Decoration food long-term preservation

None of the classic food preservation techniques will work for you. They are about having the food stay edible, not stay beautiful.

Most fixation solutions will work, but you probably don't want to keep them around your house. For example, if you filled the bottle with formaldehyde, it will not only be a major problem should it break in an accident, but I'd be also worried about anything which might seep through an imperfect seal - it is highly volatile, and neurotoxic and carcinogenic already in the ppm levels.

The one good way I see to do it is to use man's favorite poison: alcohol. Fill the bottles with ethanol until they are fully submerged. In principle, drinking alcohol at 37.5% will do, but in this case, the stronger, the better. Just use medicinal ethanol, it's also cheaper because you don't pay taxes.

First suggestion

Fill the bottles with clear resin.

I used this many, many years ago at a church camp where we made our own keyrings by surrounding a small object with clear resin. I remember it as being reasonably straightforward. Google returns lots of how-to videos for using it.

I don't imagine it will keep the food for a long period, as biological processes will still take place in the entombed items, but it might be long enough for your purposes.

Second suggestion

Scan the food items, 3D print them in a material that won't decompose, paint it, put it in the bottles surrounded by plain water. :-)

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Vacuum canning is probably the most practical approach. The jars in the photo below are a half gallon in size. And, of course, the sizes just go down from there.

This pretty much limits you to the use of Ball mason jars though. But you could carry some of their lids around for awhile (just the disks) and see if somewhere you can come upon some alternative jars whose mouths just happen to be the same size as that of the Ball's. That' what I would do. Don't worry about not having the screw-on part. Just prep the rim with an ultrathin coat of soft glue, (just so nothing can snag itself under that slight, exposed little lip), and let your decorative genius take care of the rest!

There are a variety of vacuum sealing machines on the market. The one pictured below is a Wolfgang Puck. For any of these machines the same principle is employed. The disk for the jar fits into a cap. The cap is placed onto the jar. Air is drawn from the jar by attaching a hose to a port in the top of the cap. Voila!

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