Pines (genus: Pinus) are an evergreen group of coniferous seed plants consisting of approximately 100 species and numerous varieties and hybrids. Different species of pines vary greatly in numerous ways such as (1) seed productivity and commercial uses; (2) seed characteristics such as fatty acid profile, size, shape and colour; (3) nutritional and medicinal value; and (4) taste and textural properties. Despite these differences, they are all merged under the generic name of ‘pine nuts’ when retailed.
Approximately 20 species produce economically viable edible seeds for consumption, of which only P. koraiensis, P. sibirica, P. pinea and P. sibirica are known to be internationally important for their edible seeds. There are, however, other species of pine nuts that are consumed locally where they are being produced.
China has a rich pine flora and produces many species of pine nuts apart from P. koraiensis and P. sibirica. In addition, the Chinese processing plants (where pine nuts are shelled and sorted) also import un-shelled pine nuts from the neighbouring countries of Korea and Russia, then process and re-export them as Chinese pine nuts. The case of Trader Joe’s pine nuts being a ‘product of Russia and/or Korea’ is moot, as 7 samples of Trader Joe’s pine nuts collected contained the same compositional mixture of P. koraiensis, P. sibirica and P. armandii pine nuts (the last of which is responsible for the taste disturbance).
Based on collected reference species, botanical descriptions, physical measurements and industry information, I have identified 8 different commercial species of pine nuts, of which 6 of them are of Chinese origins, 1 from the Himalayan region (G) and 1 from the Mediterranean region (P). These 8 species are shown in the picture below, and the table includes a description of my observations and physical measurements I have performed. Except for U2, the rest were found in at least 1 of the complaint samples received.
Of the 6 Chinese species (A, K, S, M, U1, U2), only A (P. armandii) was found to consistently cause PNS. K (P. koraiensis) and S (P. sibirica) are the good ones that have long been established on the market. These two species also grow in regions of Russia and Korea. The visual differences between the species are rather clear, hence, with a little attention, you could avoid pine mouth! Below’s a guide with more specific descriptions to aid in your identification of the different pine nuts!