Sugar, Ulcer Treatments, Coal Tar, and All That Tastes Sweet

But as clever and greedy as we are, humans of course want to be able to enjoy our sweet, sugary flavours without the associated downsides. Thus, we have a wonderful rainbow of non-sucrose sweeteners that are either low calorie or “zero calorie”. In reality, many “zero calorie” sweeteners do, in fact, have some caloric value— even if only from fillers. However, labeling conventions from The US Food and Drug Administration (FDA) typically allow for any product with calories below five per serving to label and advertise as being “zero calorie”.

Perhaps the most infamous of the non-sucrose sweeteners is aspartame, discovered accidentally in 1965 by the chemist James M. Schlatter, who was studying ulcer treatments for Pfizer company G.D. Searle. Aspartame was synthesized as an intermediate to one of the peptides he was working with, but due to undoubtedly horrendous laboratory practice, had some contaminated on his fingertips. When he licked his fingers to pick up some paper he discovered they tasted incredibly sweet. However, if any of you do this in your labs I will personally parade you through the PAC during exam time in nothing but your nitrile gloves chanting “shame”.

Most distinguishable by its pronounced aftertaste, aspartame is found in most “diet” sodas. It is actually a derivative of a dipeptide of aspartic acid and phenylalanine. As a result, higher temperatures hydrolyze this dipeptide bond, making it unusable as a sugar alternative in baking. It also hydrolyzes readily into these two amino acids during digestion, which is metabolized in the body like any other nutritional source of these amino acids. This results in it not being zero-calorie—however, it is approximately 200 times sweeter than sucrose, meaning that its typical 4-calorie-per-gram energetic “cost” is highly negligible, as a noticeably smaller amount of aspartame is needed to achieve the same “sweetness” as sucrose. In addition, the nice blue package of aspartame does not affect blood sugar levels, a great benefit for diabetic individuals.

The next compound was discovered by… similarly poor means. In 1976, researcher Shashikant Phadnis was working with synthetic derivatives of sucrose, particularly one chlorinated variety, when he was asked by co-worker Leslie Hough to “test” it, which he misheard as “taste”. Yeah. Please promise me, if your boss or TA ever asks you to taste ANYTHING in the lab, at least ask them to confirm that yes, they want it to go onto your tongue. What Phadnis tasted was incredibly sweet, and was the yellow-packaged compound we know now as “sucralose”.

Sucralose, unlike aspartame, retains its sweetness after being heated, making it applicable as a sugar substitute in baking applications. It also boasts more than double the marketable shelf life, making sucralose (found most notably under the brand name of Splenda) a far more prominent non-caloric alternative to sugar. It is synthesized via the chlorination of sucrose, resulting in the substitution of three hydroxyl groups with chlorine. While this functionalization allowed Splenda to use the tagline “Made from sugar, so it tastes like sugar” in advertisements, it also is the reason why the sweetener is “zero calorie”. The chloride functional groups typically prevent the compound from even being absorbed into the gastrointestinal tract, with 75-90% of sucrose ingested being directly excreted as faecal mater. Of the sucralose absorbed, approximately 70-80% is removed from the blood stream by the kidneys and excreted as urine. This results in only 2-8% of ingested sucralose being metabolized. Sucralose is reported as being anywhere near 300–1000 times sweeter than sucrose.

Next, we have saccharine, often found as Sweet’n’Low in the pink packets (outside of Canada, that is), which is the oldest of the non-sucrose sweeteners. It was discovered… sigh… by accident… again. Constantin Fahlberg, a chemist working at John Hopkins University in Maryland, was working with derivatives with coal tars in 1879. Yep. Coal tar. In the evening after work, he discovered that his hand tasted surprisingly sweet, and linked it to a benzoic sulfimide compound. This would further be developed into the benzothiazol-based compound that we know and use today.

While it it 300–400 times sweeter than sucrose, saccharine also has a characteristic aftertaste, often described as metallic. As a result, it is often mixed with other sweeteners in order to make this aftertaste less noticeable. It is also heat-stable, making it usable in baking. It also is considered “0 Calorie” due to it not being absorbed or metabolized during the digestive process.

Interestingly enough, if you take a look at the “list of ingredients” on a Sweet’n’Low packet you’ll find in Canadian restaurants, saccharine will be nowhere to be found; instead, you’ll find sodium cyclamate, which was also found through horrendous lab practices. I swear, this article isn’t meant to condone bad laboratory hygiene. The story goes that at the University of Illinois in 1937, grad student Michael Sveda was working on medication for fever, when he set his cigarette down on a lab bench (this should go without saying that smoking in a laboratory is MUCHO bad idea), he found it to taste surprisingly sweet. Other versions of this story simply suggest that Sveda had tasted his fingers, not a cigarette.

Sodium cyclamate, unlike the other sweeteners discussed, is only 30–50 times sweeter than sucralose, but still has a distinct aftertaste. While being heat-stable, it is also notably less expensive than any of the other sweeteners.

However, both saccharine and sodium cyclamate’s history in approval for consumption is murky. Both substances were independently found to be a potential carcinogen during animal studies. In the US, this resulted in the banning of cyclamate in 1969, but interestingly enough, not saccharin. Instead, all substances containing saccharin simply had to possess a warning label stating “Use of this product may be hazardous to your health. This product contains saccharin which has been determined to cause cancer in laboratory animals”. This requirement was lifted in 2000, after research suggested that the rat behaviour was not comparable to human toxic effects at typical levels of consumption.

Canada, on the other hand, banned saccharin for a time, opting to use sodium cyclamate in its place. This Canadian ban on saccharin was lifted, while cyclamate salts are still banned in the US, despite research suggesting the previous results non-applicable to humans. This is why the chemical contents of Sweet’n’Low brand sweetener will vary across the border.

Finally, Stevia is the most uncommon of the non-sucrose sweeteners in North America. When it is found, is in a green packet. However, it isn’t new to the rest of the world— the plant Stevia rebaudiana, from which it is extracted, has been used for 1.5 millennium by the indigenous peoples of South America for use in teas and general sweet treats. It was named for the Spanish botanist Petrus Jacobus Stevus. It wasn’t until 1931 when the chemical compounds that gave the plant its sweet taste—particularly its glycosides, now known as Steviol—were identified. They are isolated via crystallization techniques after drying the plant and extracting the glycosides via water extraction.

Stevia is approximately 150 times sweeter than sugar and is stable at higher temperatures. It is often reported as having a bitter, almost liquorice-like aftertaste. Stevia was first available in Canada as a food additive in 2012, while it remains unauthorized by the FDA for use in the United States, the FDA’s website stating: “FDA has not permitted the use of whole-leaf stevia or crude stevia extracts because these substances have not been approved for use as a food additive.”. Interestingly, though, Truvia and PureVia, which both use glycosides extracted from the Stevia plant, has been approved by the FDA due to being a “highly purified product”, not the crude substance previously described.