Artificial Saliva and Ethnobotany

Look, sometimes you need quite a large volume of artificial saliva for very normal reasons. We’ve all been there. In my case, it’s because I was researching pre-contact fermentation practices in the Americas, and wanted an alternative to manually chewing starchy base ingredients (corn in the case of chicha, or mesquite beans in the specific case I was researching – more on that later.) What if, I thought, instead of manually chewing the beans I could instead put them in something like a mochi machine with my artificial saliva, and pseudo-masticate them that way.

It turns out I was not the first person to want artificial saliva, of course. There’s even a standard mixture: the Fusayama-Meyer Standard. You can buy it for $200/200 mL from Fischer Scientific, or $233 from Sigma Aldrich, and it’s widely used for testing dental metal alloys, among other uses. That’s a bit expensive, though, for what is mostly just me fucking around with some ethnobotany. Fusayama-Meyer does give us a good hint as to what we should include in our artificial saliva, however, specifically:

In fact, there are quite a lot of recipes used in scientific literature for artificial saliva, based on what the intended purpose is¹, and even more articles on the enzymatic, protein, and electrolyte composition of saliva². These give us a good starting place for our recipe.

So putting this all together, we have the following recipe:

Ingredients:

• 1 L distilled water
• 682.0 mg Potassium chloride (\(KCl\))
• 630.8 mg Bicarbonate of soda (\(NaHCO_3\))
• 600.0 mg Urea (\(CH_4N_2O\))
• 460.0 mg Disodium Phosphate (\(NaH_2PO_4\cdot 2H_2O\))
• 435.0 mg Potassium dihydrogen phosphate (\(KH_2PO_4\)) (source 1, 2)
• 340.0 mg Calcium chloride (\(CaCl_2\cdot 2H_2O\))
• 336.5 mg Sodium Sulfate (\(Na_2SO_4\))
• 262.8 mg Table salt (\(NaCl\))
• 244.6 mg Potassium Thiocyanate (\(KSCN\))
• 200 mg α-amylase (source 1)
• 178.0 mg Ammonium Chloride (\(NH_4Cl\)) (source 1)
• 5.0 mg Sodium Sulfide Nonahydrate (\(Na_2S\cdot 9H_2O\)) (optional)

All solid ingredients should be dissolved in the water, and the mixture should be used at approximately 30ºC. For storage, the dry ingredients should be kept as a dry mixture and only reconstituted as needed.

While this formulation ends up costing a decent amount (about $200 from amazon), that $200 is enough to make 230 L of saliva, with Disodium Phosphate and Potassium dihydrogen phosphate (followed by Potassium chloride at 733 Liters’ worth) being the limiting reagents. This makes our formulation roughly 1,150 times more cost-efficient than the Sigma Aldrich supply discussed above.

Why saliva though?

Ethnobotany

The real answer is that it comes from my misremenbering an indigenous fermentation practice I had read about. Willis Harvey Bell and Edward Franklin Castetter, in “The utilization of mesquite and screwbean by the aborigines in the American Southwest,” describe an indigenous tradition involving chewing mesquite beans by the people of the Colorado River delta in Baja, likely meaning the Xawiƚƚ kwñchawaay (Cocopah) nation.

“At the end of the first quarter of the nineteenth century, Pattie (135 :94), Indian trader and trapper, noted that the Indians of New Mexico and Arizona pounded mesquite pods in a mortar and made the pulp into bread, while Hardy saw the plant about the same time in Baja California on both sides of the Colorado River, and observed that the Indians in the latter region allowed mesquite pods to ferment in water in an earthen bowl. They chewed these pods to remove the fermenting liquid, then spat them back into the bowl. He recorded that the Indians of Tiburon Island [the Comcáac (Seri) people] engaged in this same practice (61 :330-37, 434, 446).”³

I, or the wikipedia editor whose work I was reading, misremembered or misunderstood this to mean that the beans were chewed in a similar manner to the production of Chicha de muko or Kuchikamizake. This does not seem to have been the case, however,

After extensive searching, the only reference I could find to fermented mesquite comes from La Barre (1938)⁴:

“Algoroba, a South American beer made from the fruits of leguminous plants, Prosopis alba, P. pallida and P. juliflora (mesquite beans)

…

Kiwa, a Gran Chaco [the people of modern-day Bolivia] name for algoroba; Prosopis juliflora beans are chewed and fermented in goat-skins, as the natives chant and beat the drum to drive away evil spirits who would spoil the brew. Only men drink it.”

And while the “chewed and fermented in goat-skins” is tantalizing, it seems more likely that the chewing was done to mechanically break up the fibrous mesquite beans into a paste that could be more easily fermented. Indeed, other references to chewing of mesquite beans in Bell and Castetter seem to confirm that any chewing and spitting practice was primarily done to extract extant sugars, rather than digest starches into new ones³.

about the Yavapai:

“Pulverized beans were moistened in a water-tight basket, the juice expressed with the hands into another container and drunk, or the wet meal might be placed in the mouth, the juice sucked from it and the residue spat out (56:259; 55: 211).”

About the Aha Makhav (Mohave):

“The pods were crushed with this pestle, or, more rarely, a wooden one, the hard seeds remaining whole. Sometimes the meal was eaten raw, the seeds being shaken out in the hand, but more often it was mixed with water and the sweet liquid drunk. The remaining dough was carried to the mouth in hand- fuls, sucked out and replaced, to be soaked in water a second time before being discarded. Sometimes the fresh dough was made into a huge jar-shaped cake, covered with wet sand, and baked, and was so hard after baking that it had to be cracked with a stone. In eating the seeds were spat out or swallowed whole (85:736-37; 79 :24; 87:222).”

And about the Xawiƚƚ Kwñchawaay/Cocopah:

“Large quantities were gathered and reduced to meal in cottonwood mortars with a long mesquite wood pestle. The meal, after being soaked in water, was sucked for its saccharine content, after which the residue was spat out (29 :203; 9 :53; 82 :52; 54 :267, 270). Barrows records the fruit as the “staple of life” (9 :56).”

This makes sense: mesquite beans, unlike rice or corn, are not particularly starchy, instead being comprised of Sucrose (21%), crude fiber (20-30%), and protein (10-15%)⁵. They therefore would not have particularly benefited from the alpha amylase predigestion that saliva offers.

Conclusion

While mesquite may not have needed mastication-assisted saccharification to be drinkable or even fermentable, there are notable examples of fermentation traditions that did use this method (Chicha de muko and Kuchikamizake, for example.) Maybe I’ll make one of them sometime, and see how our saliva compares to more “modern” techniques like malting of the corn. Until then.