[Sca-cooks] oil & vinegar dressings

[kingstaste at mindspring.com]

Thanks to everyone who answered my oil and vinegar dressing question.  I
shall continue to keep my salad dressings in the frige.

What does racid oil smell & taste like?  I always keep my oils on the bottom
pantry shelf.  Of course, this shelf is on a common and a north facing wall,
right behind my back door.  Maybe that has had something to do with keeping
me from bochilizing  (sp? hahaha) myself all these 23 years.
Phillipa


Rancidity in oil is caused when one of the open molecule spaces (the more
open spaces on the molecule chain, the more fluidity to the oil, solid,
saturated oils are all filled in, monounsaturates like olive have only a few
openings, polyunsaturates have lots more) anyway, when one of these open
spaces gets filled in by a random oxygen molecule, you get oxidation, which
causes the rancidity.  Rancid oil has a sharp, almost sour smell to it,
maybe with some nuttiness mixed in.  It smells very different from the oil
when it is fresh.  You should never use rancid oil.  The resulting oxidized
molecules are carcinogenic, a bad thing to ingest.  Same for oils that have
been heated past their smoking point.  Polyunsaturates like sunflower,
safflower, and the other really light-colored oils go rancid the fastest.
Keeping them cool slows down the oxidation process.  Olive oil should be
stored cool, but if you have to keep it in the fridge, there is nothing
permanent about the partial solidification you get, just sit it on the
counter for a couple of minutes or run it under some warm water.  I wouldn't
microwave it, you will heat it up,loosing some of the health benefits, and
if you believe the theories about microwaved foods, you could be changing
the molecular structure of it to who-knows-what.  You should also buy your
oils in glass containers, not plastic, plastic and oil being too close
molecularly and having the possibility of dissolving plastic molecules into
the oil.

I don't know why, but I find oil chemistry fascinating.  Alton Brown uses a
train and some monster puppets to explain the 'open space on the chain'
thing, which is very cute and really understandable.  I've taught classes on
nutrition where we teach about some fats being better than others, and I've
taken training from oil manufacturers that go deeper into the chemical
structure, along with lots of other reading.  Usually food chemistry is ok,
but I don't care too much as long as I understand how to make it do what I
want it to do.  There are just so many 'do's and don'ts' out there about
which fats to use and how, and the more you study the structure, the more
they all make sense.
Ok, back to your vinaigrette - keep it cool, use it quickly, make smaller,
fresher batches.
Christianna