The pyruvate scale measures pungency in
onions
An onion (''Allium cepa'' L., from Latin ''cepa'' meaning "onion"), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the on ...
and
garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northeas ...
with units of
μmol/g
fw (micromoles per gram fresh weight).
It is named after
pyruvic acid
Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell.
Pyruvic aci ...
, the
alpha-keto acid
In organic chemistry, keto acids or ketoacids (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group () and a ketone group ().Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in Ullmann's En ...
co-product created in the biochemical pathway that forms
''syn''-propanethial-''S''-oxide, the main
lachrymatory
Lachrymatory or lacrymatory may refer to:
* Something that has the effect of ''lachrymation'', causing the secretion of tears
* Tear gas
Tear gas, also known as a lachrymator agent or lachrymator (), sometimes colloquially known as "mace" af ...
agent in onions.
Examples
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/g
fw or less. The Supasweet onion (usually grown in
Lincolnshire
Lincolnshire (abbreviated Lincs.) is a Counties of England, county in the East Midlands of England, with a long coastline on the North Sea to the east. It borders Norfolk to the south-east, Cambridgeshire to the south, Rutland to the south-we ...
,
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
) registers 1.5 to 2 on the scale. A standard brown onion is usually in the range of 6–7 out of 10.
Influential factors
Soil type, rain, and sunlight affect the pungency in onions and garlic and, therefore, their score on the pyruvate scale.
See also
*
Scoville scale
The Scoville scale is a measurement of the pungency (spiciness or "heat") of chili peppers, as recorded in Scoville heat units (SHU), based on the concentration of capsaicinoids, among which capsaicin is the predominant component.
The scale i ...
References
External links
The National Organic Program— by the
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of comme ...
Scales
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