@BobVance@Harbin I’m not entirely convinced about the astringency returning thing, as there’s a long tradition of turning fully ripened D. virginiana fruit pulp into baked goods. However, there isn’t really a big tradition of making jams and the like. There may be some magic happening in the presence of flour that keeps the tannins in check, that just doesn’t happen when you’re doing something like a jam.
If a fruit is still astringent, all bets are off. I’ve made a few batches of autumn olive jam that were inedible because the astringency got so concentrated. The raw fruits weren’t bad, but the jam was just too much!
I’m still waiting on my trees to fruit so I can start testing, but in short I’ve heard of success with some hybrids but not others (I don’t remember which off the top of my head), and no successes with D. virginiana. I’m convinced that it’s possible, as it’s likely the astringency differs in quantity not in type, so should respond to the same types of treatments. My understanding is that even among kaki, there is varying responsiveness to treatment.
The approach that I find most promising is submerging in a hot water bath (60c) for an hour. I’ll have to dig up the paper again, but the researchers found that kaki fruit responded really well to this treatment, but if left too long, the astringency would come back. The fact that the astringency comes back makes me think one of two things is going on with hybrids and virginiana:
The astringency is lower in hybrids and virginiana, so we may be overdoing it
The astringency is so high in virginiana that it doesn’t fully dissipate before the “coming back” mechanism kicks in
2a. Astringency is so high that maybe they need more time in ethanol or CO2, or it just takes so long that the fruit has naturally softened anyway by the time it’s done.
Again, this is all speculation. I know @jrd51 has chipped away at some aspects of this, and I’ve seen no successes with virginiana yet*. However, I do believe there are a few variations that haven’t been tried yet. I’d like to explore these more thoroughly before ruling out the possibility. It may be as simple as certain varieties of virginiana work and some don’t.
*I did see one video where a guy was putting some virginiana in a container with some vodka to remove astringency. The fruit were ripe enough to shake from the tree, so I’m not convinced the ethanol actually did anything… I’ll add a link to the video if I can find it again.
Here’s the video. I was wrong, he is picking the fruit hard. However, he doesn’t address whether the fruit is still hard after the ethanol treatment, nor does he compare to fruit that have just been left out at the same time. So, it’s an intriguing anecdote, but not airtight by any means.
During the heating process the cells break and release soluble tannins that cause astringency. You can try it by yourself to see if true or false. I guess that gentle and short simmer might work…haven’t tried that to be frank. There might be some interaction with flour that stops tannins to be soluble. So cakes are probably manageable.
@Harbin – I’ve read that some proteins (e.g., gelatin) can bind tannins and make them insoluble. Last year I tried adding gelatin to a paste made from my Prok fruit and the result was a thick mess that resembled wet concrete – and it was still astringent.
But I’m still optimistic that some other protein(s) would work.
I tried vodka on my Prok. I put whole fruit in a closed container with a cup of vodka. I also mixed vodka directly into paste. No discernible impact.
There seems to be a very consistent finding that processes that work with PCA kaki (e.g., CO2, ethanol) do not work for DV. I wonder if the difference is not merely quantitative but qualitative, meaning that something about the manufacture, storage, and or neutralization of tannins in DV is different.
I believe you, but I feel like it would be a chemical process rather than a physical one. Cells rupture when you freeze the pulp or when you chew on the fruit, and honestly the cell walls are mostly broken down by the time the fruit is softened. A more likely pathway, in my estimation, is that high enough temperatures would re-solubilize the tannins that had previously been converted.
Interesting note: I looked at a couple of recipes for persimmon pudding, and both call for baking soda without any acid ingredients. One of them specifically says to stir the baking soda into the pulp. So, a higher pH might be the key to mediating whatever happens when the pulp is cooked. Unfortunately, that doesn’t work for jams, as they rely on lowering the pH. They do stick to the older belief that there needs to be a frost before you pick them, though, so take this with a grain of salt.
Most kaki persimmons taste fairly similar to me – kind of honey sweet with slight variations of high notes that I’d call brown sugar or caramel. American persimmons have much more depth of flavor – flavors like apricot, molasses, and something like toasted nuts. Hybrids are the best of both world, they’ve got depth of flavor but a lot of honeyed sweetness too. The first few JT-02 I’ve gotten this season have been excellent. Probably better than Kasandra, but I’ll need to compare them side-by-side when Kasandra is ripe next week. I’d picked that first Giombo too soon, so I’ll have to report back on the next round when they’re ready.
Maybe try acetaldehyde? From what I’ve read, higher temps “lock in” the tannins, but in the paper referenced below they were able to remove astringency from persimmons treated at 80C only by adding acetaldehyde.