
Sal ammoniac, in our estimation, would definitely be acceptable as a meat curing agent at a concentration level of 2% with a little bit of salt, even in the absence of a vacuum. The taste is not bad (definitely edible) and the preserving power impressive.
Ignoring the matter of toxicity, applying sal ammoniac at a 2% ratio to the meat would not have directly impacted the meat temperature contrary to what I expected. What the ancients, of course, could have done, was to add 30% sal ammoniac to water, reduce the water temperature to almost 5 deg C and place the container with the the meat being cured into this as a cooling device to assist in the preservation of the meat for the two weeks it took to cure properly, if daytime temperatures rose high and a cool area could not be found to store the meat.
It will be interesting to test it against potassium nitrate and sodium nitrite at the same concentration levels.
(c) Eben van Tonder