Bitter Almonds Regarding Amygdalin

[Guest guest]

Bitter almonds contain 3 to 5% amygdalin, a so-called cyanogenic glycoside

composed of mandelic nitrile and gentobiose. Vegetative parts of the almond tree

accumulate the analogous prunasin (with glucose as sugar component). On

enzymatic hydrolysis of these glycosides by ß-glucosidases, the aglycon

mandelic

nitrile (2-hydroxy-3-phenylacetonitrile) is liberated. A second enzyme

(mandelonitrile lyase) converts mandelic nitrile quickly to benzaldehyde

(C6H5–CHO) and

hydrocyanic acid (HCN, also known as prussic acid). By chance, both compounds

are olfactorily similar, but hydrocyanic acid is highly toxic; bitter

almonds' value as a spice is only due to the benzaldehyde.

Hydrocyanic acid is a dangerous poison (about one twentieth of a gram is

considered lethal for an adult), but it is also very volatile and susceptible to

hydrolysis at higher temperatures. Therefore, significant amounts of

hydrocyanic acid are highly unlikely to accumulate in any dish prepared with

bitter

almonds. On the other side, incorporation of whole raw bitter almonds is fairly

dangerous because, in this case, all of its hydrocyanic acid is formed in one's

stomach. Serious poisoning is quite rare with adults, but children may be

killed by just a few bitter almonds. Very similar warnings hold for other plants

of the genus <I class=bot lang=la>Prunus, the kernels of which all contain

amygdalin: Peach, apricot and, to a lesser extent, cherry and plum. One kernel

of

bitter almond yields about one milligram of hydrocyanic acid. It should be

noted that bitter almonds can only develop their aroma if both water and the

necessary enzymes are present. The two enzymes (called together emulsin) are

deactivated by heat; thus, bitter almonds must never be fried nor roasted, for

they

will not develop almond aroma afterwards.Sweet almonds are, by centuries of

cultivation and breeding, very low in amygdalin and, thus, harmless; however,

even sweet almond trees sometimes yield single bitter almonds (up to 1% of

total crop), and some sweet almond cultivars still contain traces of bitter

almond

aroma. This does not apply to Californian almonds, which can be regarded

totally destitute of amygdalin.Principally, sweet and bitter almonds are very

different products and can never substitute each other.