Before doing this, you might want to check out the food preservation
newsgroup (sorry, can't think of the exact name). The question of using
herbs and fruits to flavor olive oil and vinegar has been discussed many
times. Since vinegar is nothing more than overly fermented alcohol, they
can probably give you some tips or point you to some good sources of
information. There are some risks to flavoring liquids with fresh
Actually, vinegar is a competing bacterial by-product totally different
from alcohol. When you're making wine, you introduce a yeast in hopes
that it wins the microorganism wars, successfully colonizes the
solution, and starts converting sugars into alcohol. However, there's
plenty of wild acetobacter in the air, and it's always a risk that the
acetobacter will win and turn your grape juice into acetic acid (vinegar).
You can even turn wine into vinegar, since few wines are fermented to
completion (where there's no sugar left). There's almost always
something for the bacteria to eat. And heck, for all I know,
acetobacter might even be able to eat low concentrations of alcohol (my
expertise is alcohol rather than vinegars, so I'm really just making
that last part up).
Alcohol in high concentrations (anything above 20%) is a great
disinfectant, though, and will kill yeasts and other bacteria instantly.
This is why strong liquor doesn't spoil, it just goes stale. It
doesn't get colonized by deadly organisms, it just dies from oxygen
So alcohol is a fine preservative as far as it goes. When you put
things in alcohol, though, there's always the danger of those areas that
don't come in contact with the alcohol to spoil on their own. Egg-based
liqueurs, at least those made at home, have a shelf life measured in
weeks because the eggs never completely mix in. There are always
strands of albumen that can spoil despite the vodka only a millimeter away.
Making liqueurs from fruits is an old and well-tested hobby, so I doubt
there are any significant hazards involved with it. Certainly, in the
years I've done it, the worst things that have happened to me have been
liqueurs that just don't taste good, and the occasional one that turns
to jelly. Gotta love high-pectin fruits.
Oh, and the danger of the fruits themselves oxidizing in the liqueur,
which is why you want to pull them out as soon as your flavor
concentration is high enough. A touch of brown on a peach liqueur can
add character, but too much brown will kill any liqueur.
Anyway, my site on making liqueurs, such as it is, is he