Earlier this year while looking for new smoothie ideas online I came across the notion of soaking nuts. Raw foodists who eat a lot of nuts are particularly big proponents. The claim is that by soaking nuts and discarding the soak water you can increase the digestibility and nutritional value of nuts. I decided to try it and see what soaked nuts are like. The standard practice is to first soak them and then dehydrate them. When I tried this with walnuts I found that the taste was dramatically altered. They retain a distinct walnut flavor, but they lose the mouth-puckering astringency of raw walnuts. I’ve found that the loss of astringency makes them a better smoothie ingredient. See the end of the post for details of the soaking process.
I have not noticed the same sort of dramatic flavor change with almonds. One thing about almonds though is that similar to blanching them, soaking loosens their skin, and you can pop them out of it if you so desire. Sometimes I do that if I want a slightly less fibrous ingredient, though it’s a bit labor intensive. I used some peeled almonds in the tri-berry smoothie from last week.
I have also soaked pecans, which came out deliciously, although I didn’t save any unsoaked ones to make a direct comparison. Update: I’ve since made a comparison, and I preferred the flavor of soaked and dried pecans over an unsoaked pecan from the same batch.
In terms of nutrition, unfortunately I have not found any solid scientific studies that indicate soaking makes a difference. One of the main concerns is phytic acid, which can bind to minerals and prevent them from being absorbed, though it seems that this is only a serious problem for malnourished people. Furthermore, I have not found any measurements of phytic acid before and after soaking. Another possibility of concern is tannins. In this case we can actually taste the difference with walnuts, as their unsoaked astringency is attributed to tannins. However, it is not clear that the tannin levels in the unsoaked nuts are a nutritional problem.
Most of these lines of reasoning seem to trace back to the Weston Price Foundation, and their food bible, Nourishing Traditions. I haven’t had a chance to look at a copy of it yet, but I’ve gotten some idea of it from reading online. The strongest arguments I’ve found are ones that cite old traditions of soaking nuts (including from pre-Columbian Central Americans, and Indian Ayurveda).
If anyone knows of any solid references regarding soaking nuts, I’d love to see them. At some point I’m going to check out Nourishing Traditions to see if it has any further details, and I will post an update if I find any compelling evidence. In the meantime I will continue to soak walnuts when I have time because I like the way they taste.
This is is my nut soaking protocol (based on what I found on blogs, such as this one):
1) For each half pound of nuts, dissolve two tablespoons of salt in a quart of water. This approximates the salinity of seawater:
2tbsp salt ≈ 35 grams and 1 quart ≈ 1 liter = 1000 grams,
35 grams salt per 1000 grams water, is 3.5% salinity; roughly the salinity of the ocean.
2) Put nuts in a bowl and cover with the salt water–they should be well covered with plenty of extra water. Cover bowl with a plate and leave for ~8hrs.
3) Drain nuts in a colander and rinse.
4) Dehydrate. Serious raw foodists have purpose-built food dehydrators for this task, but I found my gas oven on its lowest setting to work perfectly well. I spread the nuts out on cookie sheets and left them in the oven for 12-24 hours. I was surprised to find that on the low setting the oven stays around 120F. The Nourishing Traditions folks suggest that an oven temperature of up to 150F should be fine. They’re done when they’re completely dried out.
5) After cooling, I like to put them in a jar and store them in the freezer. That way they keep for a really long time, and they cool off the smoothie a bit when I add them.