Cooking Challenge | Have you tried processing and eating fresh green Black Walnut fruit?

The edible fruit of the Black Walnut tree, Juglans nigra, is harvested in mid-to-late June while it is still green and before the shell inside begins to harden.

You think I'm crazy? Here's crazy: That fruit has something like 50–70 times as much Vitamin C per 100 grams as does an orange, up in the super fruit range. No one eats them raw, of course, because they are extremely bitter and probably would stain your mouth black.

In Europe, many countries have traditional recipes for preserved fresh or green walnuts, in their case it is Juglans regia, the Carpathian Walnut. The recipes have been duplicated in the US, using Black Walnut fruit, by a handful of individuals who have blogged about it. The two general options seem to be picking or preserving in sugar. I've just tested samples of a half a dozen such products purchased online from Romania, Italy, England, and Greece. They are all richly delicious, but only the pickled ones retain any Vitamin C content, around the same as a fresh orange that I used as a comparison fruit.

I wonder how fruits of the Black Walnut could be processed for food in a way that retains their full Vitamin C content? I also wonder if a food product could be created that wasn't as rich and intense as those preserved with vinegar and sugar? Like I said, they are delicious, but they are small-serving, side dishes.

Since we have many Black Walnut trees, I plan to be experimenting for a month or more this summer. Anyone have ideas? Have you tried processing and eating fresh green Black Walnut fruit?

This is a fascinating question. I would have assumed that "green" black walnut fruit was utterly inedible. But then again, an unprocessed olive isn't exactly palatable-seeming either.

The recipes have been duplicated in the US, using Black Walnut fruit, by a handful of individuals who have blogged about it.

Do you have any links? I would love to see those!

I don't actually have any black walnuts on my property (except for some tiny seedlings) but there are lots of unloved trees in public spaces near me that I can harvest from.