RE: Food irradiation

[Franz Schoenhofer <schoenho@via.at>]

At 04:33 04.04.2000 -0500, you wrote:
>
>
>
>	Yes I'd like to.  Does anyone out there know about the analytical
>tests that detect if food is irradiated?  I know I read about this a few
>years ago, but of course I've now forgotten the details.  I'm sure it
>involved measuring some long-lived free radicals.  The fact that food can be
>detected as irradiated means it's qualitatively different to food preserved
>by some other means.

Well, food in which you can detect traces of heavy metals (they are
everywhere anyway) or a little Cs-137 is not qualitatively different from
some other food, unless other criteria like contamination with
microorganisms, unacceptable concentrations of toxins, etc. come into the
play.

Regarding your question:

There are many methods to detect the irradiation of food, much depending on
which kind of food. Contrary to the opinion of another RADSAFEr free
radicals can persist for a relatively long time as long as they are trapped
in a dry matrix like bone of poultry, shells of shellfish, dried spices.
Free radicals can be easily detected by electron spin resonance for
instance in bone or in small sand particles isolated from spices. Also
thermoluminescence is a well known method to detect irradiation of various
solid materials, including spices. 

Chemoluminescence forms when for instance spices are mixed with a
luminescence agent and can be detected. The signals are proportional to the
irradiation dose, so even the dose can be controlled. 

If you have meat like beef or boneless chicken pieces, then irradiation
gives rise to the formation of traces of characteristic hydrocarbons
(alkenes) by radiolysis (action of free radicals on fatty acids) which can
be detected and quantified by gaschromatography. 

Certain enzymes are destroyed by irradiation. Therefore characteristic
enzyme reactions like color formation or destruction with special reagents
will fail.

Potatoes, onions, seeds etc. will not sprout (which is of course wanted).

Viscosity of solutions may change. etc.etc.

Hope this first "collection" of methods helps.

Do not forget that you can also test, whether meat has been grilled, boiled
etc. by tasting it. To detect the food treatment does not automatically
mean, that the food has been altered to something less nutritional or less
valuable.


Franz


Franz Schoenhofer
Habicherg. 31/7
A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at


Office:
Hofrat Dr. Franz Schoenhofer
Federal Ministry of Agriculture, Forestry, Environment and Water Resources
Radiation Protection Department
Radetzkystr. 2
A-1031 Vienna
AUSTRIA

phone: -43-1-71172-4458
fax: -43-1-7122331

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