Sinalbin is a

glucosinolate Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise damage ...

found in the seeds of white mustard, '' Sinapis alba'', and in many wild plant species. In contrast to mustard from black mustard (''

Brassica nigra ''Brassica nigra'', or black mustard, is an annual plant cultivated for its dark-brown-to-black seeds, which are commonly used as a spice. It is native to tropical regions of North Africa, temperate regions of Europe, and parts of Asia. Desc ...

'') seeds which contain

sinigrin Sinigrin is a glucosinolate that belongs to the family of glucosides found in some plants of the family Brassicaceae such as Brussels sprouts, broccoli, and the seeds of black mustard (''Brassica nigra''). Whenever sinigrin-containing plant tis ...

, mustard from white mustard seeds has only a weakly

pungent Pungency () refers to the taste of food commonly referred to as spiciness, hotness or heat, found in foods such as chili peppers. Highly pungent tastes may be experienced as unpleasant. The term piquancy () is sometimes applied to foods with a l ...

taste. Sinalbin is metabolised to form the mustard oil 4-hydroxybenzyl

isothiocyanate In organic chemistry, isothiocyanate is the functional group , formed by substituting the oxygen in the isocyanate group with a sulfur. Many natural isothiocyanates from plants are produced by enzymatic conversion of metabolites called glu ...

by the enzyme

myrosinase Myrosinase (, ''thioglucoside glucohydrolase'', ''sinigrinase'', and ''sinigrase'') is a family of enzymes involved in plant defense against herbivores, specifically the mustard oil bomb. The three-dimensional structure has been elucidated and is ...

. The less sharp taste of white mustard is because 4-hydroxybenzyl isothiocyanate is unstable and degrades to

4-hydroxybenzyl alcohol Gastrodigenin is a phenolic compound found in the rhizome of '' Gastrodia elata''. Gastrodin is the glucoside A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced ...

and a

thiocyanate ion Thiocyanate (also known as rhodanide) is the anion . It is the conjugate base of thiocyanic acid. Common derivatives include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) thiocyanate was formerly used in pyrot ...

, which are not pungent. The half-life of the isothiocyanate depends on the pH of the solution – the longest time is 321 minutes at pH 3, and the shortest is 6 minutes at pH 6.5. Glucobrassicin is a structurally related glucosinolate that likewise yields a non-pungent isothiocyanate due to reaction with water.

References

{{Reflist Pungent flavors Nutrition Glucosinolates Phenols