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Stone Pine cone with pine nuts - note two nuts under each cone scale
Stone Pine cone with pine nuts - note two nuts under each cone scale

Pine nuts are the edible seeds of pines (family Pinaceae, genus Pinus). About 20 species of pine produce seeds large enough to be worth harvesting; in other pines the seeds are also edible, but are too small to be of value as a human food.[1][2][3]

 

 Species and geographic spread

In Europe, pine nuts come from the Stone Pine (Pinus pinea), which has been cultivated for its nuts for over 6,000 years, and harvested from wild trees for far longer. The Swiss Pine (Pinus cembra) is also used to a very small extent.

In Asia, two species are widely harvested, Korean Pine (Pinus koraiensis) in northeast Asia (the most important species in international trade), and Chilgoza Pine (Pinus gerardiana) in the western Himalaya. Four other species, Siberian Pine (Pinus sibirica), Siberian Dwarf Pine (Pinus pumila), Chinese White Pine (Pinus armandii) and Lacebark Pine (Pinus bungeana), are also used to a lesser extent.

In North America, the main species are three of the pinyon pines, Colorado Pinyon (Pinus edulis), Single-leaf Pinyon (Pinus monophylla), and Mexican Pinyon (Pinus cembroides). The other eight pinyon species are used to a small extent, as are Gray Pine (Pinus sabineana), Torrey Pine (Pinus torreyana) and Sugar Pine (Pinus lambertiana). In the United States, pine nuts are mainly harvested by Native American tribes; in many areas, they have exclusive rights to the harvest.

 Ecology and status

In the United States, millions of hectares of productive pinyon pine woods have been destroyed due to conversion to grazing lands, and in China, destructive harvesting techniques (such as breaking off whole branches to harvest the cones) and the removal of trees for timber have led to losses in production capacity.[2]

Physical characteristics

Pine nuts contain (depending on species) between 10–34% protein, with Stone Pine having the highest content.[2] They are also a source of dietary fibre. When first extracted from the pine cone, they are covered with a hard shell (seed coat), thin in some species, thick in others. The nutrition is stored in the large female gametophytic tissue that supports the developing embryo (sporophyte) in the centre. Although a nut in the culinary sense, in the botanical sense pine nuts are seeds; being a gymnosperm, they lack a carpel (fruit) outside.

The shell must be removed before the pine nut can be eaten. Unshelled pine nuts have a long shelf life if kept dry and refrigerated (at –5 to +2 °C); shelled nuts (and unshelled nuts in warm conditions) deteriorate rapidly, becoming rancid within a few weeks or even days in warm humid conditions. Pine nuts are commercially available in shelled form, but due to poor storage, these rarely have a good flavour and may be already rancid at the time of purchase.

European Stone Pine nuts (Pinus pinea) to be compared with the picture below
European Stone Pine nuts (Pinus pinea) to be compared with the picture below
Korean Pine (Pinus koraiensis) pine nuts - unshelled, and shell, above; shelled, below
Korean Pine (Pinus koraiensis) pine nuts - unshelled, and shell, above; shelled, below

Culinary uses

Pine nuts have been eaten in Europe and Asia since the Paleolithic period. They are frequently added to meat, fish, and vegetable dishes. In Italian they are called pinoli or (rarely) pignoli[4] and are an essential component of Italian pesto sauce. The pignoli cookie, an Italian specialty confection, is made of almond flour formed into a dough similar to that of a macaroon and then topped with pine nuts. Pine nuts are also featured in the salade landaise of southwestern France. Pine nut coffee, known as piñón (Spanish for pine nut), is a speciality found in the southwest United States, especially New Mexico, and is typically a dark roast coffee having a deep, nutty flavour; roasted and lightly salted pine nuts can often be found sold on the side of the road in cities across New Mexico to be used for this purpose. Pine nuts are also used in chocolates and desserts such as baklava. It is also a widely used ingredient in Middle Eastern cuisine, reflected in a diverse range of dishes such as kibbeh, sambusek, ladies' fingers and many others.

Throughout Europe and Middle East the pine nuts used are from Pinus pinea (Stone Pine). They are easily distinguished from the Asian pine nuts by their more slender shape and more homogeneous flesh. Due to the lower price, Asian pine nuts are also often used, especially in cheaper preparations.

 Risks of eating pine nuts

The eating of pine nuts can cause serious taste disturbances, lasting for days or weeks. The taste disturbance developes one or two days after consumption. A bitter, metallic taste is described. The pine nuts involved are always imported from China, but only a minority of Chinese pine nuts present this problem. Until now it is not clear which pine species is implicated. Concerning the cause, it has been observed that the pine nuts involved typically contain triglycerides, formed by 16-18° unsaturated fatty acids. Analysis on pesticide residus and heavy metal did not reveal any contamination.[5]. Though very unpleasant, there doesn't seem to be a real health concern. The problem can be avoided by not consuming Chinese pine nuts. They can be recognised because they are shorter.

 Pine nut oil

Main article: Pine nut oil

Pine nuts can be pressed to extract pine nut oil, which is valued both for its mild, nutty flavour and its health benefits such as appetite suppression[6] and antioxidant action.


 Other similar seeds

The large edible seeds of species of the Southern Hemisphere conifer genus Araucaria, notably Araucaria araucana (Pehuén) of Chile, Araucaria bidwillii (Bunya) of Australia and Araucaria angustifolia (Parana pine) of Brazil, are also often called, although improperly, pine nuts.

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