Radiation Sterilization of Prototype Military Foods

Abstract

Ten lots of diced cured ham, packed in cans, were inoculated with approximately 106 Clostridium botulinum spores per can. Each lot was seeded with a different strain (five type A and five type B strains). All cans were irradiated to various dose levels with Co60. Evidence provided by swelling, toxicity, and recoverable C. botulinum with 6,350 cans demonstrated that: (i) 4.5 Mrad was more than adequate as a sterilization dose; (ii) the minimal experimental sterilizing dose (ESD) based on nonswollen nontoxic endpoints was 2.0 < ESD < 2.5 Mrad, and based on nonspoiled sterile cans was 3.0 < ESD < 3.5 Mrad (the latter was supported by the computed theoretical 12D dose); (iii) D values calculated from botulinal survival data indicated that, as a group, the type A strains were more radioresistant than type B strains; strains 12885A and 41B, with respective D values of 0.242 and 0.175, represented the most resistant of each type; (iv) swollen cans did not always contain toxin, nor were toxic cans always swollen; (v) viable C. botulinum can exist for 6 months at 30 C without producing visible or toxic spoilage at doses of 3.0 Mrad and lower, including, in some instances, 0.0 Mrad; and (vi) a phenomenon similar to heat activation of spores occurred at sublethal radiation doses. MATERIALS AND MErHODS Test organisms. Ten strains of C. botulinum were used: 33A, 36A, 62A, 77A, 12885A, 9B, 40B, 41B, 51B, 53B. These strains represent the highest, lowest, and intermediate radioresistances of 102 strains screened in a model system (4). The sources of these organisms, their serotypes, maintenance, and spore preparations were previously described (4). The only modifications employed were the substitution of distilled water for buffer as the spore diluent, and the use of pork-pea-agar (2) in conjunction with screw-cap 166

An Experimental Design for Determination of D‐values Describing Inactivation Kinetics of Bacterial Spores; Design Parameters Selected Using Computer Simulation

“…For purposes of illustration let us suppose that the dilution factor is 10. Each can in the first row of the array (corresponding to zero dilutions, SD=O) receives a spore load equal to the stock LAMBDA on average Anellis et al (1967) per aliquot. Each replicate in the second row (SD = 1) receives l/lOth LAMBDA on average per aliquot.…”

“…Quantal-response experiments are those in which the remaining number of replicates containing viable microorganisms are counted from among the N inoculated replicates that are subjected to a lethal environment. This type of experimental design has been used for example, in determining the death kinetics of C. botulinum spores (e.g., Anellis et. al., 1967, andHachigian, 1979).…”

“…Further, compounding these concerns, it is commonly understood (Olkin et al, 1980) that the difference between two competing models describing death kinetics is best observed at the extremes of the range over which the experi- 1989 ment is conducted-precisely where the incorrect results are most likely to occur. Data from Anellis et al (1967) (Table 1.) on radiation sterilization using Cofio illustrates these points and the need for more carefully designed dose spacings, spore loads, and replicate numbers so as to obtain sufficient data with which to conduct statistical analyses.…”

Low-Temperature Irradiation of Beef and Methods for Evaluation of a Radappertization Process

“…Some food products can withstand the effects of sterilizing doses of ionizing energy better than other foods. Prototype radappertization (24) processes for several of the less sensitive items such as bacon, ham, pork sausage, corned beef, pork, and codfish cake have already been reported (3,4,6,7).…”

Effect of low-dose (1 kGy) gamma radiation and selected phosphates on the microflora of vacuum-packaged ground pork

“…The use of low-dose gamma radiation to extend the shelf life of fresh meats has been proposed by several investigators (Anellis et al, 1967;SivinsJcy, 1983) Huffman, 1974;Silliker et al, 1977;Sutherland et al. 1977;Enfers et al, 1979).…”