Re: Sterilisation Dose

[don@radpro.uchicago.edu]

According to articles on food irradiation in _Food Technology_, May 1994, 
pp. 124-144 (pub. by the Institute of Food Technologies, 221 N. LaSalle St.,
Chicago, Il 60601):

"The D value of Vibrio vulnificus, V. cholerae, and V. parahaemolyticus is 
in the range of 0.1 - 0.2 kGy, depending on the media.  Thus a dose as low
as low as 1 Gy [will] reduce the population of Vibrio spp. by 5 - 10 orders
of magnitude ...."  [supra, at 128.]  I don't know what a "D" value is, though
one could reconstruct a definition from the data above.

The D value for Listeria monocytogenes is give as 0.27 - 1.0 kGy, depending 
on the strain. [supra, at 128.]  This bacterium seems to be prevalent in
processed foods.  

"E-coli O157:H7 is also highly sensitive to radiation.  Its D values appear to
be of the same order as those of Salmonella, i.e., 0.16 - 0.44 kGy in ground
beef and mechanically deboned chicken meat (Thayer and Boyd, 1993).  These
authors concluded that E-coli could be easily controlled in meat products
by irradiation at 1.5 - 3.0 kGy. "  

The "sterilization" dose appears to depend on how sterile you want the 
material to be, as well as the species & the medium.   I hope this helps
answer your inquiry.  

___________________________________
Thayer, D.W. and Boyd, G. 1993.  Elimination of Escheria Coli O157:H7
in meats by gamma irradiation",  _Appl. Environ. Microbiol. 59: 1030-1034.

Other potentially useful references give in this article:

IAEA.  1993.  "Use of Irradiation to control infectivity of food-borne
parasites."  STI/PUB/1993, IAEA, Vienna, Austria.

Josephson, E.S. and Peterson, M.S. 1983.  "Preservation of Food by Ionizing
Radiation", CRC Press, BOca Raton, Fla.
_____________________________________

Now, back to lunch.
___________________________________________________________________

Don Jordan                          Tel. (312) 702-6299
Office of Radiation Safety          Fax        702-4008
The University of Chicago           email: don@radpro.uchicago.edu
1101 East 57th Street, Room 11
Chicago, Illinois  60637  
                -- Any opinions are the author's --