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Question #90206 posted on 09/07/2017 8:28 p.m.
Q:

Dear 100 Hour Board,

What edible liquids are there that don't have water as the base? The only one I can think of are the oils (vegetable oil, olive oil, etc). I thought maybe vinegar, but it is mostly water, with some acid in it. Ideas?

-Hansoil and Vinaigretel

A:

Dear Frank,

Yeah, you've got water-based liquids and edible oils. Sherpa Dave observes that alcohols are edible, and while this generally weak-sauce Quora thread debating your same question sometimes argues otherwise, I have most certainly seen people take small swigs of very nearly pure ethanol in a Bolivian silver mine (this does not make the preceding statement more factually correct, but perhaps it does make it more interesting). 

The aforementioned putrid enlightening Quora article does mention hot liquid sugars as an edible liquid (though their edibility may be limited by their temperature). Additionally, depending on what you've cooked up some super-saturated sugar syrups could become concentrated enough to conceivably consider them more sugar than water, be at an easily edible temperature and therefore maybe fit your definition.

While we're sweet-talking, I'll also persuade you to consider honey, which is just 17.1 percent water and composed primarily of fructose and glucose.

There is a list of food pastes on Wikipediayou know, food paste as in the "semi-liquid colloidal suspension, emulsion, or aggregation used in food preparation or eaten directly as a spread" everyone knows and loves, and which you could argue to be a sort of edible liquid—depending on the limit at which you consider something to stop being water or oil-based and—in the words of R'as al Ghul of Batman Begins—"become something else entirely." 

I don't think you're really looking to find out about bean and fish pastes, but what of the amino and fatty acids these contain? Are some of these liquid at room temperature and comestible in an isolated, pure form? While I suspected figuring these out involved a level of organic chemistry outside the scope of this question, I got a little too excited after work one day and researched:

  1. Essential amino acids—not to be confused with "liquid aminos," a food product/condiment containing amino acids similar to soy sauce—I looked up the melting points of the 21 compounds used by humans for protein synthesis by their L-compound pages on the very exciting (#nerdz4lyfe) PubChem Open Chemistry Database, where I discovered glutamine and apparently reactive selenocysteine had the lowest melting points at 185 °C and 143 °C, respectively.  In other words, these are solid. Get out of the way, amino acids. 
  2. The omega-3 fatty acids humans use, which since you obviously want to know are α-linolenic, docosahexaenoic, and eicosapentaenoic acids—still with me, Frank? Your eyes looked as glazed as a dozen Krispy Kremes there for a second—so based on the PubChem thing and some mysterious Google direct results I found out those funky-sounding acids—uh, your eyes are doing the thing again—are definitely liquid at room temperature, and insofar as I can tell are edible. Of course, I suspect all edible oils are composed of fatty acids, so despite my Google-fu I've only managed to re-assert what you said about edible oils being... edible. **sigh...**

There's glycerol, which is sweet, clear, viscous, and often used as a sweetener and filler in different foods, as well as cosmetics and industry. Though it is commonly synthesized from animal tallow, palm and soybean oil, it lacks fatty acid chains and so I consider it to be a separate edible liquid.

Anathema pointed out liquid nitrogen as a possibility but noted a Google search showed there was controversy about safety risks, and indeed I found prominent mentions of a case where a British 18-year old was hospitalized and received an emergency gastrectomy after she consumed a cocktail containing liquid nitrogen. From an interesting BBC article written about the accident I found the following passage:

Science writer and fellow at the Royal Society of Chemistry John Emsley says if more than a "trivial" amount of liquid nitrogen is swallowed, the result can be horrendous.

"If you drank more than a few drops of liquid nitrogen, certainly a teaspoon, it would freeze, and become solid and brittle like glass. Imagine if that happened in the alimentary canal or the stomach.

"The liquid also quickly picks up heat, boils and becomes a gas, which could cause damage such as perforations or cause a stomach to burst," he says.

However, Emsley says he would be surprised if anyone could actually swallow that much liquid nitrogen.

"It would be extremely cold in anyone's mouth - people would want to spit it out immediately," he says.

But Dr Alex Valavanis, a research fellow at the Institute of Microwaves and Photonics, at the University of Leeds, believes it would be perfectly possible for someone to swallow a mouthful before they became aware of any ill effects, as liquid nitrogen "does not immediately feel cold".

He says the delay in feeling the cold is down to the "Leidenfrost effect" - which happens when a liquid, in near contact with a mass significantly hotter than the liquid's boiling point, produces an insulating vapour layer.

But he agrees a mouthful of liquid nitrogen - which would turn into about 25 litres of gas - could do "catastrophic damage".

(One entertaining news quote from a similar article: "Lancashire Police have not officially named the place where she bought the cocktail, but say Oscar's [wine bar] has stopped selling it." Well, I guess I won't officially name Oscar's either.)

For prudency's sake, we shall discount liquid nitrogen from the running. Too cool for school, eh, Nitrogen? **cackles coldly**

Frank, are we therefore forever doomed to be imbibing water, alcohol and oil-based substances? Not to fear, science is here! Let's now have fun with propylene glycol, used chiefly for manufacturing and industry, but also in food. According to a well-documented Wikipedia article,

The acute oral toxicity of propylene glycol is very low, and large quantities are required to cause perceptible health damage in humans; propylene glycol is metabolized in the human body into pyruvic acid (a normal part of the glucose-metabolism process, readily converted to energy), acetic acid (handled by ethanol-metabolism), lactic acid (a normal acid generally abundant during digestion), and propionaldehyde (a potentially hazardous substance).

