I’ve been frustrated trying to ripen the American persimmon Prok here. If I pick the fruit mostly ripe off the tree, it retains some astringency. If I wait until the fruit drops, it may still be slightly astringent but it also has begun to spoil. I don’t know whether that’s fruit flies or some ground organisms (e.g., bacteria, yeast). Also, the texture of the fruit harvested from the ground is unappealing – very sloppy.
I’ve started experimenting with alcohol. The results that I report here are very preliminary but I’m impatient, so here’s what I’ve got so far. The method is simply to place the fruits in a closed container with a small glass of vodka. The vodka evaporates. The alcohol vapor penetrates the skin of the persimmon fruit. The ethanol is transformed to ethanal (acetaldehyde). The acetaldehyde binds tannins. Otherwise ripening proceeds because that’s what happens once the process starts. My tentative conclusions:
There’s no point in taking “fully” ripe but maybe still slightly astringent fruits off the ground and subjecting them to alcohol. Spoilage organisms will continue to do their worst.
There is a point in taking almost fully ripe fruits from the tree. These fruits generally have not yet started to spoil and, based on observation of one batch of 12 fruits, it seems to me that spoilage doesn’t start in almost ripe whole fruits in a closed container surrounded by alcohol vapor. Moreover, these almost ripe fruits appear to fully ripen within 2-4 days. At that point there is little or no astringency. Also the fruit is still reasonably firm.
It’s too early for any firm conclusions. More to follow . . . .
Anything with a high enough concentration of ethanol should work. However, rubbing alcohol is generally not guaranteed to be food safe, so proceed with caution. Vodka or everclear would be safe bets.
My experience closely mirrors yours. I have a large american persimmon tree behind my house. I don’t know whether it’s a named variety since it was here when I bought the place. I picked approximately 20 persimmons both off of the tree and off of the ground. I put a couple tablespoons of Vodka in the bottom of an ice cream bucket. Then I put a collapsible steamer basket inside. I put the persimmons in the basket so they would be held off of the bottom.
Within 24 hours the softer ones had already lost all astringency. In 72 hours even the harder ones had lost all astringency, but the the softer ones that I had left in the container were spoiled.
I picked a larger batch yesterday. This time I made sure that they were all more firm. I also pick a few that weren’t colored up completely to see how they will be.
I didn’t even realize this was a new topic! I’m glad to see you tried it, and thanks for reporting your findings. That’s very exciting that it works. It looks like eating American persimmons in the firm stage is within reach!
Haha. Well, “firm” may be an overstatement, especially when compared to non-astringent Asians. On a scale of 1-10, where 1 is jelly and 10 is a green tomato, an edible but firm Asian may be roughly 7-8; a ripe American picked off the ground is ~2, these fruits are 4-5.
Also, this assessment is extremely subjective. Others may have different views.
How early did you pick them? I think if you pick them as soon as they color up, it might stay firmer (but maybe not as sweet). Also, I’ve been thinking about whether including an ethylene absorber might slow down the softening process.
Personally, I really like the jelly texture, but I also like variety.
I doubt the chemistry works. Ethanol is produced naturally inside the fruit. A simple enzyme-driven reaction reduces the ethanol to ethanal / acetaldehyde, which is what binds the tannins as a normal part of ripening. I doubt that any other alcohol would achieve the same result.
Any 80-proof (40%) alcohol would work. Probably tasteless is better. So vodka, rum, grain alcohol.
I picked a dozen, ranging from mostly orange (some green remaining) to entirely orange. A few needed to be pulled off the tree, most came loose with a slight tug. Unfortunately, I then treated them all the same so I can’t report on the impact of these slight differences.
I’ve been mulling the same issues as you – would earlier picking be better (less spoilage) or worse (less sweetness, more astringency)? At this point, I have no idea.
I think that there are two processes that we’re trying to manage and optimize. One is the reduction of astringency. Here, alcohol appears to work. The other is development of sweetness / flavor, which is a process that I don’t understand as well. I assume it’s mainly starches turning to sugars, which I’ve learned to track in apples. I was wondering if more ethylene (e.g., a nearby apple or banana) might help. I’ll have to do some reading.
Rubbing alcohol comes as either ethanol or Isopropyl alcholol. I definitely wouldn’t use Isopropyl (safety and it probably wouldn’t work), and I’d be slightly concerned about food safety of an ethanol-based rubbing alcohol.
FYI, ethanol is sometimes sold as “denatured alcohol”. My understanding is that denatured alcohol is usually ethanol with additives that make it unfit for drinking. One source says, “The term ‘denatured alcohol’ refers to alcohol products adulterated with toxic and/or bad tasting additives (e.g., methanol, benzene, pyridine, castor oil, gasoline, isopropyl alcohol, and acetone), making it unsuitable for human consumption.” I wouldn’t use denatured ethanol – or any other product not fit to drink.
My thoughts exactly. Denatured alcohol is meant as a solvent or fuel. I have a camp stove that runs on ethanol. I like to use Everclear because it’s food safe in case there’s a spill, but I might have to switch back to denatured, since the state liquor stores don’t carry full-strength everclear.
I had a few American Persimmon that def looked hard/unripe in large spots that got knocked off the tree (by a squirrel maybe). I just put them outside on the window sill, and the sun or cool night temperatures would ripen. But I always read you can’t do this with American Persimmon so I’m curious if others have tried it.
My Prok persimmons seem to be ripening OK (and losing astringency) in a closed container with alcohol. Honestly though, I’m enough of a scientist to know that I don’t have a control group. I need That should be my next step.
Specifically, I’m imagining 4 sub-batches: (1) alcohol (i.e., a small cup of vodka), (2) ethylene (e.g., an apple or banana), (3) both, and (4) neither.
Meanwhile I should note that my related effort to produce an edible puree has been an abject failure. Mashed, mostly ripe, but still somewhat astringent Prok (not Asian) persimmons can produce a nearly palatable starting mash. But then adding alcohol directly to the puree does not eliminate astringency, even after 2 days. Adding gelatin similarly has a modest apparent benefit, if any. Heating the mix doesn’t help. The result is consistently disgusting. The texture is mealy. The taste is still astringent and if anything it is less sweet that the starter mash.
when I do this outdoor method btw, they are orange but hard in some parts (not in a very unripe green state). Anyhoo interested in @jrd51 and having a control group to test against… maybe try 2 controls, an indoor (without alcohol) vs outdoor control (cold nights + sun).
I’d be curious if this is similar to pawpaws, where if they are close enough to ripe when they are knocked off, they have a chance to ripen, but if too early they never ripen.
@disc4tw – Yes, it is. Reportedly, once the ripening process has started in a persimmon, it can continue off the tree. Non-astringent Asian persimmons are routinely ripened indoors.
The additional challenge here is removing the astringency in an American variety. It is known that whole astringent Asian persimmon, such as Hachiya, will not only ripen but also become non-astringent if enclosed in a container that promotes anaerobic (low oxygen) metabolism. CO2 works. Alcohol vapor also works. I’m trying to apply the alcohol technique to astringent Americans.