Back in the 70's, the folks at Mother Earth News performed an egg storage experiment. They stored them in a variety of ways, both refrigerated and unrefrigerated, to see how long they could keep. They concluded that unwashed eggs (aka, "hen fruit" or "cackleberries") stored in a sealed container, and kept at 35° to 40°F, were still perfectly edible after seven months:
(1) Unwashed, fertile homestead eggs seem
to store much better than washed,
unfertile agribiz eggs. Why? Probably
for the simple reason that they're
unwashed ... and not because they're
fertile. Hen fruit, as it comes from
the chicken, is coated with a light
layer of a natural sealing agent
called "bloom". And, while a good wash
may make a batch of eggs look more
attractive, it also removes this
natural protective coating ... leaving
the eggs more subject to aging and
attack by the air and bacteria in the
air.
(2) The very best way we've found to stash
eggs away for long-term storage is in
a sealed container at a temperature of
35° to 40°F. Their whites may become
somewhat runny looking over a period
of time, but even after seven
months—the cackleberries stored in
this manner smell good, taste good,
have a good texture, and—in short—seem
"almost fresh".
Update 2011-02-19: This discussion inspired me to do some experimentation of my own. We keep chickens, so I plucked two eggs on October 2, 2010 and put them in the refrigerator. I just pulled them out today. Here's a picture of one of them next to a fresh egg.
One of these eggs was laid yesterday and the other was laid 140 days (4 months 17 days) ago. Can you guess which is which?
Update 2011-06-05: I completed my eggsperiment today by cracking open two more eggs that I have had in the refrigerator since October 21, 2010. Here they are:
There was no trace of odor, but the whites were definitely lacking in firmness. I scrambled them. They didn't make for very fluffy scramblers due to the watery whites, but they tasted fine. So, I can confirm the findings of the Mother Earth News experiment. Fresh, unwashed eggs stored in the refrigerator were perfectly edible after 7 months 15 days (227 days)!
Best Answer
While, in general, vinegar retards the growth of certain bacteria (botulism), some allow the growth of others that are harmful. You should sterilize the glass containers by first washing them in hot water and soap, and then boiling for about 10 minutes and scalding the caps in boiling water. Filled and tightly sealed, your shrub should last about 6 months in the refrigerator. Opened and used occasionally, they should last 6-8 weeks, not unlike similar condiments that are kept refrigerated. Keep in mind that, should you include fruit in your original batch, it will age and, eventually, become a fruit vinegar.