Pine Nut - Physical Characteristics

Physical Characteristics

Pine nuts contain, depending on species, 10–34% protein, with Stone Pine having the highest content. They are also a source of dietary fiber. 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 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 (−5 °C (23 °F) to 2 °C (36 °F)); 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, can have poor flavour and may be already rancid at the time of purchase. Consequently, pine nuts are often frozen to preserve their flavour.

European pine nuts may be distinguished from Asian ones by their greater length in comparison to girth; Asian pine nuts are stubbier, shaped somewhat like long kernels of corn. The American pinyon nuts are known for their large size and ease of shelling. In the United States, P. edulis, the hard shell or New Mexico and Colorado, became a sought-after species due to the Trading Post System and the Navajo people who used the nuts as a means of commerce. The Italian pine nut, (P. pinea) was brought to the United States by immigrants, and became a favored treat along the East Coast until the early 1930s, when bumper crops of American pine nuts were readily available at low prices.