Shogaols are
pungent
Pungency ( ) is 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 lower ...
constituents of
ginger
Ginger (''Zingiber officinale'') is a flowering plant whose rhizome, ginger root or ginger, is widely used as a spice and a folk medicine. It is an herbaceous perennial that grows annual pseudostems (false stems made of the rolled bases of l ...
similar in chemical structure to
gingerol. The most common of the group is
shogaol. Like
zingerone, it is produced when ginger is dried or cooked.
Moreover, shogaol (and
gingerol) are converted to other constituents when heat is applied over time, which is why ginger loses its spiciness as it is cooked.
The name ''shogaol'' is derived from the
Japanese name for ginger (生姜、''shōga'').
Shogaol is rated 160,000 SHU on the
Scoville scale
The Scoville scale is a measurement of spiciness of chili peppers and other substances, recorded in Scoville heat units (SHU). It is based on the concentration of capsaicinoids, among which capsaicin is the predominant component.
The scale ...
.
When compared to other pungent compounds, shogaol is moderately more pungent than
piperine, but 100 times less than
capsaicin
Capsaicin (8-methyl-''N''-vanillyl-6-nonenamide) (, rarely ) is an active component of chili peppers, which are plants belonging to the genus ''Capsicum''. It is a potent Irritation, irritant for Mammal, mammals, including humans, and produces ...
.
Shogaols group
Shogaol,
shogaol,
0shogaol, and
2shogaol (all found in ginger) together constitute the group shogaols. There also exist in ginger cultivars methylated shogaols: methyl
shogaol and methyl
shogaol, respectively.
Shogaols are artifacts formed during storage or through excess heat, probably created by a
dehydration reaction
In chemistry, a dehydration reaction is a chemical reaction that involves the loss of an H2O from the reacting molecule(s) or ion(s). This reaction results in the release of the H2O as water. When the reaction involves the coupling of two molecu ...
of the gingerols. The ratio of shogaols to gingerols sometimes is taken as an indication of product quality.
[ NSF International ''Determination of Gingerols and Shogaols in Zingiber officinale rhizome and powdered extract by High-Performance Liquid Chromatography'' ]
Synthesis
A possible synthesis starts with a
Claisen condensation of
vanillin
Vanillin is an organic compound with the molecular formula . It is a phenolic aldehyde. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the ethanolic extract of the vanilla bean. Synthetic vanillin ...
and
acetone
Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...
, producing dehydrozingerone. Afterwards the product reacts in an
aldol condensation with
hexanal in
tetrahydrofurane to 6-dehydroshogaol and 6-dehydrogingerol. Latter can be
hydrogenated to
gingerol by a catalyst. In the last step
hydrochloric acid
Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...
is added to get the desired
shogaol.
References
{{Transient receptor potential channel modulators
Pungent flavors
O-methylated natural phenols
Ginger