Pine nuts, which are popular in both recipes and on their own, are seeds produced by several species of the genus Pinus, and have been used as food by indigenous cultures and contemporary societies.
Food Standards Australia New Zealand has investigated consumer reports of a bitter, metallic taste resulting from eating pine nuts.
This aftertaste is sometimes referred to by consumers as ‘pine mouth’ and can last for a number of days or weeks and can result from eating raw, cooked and processed pine nuts.
However, apart from the unpleasant bitter aftertaste, there are no safety issues that can be identified at this time. For sufferers, the condition is apparently self-limiting (it resolves itself) and is relatively benign without any ongoing adverse effects.
There has also been no evidence to date that the taste disturbances associated with pine nuts are the result of external contamination (Mostin, 2001).
There is ongoing research on the subject and there is recent speculation that symptoms may be related to lipid decomposition (Miraliakbari & Shahidi, 2008) or species differences with the fatty acid profiles (Destaillatset al, 2010) of the pine nuts.
The International Nut and Dried Fruit Council has announced efforts to improve the quality of pine nuts for consumers, by the selection of suitable species and industry certification.
In June 2012 the New South Wales Food Authority published an issues paper on pine nuts. The paper includes a summary of case studies and details about the most recent research into this issue.