Which salt should you use for salting meat? This seems like a strange question, but as you will see, when it comes to curing meat and fish, not all salts were made equal.
In my post "Fulacht fiadh - salt extraction facility" I mentioned an article "Extracting Salt from Distichlis spicata (seashore saltgrass): Continued Investigations into Methods of. Salt Extraction and Salt Utilization in Prehistoric California". In it you can read that:
Many California tribes extracted salt from plants.
Various plants such as Distichlis spicata (seashore saltgrass), Petasites frigidus (sweet coltsfoot), Umbelliferae (Celery) were burned to create salty ashes which were then used as salt.
In some regions salt grass was burned on a grating of hardwood sticks which was laid over a pit full of hot coals. The salty sap oozed out of the plants and dropped on the coals, forming lumps which were extracted from ashes after the pit was cooled.
Another way of extracting salt from salt grass was by drying it on flat rocks and pounding it in mortar holes. The crushed bits were then winnowed using a circular tray which separated the salt from the grass. The resulting salt was then dampened and pressed into balls. The balls were broken as needed for use.
In some cases, the salty plants were were eaten raw.
Sometimes non saline grass was soaked in brackish water and then burned.
But this article contains another passage that is very very interesting indeed:
"Native groups in California extracted salt from salt springs, saline soil, rock salt, and saline and nonsaline plants. Salt was so valued by Native Californians that it was the number one trade item. All native American tribes from California either supplied or received salt from other groups, and 11 of the groups both supplied and received salt from different sources. For example, the Western Mono supplied rock salt and the TuleKaweah Yokuts supplied salt from salt grass to the Eastern Mono... "
This is very strange. Why would people exchange rock salt for grass salt and the the other way round? Salt is salt right? Wrong. Native Americans extracted "salt" from various green leaf plants. One of them belongs to the Umbelliferae family, commonly known as the celery, family. Plants belonging to celery family are super rich in sodium nitrates. And sodium nitrates in the meat get converted in sodium nitrites which kill one of the nastiest bacteria that can spoil the meat "C. botulinum" which causes botulism, potentially fatal illness.
The dehydrating and oxygen-depriving effect of salt (sodium chloride) in the wet or dry cure is effective against most of bacteria including Salmonella and E. coli. But salt can't kill C. botulinum. As a matter of fact, C. botulinum (or botulism) thrives in the absence of oxygen, so as the moisture (and dissolved oxygen) are drawn out of the meat by the salt, the dehydrated meat becomes an attractive environment to anaerobic bacteria like botulism.
Nitrates are converted in the food to nitrites. The nitrites are what controls the growth of botulism, by inhibiting certain metabolic processes of the bacteria.
All fruits and vegetables contain nitrates, and some contain significant amounts:
celery (all parts including the juice and the seeds)
beets (especially the beetroot)
leafy greens like spinach, chard and beet leaves
Ash produced from these plants will contain high level of nitrates. If plants were first soaked in salty water and then burned, the resulting salty ashes will contain both sodium chloride (salt) and sodium nitrate. This type of "salt grass" salt would have much better preservative effects if used as part of the smoking process than pure sea or rock salt, which is almost pure sodium chloride.
However even just using the above nitrate rich plants in a wet brine will protect from botulism on top of providing flavor to the meat. This is the equivalent of using Prague Powder #1 curing salt, the most commonly used curing salt which contains 6.25% sodium nitrite and 93.75% table salt.
Indeed, the addition of celery to the cure is what allows some ‘healthy’ commercially-cured meets to declare they are nitrate/nitrite-free, since what they add is celery. It’s not their problem that the celery provides nitrates.
Interesting don't you think? Is this why Native Americans extracted salt from "salt grasses" even though they were also able to extract it from brine and sea water and rock salt? And why they traded rock and sea salt for salt extracted from plants? Did they, although probably not knowing why, realize that salt extracted from plants was much better meat and fish preservative than rock, brine or sea salt?
I believe so.
But what about the ancient Irish? Is it possible that they also, unwittingly, used nitrate rich salt extracted from "salt grass" to cure their meat and fish? I believe so.
Celery (Apium graveolens), which we have seen is super rich in nitrates, has been cultivated as a vegetable since antiquity. But originally it was a wild plant which originally grew in salty marshlands. The original Wild Celery (Apium graveolens) is a plant of mainly coastal ground growing in salt-marshes or brackish ditches, by sea walls or streams – but it is rarely found inland.
It is quite possible that the ancient Irish, like the native Americans extracted salt from this plant. They definitely knew that the plant tasted salty. They could have burned the plant, and then added the ashes to the brine made in fulacht fiadh either during the salt extraction or during the meat and fish brining process. They could have also boiled chopped fresh leaves and stalks in a pot, using either charcoal piled next to the pot or fire heated stones dropped into it. Boiling extracts nitrates from the plant into the water. Cooled down nitrate rich celery soup could then be added to the brine. Brine enriched in such way would be would have proven to be much better meat and fish preservative to ordinary brine, made with sea salt.