Pyruvate scale
Encyclopedia
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 the lacrimator, syn-Propanethial-S-oxide
.
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.
Mole (unit)
The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities as there are atoms in 12 grams of pure carbon-12 , the isotope of carbon with atomic weight 12. This corresponds to a value...
/gfw (micromoles per gram fresh weight). It is named after pyruvic acid
Pyruvic acid
Pyruvic acid is an organic acid, a ketone, as well as the simplest of the alpha-keto acids. The carboxylate ion of pyruvic acid, CH3COCOO−, is known as pyruvate, and is a key intersection in several metabolic pathways....
, the alpha-keto acid co-product created in the biochemical pathway that forms the lacrimator, syn-Propanethial-S-oxide
Syn-propanethial-S-oxide
syn-Propanethial S-oxide is a gas that acts as a lachrymatory agent . The chemical is released from onions, Allium cepa, as they are sliced...
.
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
Lincolnshire
Lincolnshire is a county in the east of England. It borders Norfolk to the south east, Cambridgeshire to the south, Rutland to the south west, Leicestershire and Nottinghamshire to the west, South Yorkshire to the north west, and the East Riding of Yorkshire to the north. It also borders...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
) 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.
External links
- The National Organic Program — by the USDA