Almond (Prunus dulcis [Mill.] D. A. Webb.)

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Sweet almonds, hulled

Used plant part

The soft interior of the fruit stone (embryo).

Plant family

Rosaceae (rose family), subfamily Prunoidae.

Sensoric quality

Sweet almond have a faint, nutty fragrance and taste; bitter almonds taste strongly bitter and develop an intensive, characteristic aroma with moisture (e.g., by chewing).

Main constituents

Almonds (bitter as well as sweet) contain about 50% of a fat oil, which is, though, too expensive to be used for cooking. It is made up of glycerides (80% oleic acid, 15% linoleic acid, 5% palmitic acid).

Bitter almonds

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 enzymatical hydrolysis of these glycosides by beta-glucosidases, the aglycon mandelic nitrile (2-hydroxy-3-phenylacetonitrile) is liberated. A second enzyme (mandelonitrile lyase) converts mandelic nitrile quickly to benzaldehyd (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 benzaldehyd.

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 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.
 

Almond flower www.botanikus.de

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 desactivated 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.
 

Ripening almond fruits www.botanikus.de

Origin

The origin of almonds is variously given as West or Central Asia; almonds have been cultivated in the Mediterranean region since more than 2000 years, as can be proven from the numerous references to almonds in the Old Testament (see pomegranate).

Today, the most important producers for the European market are Spain and Italy. Californian almonds are of increasing importance.

Etymology

Almonds' names in all European tongues essentially derive from Greek amygdálee or amýgdalos "almond", whose origin is not known. The element al- got attached to the English and Spanish names by confusion with the prefix al-

Almond branch with flowers www.mpiz-koeln.mpg.de

in many Arabic loan words found in Romance tongues; see also caper on this topic.

The botanic genus name, Prunus, is derived from the Latin name of the closely related plum, prunum, which in turn goes back to Greek proûnos. The species name, dulcis "sweet" is motivated by the kernel's taste; bitter almonds are considered a variety (var. amara), where Latin amarus means "bitter".
 

 

Sweet almonds are much used in Near and Middle Eastern cuisine; in Northern Indian cooking style, which was heavily influenced by Persia, they are widely used, besides poppy seeds, as a sauce thickener (in whole India, wheat flour is never taken for this purpose). Typically, almonds are fried together with several spices (mace, cinnamon, cumin and garlic or ginger) and then quenched with yoghurt.

Almond pieces browned in butter fat (ghee) are a popular, aromatic decoration for fragrant biriyanis or other dishes of meat with dried fruits. Some Indian desserts also contain almonds, e.g. badaami kheer, an almond pudding flavoured with saffron. For a fuller account of the Persia-influenced cuisine of Northern India (moghul cooking), see black cumin.

The most famous product of Western cuisine containing almonds is marzipan (also spelled marchpane). This confection is basically an intensively kneaded mixture of ground almonds, sugar and aromatic essences, frequently rose water. For this recipe, sweet almonds are either used alone or flavoured with one or two bitter almonds per 100 g of sweet almond; you might also try just a hint of bitter almond essence).

Since bitter almonds are toxic, they are sometimes hard to get in Western countries, owing to paternistic laws; bitter almond essence is, then, the only way to archive bitter almond aroma. This essence is won by distilling a mixture of ground bitter almonds and water; it is more or less pure benzaldehyd, containing no hydrocyanic acid. Almond essence is well-suited to flavour cookies, cakes and marzipan. Since it is very strong, care must be taken not to overdose. If not available, kernels of peach or apricot can also be tried. Another possible substitute for bitter almonds are tonka beans in small dosage; yet also this spice may be not altogether harmless.

Bitter almonds' usage in kitchen is mostly limited to sweets. They can, though, be used to flavour spicy dishes, thus giving a very exotic taste. Careful dosage is essential and requires a lot of skill or practise. You may try them, for example, for Chinese fried pork (that's not my idea, but Stobart's).