Ever heard of the pyruvate scale? No, we thought not.
by John Pope on July 24, 2015
There are scales to measure all sorts of things, from the level of technological development of a society to the progression of male pattern baldness.
When it comes to food, some are well known like the Scoville scale (heat of chillis) and some are less so, like the Pyruvate scale.
I wasn’t even aware of the existence of this scale until this morning when I was killing time on a train and playing a silly quiz game on my phone which asked me a question about it. Intrigued I went on a little bit of a research mission, but failed abysmally to find very much information at all.
The wikipedia entry states the following, and pretty much every other web reference that I have found so far gives a slightly edited copy/paste version of the same text:
The pyruvate scale measures pungency in onions and garlic with units of µmol/gfw (micromoles per gram fresh weight). It is named after pyruvic acid, the alpha-keto acid co-product created in the biochemical pathway that forms syn-Propanethial-S-oxide, the main lachrymatory agent in onions.
The standard onion has an eight rating, while “sweet onions” have a two or three rating on the scale. The lower the score or scale the more “sweet” the onions are rated. Anything less than five is considered a sweet onion.
The Vidalia onion variety is considered sweet and must have a score of 5.0 µmol/gfw or less. The Supasweet onion (usually grown in Lincolnshire, England) registers 1.5 to 2 on the scale. A standard brown onion is usually in the range of 6-7 out of 10.
Soil type, rain, and sunlight affect the pungency in onions and garlic and, therefore, their score on the pyruvate scale.
I have absolutely no practical application at all for this scale, but that doesn’t mean that I don’t want to know more, I do, I so do. Any onion experts please please get in touch or enlighten us all in the comments below.
Oh, and just as an aside, there are a couple of interesting things to note about pyruvic acid:
- The derivative bromopyruvic acid is being studied as a potential cancer treatment
- It kills microbes and repel insects (hence eating raw garlic as a mosquito repellent)
- It damages the red blood cells of cats and dogs (why you shouldn’t fee onions or garlic to your pets)