The pyruvate scale measures pungency in onions and garlic with units of μmol/gfw (micromoles per gram fresh weight).
[1] 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.
[citation needed] The HoneySweet brand onion is claimed to consistently rate with a pungency level of 3.5 or less.
[2] The Supasweet onion (usually grown in Lincolnshire, England) registers 1.5 to 2 on the scale.
Soil type, rain, and sunlight affect the pungency in onions and garlic and, therefore, their score on the pyruvate scale.