Serious toxicity generally occurs at plasma concentrations over 4 g/L, which requires extremely high intake over a relatively short period of time, or when used as a vehicle for drugs or vitamins given intravenously or orally. It would be nearly impossible to reach toxic levels by consuming foods or supplements, which contain at most 1 g/kg of PG, except for alcoholic beverages which are allowed 5 percent = 50g/kg. Cases of propylene glycol poisoning are usually related to either inappropriate intravenous administration or accidental ingestion of large quantities by children.

In other words, it's a relatively safe chemical that isn't harmful in small doses, unless you do something stupid, which if "accidental ingestion of large quantities by children" indicates anything to me, it is that the small among us are the best, most adventurous, and most likely to attempt to down a couple bottles of imitation vanilla extract, where I often see propylene glycol listed as an ingredient and flavor solvent. I think these flavorings generally contain water as is the case with this Kroger brand, but I don't know what in what proportions.

Now, the oral LD50 (Wikipedia: abbreviation for "Lethal Dose, 50%" or median lethal dose. It is the amount of the substance required (usually per body weight) to kill 50% of the test population.)" of propylene glycol is 20 grams per kilogram in rats and 2.2 g/kg in mice. So how much of our favorite chemical would it take to kill a human?

As people are not mice or rats (whaaaaaat?!?), it is difficult to say. We've previously learned serious toxicity occurs at 4 g/L of plasma. Your average human has, say, 2.7 to 3 L of blood plasma. If injected directly and intravenously, serious toxicity would occur somewhere around 12 g or 11.6 mL. But we wouldn't be doing that, because we want to know how much we could drink, and the body metabolizes the stuff. As Dr. Sean O'Keefe, a food professor contributing to BestFoodFacts.org  explains:

Propylene glycol adds sweetness, body, and can be used as a solvent for flavorings...

It is perfectly safe to consume foods containing propylene glycol (PG). Propylene glycol can only be toxic if used intravenously at high dosage or when applied to compromised skin (burns). Once ingested, PG is either excreted in the urine or is metabolized to lactic acid, a normal metabolic product. Ethylene glycol (used in car antifreeze) is toxic because it is metabolized to oxalic acid, which is toxic. 

Right. So there's metabolism into lactic acid, or excretion via urine of the extra, unmetabolized propylene glycol, but also know there's limits to this ability courtesy of our research a source or two ago—remember "serious toxicity occurs" and "extremely high intake over a relatively short period of time?"—so the ardently burning question we all never knew we had remains: how much propylene glycol could a human adult imbibe before succumbing? 

Again, we only have data for mice and rats, but this is the Board... and for you, Frank, we'll take a step off the plank of certainty straight into the deep end of conjecture. 

Let us take a group of 20 consenting average adults, who for ease of reference will all be named, say, Peter Pettigrew. Let us assume our Peters are of average British weight (nationality randomly assigned) at 75 kg/167 lbs (for comparison average North American adults are 81 kg/178 lbs and average global adult weight is 62 kg/137 lbs). Let us also assume the oral LD50 for the Peters Pettigrew is equivalent to that of rats, again, 20 g/kg. Science will now occur. The assembled Peters Pettigrew begin to chant in unison in unexpected anticipation of the trial.

Assignments into control groups, unknowingly given—you will corroborate the data!
Consent of the subjects, willingly given—you will avert legal disaster!
Selfies with fellow participants—forcibly taken—we shall regard as foe!

It's probably good they had this team-building moment, because upon subsequently consuming 1.45 L of the sweet, clear substance in a chugging contest several Peters Pettigrew have disappeared, an unexplainable handful of delirious rats are scurrying madly around the room, three Peters appear to be having serious regrets and ten of the poor blokes are straight-up dead.  It appears no one bothered to assign a control group. 

"This is your fault, Frank," one livid rat scratches into a wall. 

Indeed, he's right. I hope you're happy, Frank.  Just go ahead and try to pass the buck off to "science," like you always do—we see the strings that control the system. We'll be watching you. 

TL;DR: Edible liquids besides water include oils, sugars, alcohols, and a variety of chemicals (including glycerol and propylene glycol), where dosage determines edibility or toxicity.

Suerte,

--Ardilla Feroz and the Remaining Peters Pettigrew, with moral support from The Amazing Maurice and his Educated Rodents

P.S. Should you wish to search out more edible liquids, I present to you the FDA's Food Additive Status List and the accompanying GRAS Subtances (SCOGS) Database, GRAS and SCOGS, meaning Generally Recognized as Safe and Select Committee on Generally Recognized as Safe Substances, respectively. Let me know if you find anything cool, like I did when I found out urea was edible. Something like that, Frank. This explains a lot about Grandpa's offering at the family potluck in Saskatchewan. I'd thought for sure we'd prevented him from finding the ingredients for his infamous mystery casserole in those frigid prairies, but I was wrong, Frank. I was wrong.

P.P.S. For all our desktop board readers out there, all them hyperlinks be hovertext enabled. Awww yisss. Also, if you liked this answer, do email me at ardilla.feroz@theboard.byu.edu if you are so inclined because this took like 14 hours to write (haven't spent time like that since the women, pigeons and Islam question or maybe the the Declaration of Tinderpendence); I could use some validation and preferably sugary edible liquids right now.

P.P.P.S. Not deodorant, though, for while I suspect melted deodorant might taste sweet—propylene glycol is often a main ingredient in non-antiperspirant varieties—I just purchased like a year's supply of the fancy Old Spice kinds and even if it were a food and I didn't have concerns about the non-PG ingredients I'd be okay for a while.