"nick" <[email hidden]> wrote in message
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Quoted message said:Is there a DIY test to see if the olive oil I was given in a bottle whilst on holiday is really
olive oil? A test I can do in my kitchen using
typical
Quoted message said:kitchen equipment. The oil might be diluted with some other oil, which is not unusal, and no
attempt would have been made by the adulteres to make testing difficult enough to require a lab.
Try crossposting to one or two of the chemistry related forums. I'd bet Uncle Al might just rise to
the challenge. I'll suggest that since adulterate oils would contain more polyunsaturated, the
temperature at which the oil turns into a soft solid would be lower in the adulterated oil. I'd
suspect "mild" adulteration would be done with rapeseed oil as it contains a fair large percentage
of monounstaturated fatty acids. Still it contains more polyunsatururated fatty acids than olive oil
if I recall correctly. You would have to work your own standards based on good olive oil, a sample
of rapeseed oil, a sample sunflower seed oil, and soy oil. Of course the adulerator may have also
used a bleached palm oil, in addition to rapeseed oil with result the solid point might be quite
similiar to the real thing.
Costco sells a pretty good dark virgin olive oil. It isn't cheap, I think is about 10 dollars a
liter. It is in a dark bottle which help slow the oil from degrading. Olive oil in clear bottles is
a bad idea as even a day under fluorescent lights will result in taste changes.
A color change induced by some chemical change at unsaturated bond might work though a device to
quantify the color change might be needed.
OK I recall now it is an "unsaturation test", (I refreshed myself with a book) I did this one "back
in the day". You need test tubes, some potassium permanganate, an accurate scales $$, methylene
chloride, bromine solution (damned nasty stuff that HBr solution). Any intro to organic lab
techniques textbook would complete the discussion of how to. You need a decent lab if simple lab for
this one. Plus you need the antidote for HBr contact..........as I recall
Heres another test the Baeyer test, you may need some solvents possible "just" ethanol or isopropyl
alcohol, a 1% solution of potassium permanganate. Problem is that it will detect all double bonds
and hence your oils will make a lot of brown ppt. It would take a fair bit of fussing and accurate
screwing around to get a technique that would yeild some hints. You need to measure the weight of
brown ppt from each standard oil and your assay oil.
No longer "back in the day"............ ...........................William A. Noyes
