Friday, September 07, 2007

Mysteries of Prunus REVEALED!!!

My own thought a day

Inspired by my old high school friend Ben (WARNING: no rewilding content!), I embark on an attempt to post once a day with some tidbit concerning permaculture, rewilding, the collapse of civilization, or some such important piece of my life. I have never posted as often to this blog as I would like, nor have I ever emailed or called friends and family as often as I intended, so I don't feel particularly hopeful about my commitment to daily posting. (I don't recommend that you put any money down on it!) But I'll try to give it a good shot, and if it means I wind up posting once a week, at least I'll be posting more often than the once a month I've managed thus far! So...

Prunus presents

I now reveal the secrets of Prunus! Learn how to double the value of your prunes! Meet the mystery fruit, once hated as a useless pain in the ass, now my beloved companion!

Kernel of wisdom

As you know, botanists classify almonds in the genus Prunus, along with many of our common fruits including plums, cherries, peaches, and apricots. People grow almonds for their extra-large seed enclosed in (if I understand correctly) a thin layer of flesh which pretty much dries up and withers away once the almond ripens. The seed, when cracked open, reveals an...almond...a nice large package of nut!

According to Plants for a Future, you can eat the kernels of the seeds of just about all other Prunus species in the same way as almonds. Some cautions apply: "sweet" almonds cultivated for eating come from a type of almond species selected for low content of the glycoside amygdalin, "which becomes transformed into deadly Prussic acid (Hydrogen cyanide) after crushing, chewing, or any other injury to the seed." (Wikipedia) Wild, or bitter almonds, contain relatively high amounts of amygdalin and thus pose more danger of cyanide poisoning upon ingestion. Other Prunus species have varying levels of amygdalin, and content may even vary across individuals within a species. The more amygdalin, the more bitter the taste. So if a kernel tastes "too bitter" (PFAF's phrase--I'm not quite sure how to judge that!), avoid it! Again according to PFAF, "[amygdalin leading to hydrogen cyanide] is usually present in too small a quantity to do any harm but any very bitter seed or fruit should not be eaten. In small quantities, hydrogen cyanide has been shown to stimulate respiration and improve digestion, it is also claimed to be of benefit in the treatment of cancer. In excess, however, it can cause respiratory failure and even death."

I have heard second-hand (and therefore pass it along merely as rumour for you to evaluate yourself), that John Kallas (whom I perceive as responsibly anal when it comes to researching and making statements about foods with potential toxicity) says that since hydrogen cyanide is a gas at room temperature, that by crushing or cutting up kernels you can convert the amygdalin into hydrogen cyanide which evaporates off, therefore reducing or eliminating the dangers of eating kernels. I don't know how long you have to wait for the gas to evaporate, or how thoroughly you should crush or cut the kernels. Note that wikipedia seems to describe hydrogen cyanide as a gas only above 78.8°F, although other sources I found with a random web search state it a gas at "room temperature."

This seems consistent with citations I've seen in Daniel Moerman's Native American Ethnobotany and in Samuel Thayer's The Forager's Harvest that Native Americans pounded up various small Prunus fruits, fruit shell and kernel, then dried them as cakes for later consumption. I believe Moerman's book also mentions roasting or leaching as methods used to process Prunus kernels (or maybe I saw that in another source, or maybe I made it up). I generally figure indigenous people knew what they were doing, so this seems like good confirmation to me of the safety of consuming kernels in moderation, especially if processed in any of those ways. (Though I have to say that eating dried fruit with little bits of shell mixed in does not sound appealing to me.)

For the last month or two I have been eating kernels from cherries, plums, and a few peaches. I have eaten maybe 12 kernels per day on average, probably eating no more than 40 kernels on any given day. I have felt no ill effects, aside from mild frustration at the low yield! Cracking peach pits seems to give an equivalent yield for time invested to other nuts, but since cherry and plum pits give much less nut meat per seed, it takes a lot of hammer whacks and (most time-consuming) fiddling with the cracked seed to extract enough kernels to equal, say, one walnut. (I think I'll post a fuller comparison of nuts yields and so on at some point). Given that I do not have access to foraged almonds, I don't mind spending a little extra time (which can feel meditative--I like hitting things with hammers) to add variety to my usual walnuts & cashews with almond-tasting morsels. And I really enjoy the way this discovery extends the caloric and nutritional value of all these fruits we've foraged...I misled you above by saying you could double the value of your Prunus, but as a wild-ass-guess the kernels may yield 25% again of the calories of the fruit flesh, well worth capturing and eating if you have time to spare.

Enough for'll have to tune in tomorrow for the exciting conclusion to our unique expose on PRUNUS!!!


FarmerScrub said...

I forgot to mention a few things:

As with any potentially toxic foods, Prunus kernels may harm children in smaller doses than would harm adults, so exercise extra caution.

I have been eating my Prunus kernels either raw upon first cracking them, or after soaking them overnight with other nuts. When I crack them, in the process I split or slightly crush some of the kernels, but probably the majority of kernels crack out whole and undamaged. I do not deliberately or systematically crush any kernels, so I have not really made use of the hydrogen cyanide gas theory to reduce my exposure to potential toxicity.

I have the feeling I thought of one other addition I wanted to make, but I can't remember it now, so I may post another follow-up comment in the future.

Anonymous said...

Hey Norris

The amygdalin content of the prunuses (prunii?) is also why the leaves are toxic to sheep and goats. I guess when the leaves are fresh, they're only mildly toxic, but once they wilt, it concentrates the toxins, or something, and over they go.

Glad you're posting again....


FarmerScrub said...

Hey Rich,

Thanks for visiting! Yeah, the leaves of most or all Prunusiieuses contain that tricky another use for laurels is to make a condiment. From PFAF: "Water distilled from the leaves is used as an almond flavouring. It should only be uses in small quantities, it is poisonous in large amounts." One of my other sources says the same thing, with emphasis on the danger of overdosing. Since I don't feel a particular need for almond-flavored water with presumably negligible calories and which might hurt me if I use too much of it, I don't plan to experiment with that aspect of it...