Plum preserving/storage method that tastes like plums, not prunes (I just picked 30 lbs)

Question

I just did some neighborhood foraging and picked 30 pounds of red plums. They are delicious, but even I will have trouble eating them all this week.

Last year we made jam/preserves but it ended up tasting very prune-like, i.e. not the tasty fresh plum flavor. We tried varying amounts of heat and sugar and the prune flavor prevailed. We're open to canning, freezing, drying, making jam, etc. but want to do the best job to capture that tasty plum flavor. I've read some other answers on what to do with tart plums and peaches, but our plum challenge is a little different.

Question: what is the best method to preserve the fresh plum-like flavor?

Answer 1

The "fresh fruit" aromatic compound in plums is likely ethyl propionate, which has a boiling point at sea level of just under 100°C. The prominent flavor compound for prunes, according to this study, is 3-methylnonane-2,4-dione, which has a much higher boiling point of about 235°C (likely much higher than the temperatures you would reach during jam/preserve making). Therefore, to preserve the fresh fruit taste, I would recommend not heating the plums higher than 100°C. This presents a couple issues, however:

1. such low temperatures are not sufficient to preserve the plums through Pasteurization; and
2. traditional jams/preserves are set using the naturally occurring pectins in the fruit, however, pectin does not gel until around 104°C.

Here are some ideas (although I have never tested them):

• If you have access to a vacuum sealer, you can lower the required temperature for pectin to set by reducing the pressure of the mixture. Blend the ingredients for the jam in a blender and then vacuum seal. Boil the sealed bag at ~80°C, which should hopefully be high enough for the pectin to set, but low enough for the desired flavor compounds to stick around.
• Use an alternative gelling agent that sets at a lower temperature, such as agar.

Note that neither of these methods will produce a product with a long shelf life, since it was not heated to a sufficient temperature to kill off bacteria. Therefore, they should be refrigerated and eaten relatively quickly. You could also experiment with boiling the product for a short period (seconds) at the very end.

Answer 2

This won't be a very scientific answer, but I likewise experience an over abundance of plums every year and I am likewise not a fan of prunes.

I've had a lot of luck though turning my plums into plum sauce, rather than actual jam (not the kind you put on spring rolls). I use less sugar, no added pectin, and only cook until the plums breakdown into a mushy consistency, then can in a water bath. Absolutely delicious on ice cream, yogurt, cake, or pretty much anything.

My other solution is to use some for plum chutney, but that seems to last a whole lot longer in my pantry.

Answer 3

I think freezing would be your best bet - not fantastic for the texture, but when defrosted you could make a pie/cobbler or other cooked item with them. Plenty of web sites (eg http://www.fruitexpert.co.uk/using-up-a-plum-glut.html) say you can just halve them and freeze them on open tray, then when they're frozen move them into plastic bags. It's the lowest-effort option so probably worth trying on at least a fraction of your harvest.

Answer 4

Have you tried adding a strong acid medium like whey, kefir or wine/vinegar that might speed up the pickling process? Also, I'm not sure what cooking them will do to the flavor.

I have heard that adding oak leaves to pickles will keep them crisp...maybe there's something like this for plums to keep them tart.

Does store bought plum jam taste like prunes as well?

Sorry for not providing any solid answers...I hope my thoughts have sparked a light bulb.