Radiation sterilization of prototype military foods. 3. Pork loin.

Ten lots of pork loin, packed in cans, were inoculated with approximately 10(6)Clostridium botulinum spores per can. Each lot was seeded with a different strain; five type A and five type B strains were used. The pack comprised 5,690 cans, including controls, and contained about 10(9) spores per dose. The cans were irradiated with Co(60) in the range of 0 to 5.0 Mrad (0.5 Mrad increments) at 5 to 25 C, incubated for 6 months at 30 C, and examined for swelling, toxicity, and recoverable C. botulinum. The minimal experimental sterilizing dose (ESD) based on nonswollen, nontoxic, but nonsterile end points was 2.5 < ESD </= 3.0 Mrad, and based on non-spoiled sterile cans was 3.5 < ESD </= 4.0 Mrad. The theoretical minimal radiation dose (MRD), the 12D equivalent, varied with the method of computation: 4.74, 4.33 +/- 0.17, and 4.19 to 4.99 Mrad were obtained by the Weibull, Spearman-Karber, and Schmidt-Nank techniques, respectively. Calculation of D and MRD values by the conventional Schmidt-Nank method produced increasing values with rising dosage; this finding was compared with the data derived by the other two methods of calculation. Suggestions for estimating the MRD of a prototype radiation process are offered.