Sci got the fodder for this week's Friday Weird Science via Anne Jefferson of the Highly Allocthonous blog. Apparently Anne recently suffered a doozy of an episode of...pine nut mouth.
What, you've never heard of it?
Neither had I until this came along last week. But it's a real phenomenon, and apparently a really disgusting downer for those who have suffered from it.
Pine nut mouth is an odd case of dysgeusia, or disruption of the sense of taste. Usually you are making pesto or something else delicious with pine nuts, nom on a few, and think nothing of it. Maybe you just nom on them anyway. But the weird thing happens up to two days later, when suddenly...everything tastes funny. Not just funny, BAD. Things become oddly bitter, or even have kind of a soapy flavor. Your morning coffee? Ick. A piece of toast? Gross. Fed up and just want a drink? Disgusting. NOTHING gets the flavor out. Though this usually lasts only a few days, some people suffer effects for one to two WEEKS.
But there's very little out there on the subject of pine nut mouth. There are several blogs (this one in particular is a pretty good source) but relatively few actual papers on this. This is possibly because it's not often reported (most people wouldn't report dysgeusia as a medical problem anyway, and often it probably goes away before people seek help for it), but also for one rather good reason; it's not known to be HARMFUL. Disgusting? You bet. Annoying? Absolutely. Harmful? Meh.
But it IS a kind of a funny mystery. I mean 9 times out of ten you eat pine nuts and you're fine! Sci has eaten pine nuts many a time in her life (mmmm...pesto....mmmmmmmm), and never even had this happen once. So what's the DEAL!?
They look so innocent...
Destaillats, et al. "Identiﬁcation of the Botanical Origin of Commercial Pine Nuts Responsible for Dysgeusia by Gas-Liquid Chromatography Analysis of Fatty Acid Proﬁle" Journal of Toxicology, 2011.
And I dedicate this post to Anne Jefferson of the Highly Allocthonous blog, who I hope has her sense of taste back intact by now. Want a post dedicated to yourself? Well, have a weird problem, and we'll talk.
Pine nuts have been a part of cuisine in Europe and Asia since, well...since forever. Like the paleolithic period. They have lots of uses other than pesto (though pesto may be, in my opinion, the most delicious) including using them with fish or meat, baking them into sweets like biscotti or baklava, and even using it in coffee. They are high in protein, and generally pretty tasty (to be honest, they taste, well, nutty).
But here's the thing about pine nuts. You can't GROW THEM. Or rather, you could, but no one really has the patience to cultivate the crop. A good pine nut can take 18 MONTHS to mature, and honestly, pines are just everywhere, you know? They are things that grow easily in the wild and produce pretty well, so most pine nuts are still collected relatively wild. And this means that it's difficult to really say WHICH pine nuts you're eating. There are over 20 varieties of pine that produce edible nuts, and they all look awfully similar.
So the question becomes, do the people who get this pine nut mouth have (a) sensitivity to pine nuts? (b) eaten a bad set of pine nuts that rotted or something? (c) ate a set of pine nuts with specific things IN them, like pesticides? (d) or is it a specific VARIETY of pine nut that isn't particularly tasty...one to two days after you've eaten it. (a) doesn't seem very likely, many of the people had eaten pine nuts for years prior, and CONTINUED to eat pine nuts afterward, and were fine. So it's down to (b), (c), or (d).
This is a problem for the toxicologists!! Why toxicologists? Mostly because they are the ones who get the reports of this problem, as people tend to be more likely to go to poison control about the taste issues than go to their doctor. Presumably they've been collaborating with some botanists and chemists as well. The other reason you call in the toxicologists is because, when people go to poison control, they are often instructed to bring the offending item WITH THEM. So a toxicologist is going to collect samples of things. In this case, of pine nuts.
The poison center in Belgium got 15 different samples from people who complained of pine nut mouth (ok, they got a spontaneous sample from New Zealand, I guess he got wind of the study and felt New Zealand wasn't taking him seriously). They then looked at the composition of the samples, whether they were past expiration date, and what they contained. This quickly solved problem (b), all of the nuts were still good. This leaves the question of whether it was an outside influence, or whether they had some bad nuts. The outside influence (c) seems a little unlikely. Pine nuts are currently distributed all over the world, and due to the fact that they aren't farmed, it's less likely for them to be sprayed with pesticides. There could be differences in the soil, but often you'll get one batch from asia that's fine, and another that's not. Still, well worth testing.
So the scientists ground up the pine nuts and analyzed them for fatty acid content. They also carefully went through each pile of pine nuts and looked at all the different varieties in there, checking where they'd come from.
And here was where the pattern emerged. While the samples were shipped in from Belgium, France, the Netherlands, and New Zealand, they didn't contain pine nuts from those areas. Rather, they contained pine nuts from ASIA. Some said China, and one even said Siberia, which wasn't exactly helpful (Siberia isn't a country, it's a region that is most of northern Asia, and makes up 77% of Russia's landmass. It is COMPLETELY HUGE. Not helpful). But they noticed that the pine nuts were never all one variety, they were usually two or more. And the one constant across ALL the pine nut mouth samples was one variety: Pinus armandii, a pine nut from China.
The authors think (and other scientists who study this agree with them) that this particular subspecies is problem, and that specific characteristics of the nut cause its fatty acids to react badly with your mouth, causing a major messup in taste (though the mechanism still isn't known).
And this is great, right? You can go in, find which are the bad ones, and pick them out!
You see? The one on the left is P armandii, while the one on the right is the safe, tasty P koraiensis . It's so obvious. I mean, one is small and round and beige, and the other is...small and round and beige...
Oh who am I kidding, if they didn't tell me in the paper I'd have no clue. I mean, couldn't they just dye the bad ones green or something???
You can apparently compare them though.
The one on the top there is the Asian nut, and the one on the bottom is European. But that doesn't really take out P armandii specifically. So right now the scientists think the best course of action is for pine nut collectors and distributors, who KNOW what the right ones look like, to just weed out the wrong ones. In the meantime, they are still looking for WHY these nuts mess with your sense of taste. I admit I really want to know!!
There's a big pine nut blog here. She agrees with the researchers about P armandii, and thinks the safest course (and she's probably right) is to buy European pine nuts rather than Asian. The European ones are more expensive, but if you love pine nuts, they are probably worth it. Or, you can hazard your chances, and if tragedy strikes, know that you're in for one to two weeks of a very nasty aftertaste.
Destaillats, F., Cruz-Hernandez, C., Giuffrida, F., Dionisi, F., Mostin, M., & Verstegen, G. (2011). Identification of the Botanical Origin of Commercial Pine Nuts Responsible for Dysgeusia by Gas-Liquid Chromatography Analysis of Fatty Acid Profile Journal of Toxicology, 2011, 1-7 DOI: 10.1155/2011/316789