Effect of irradiation temperature in the range −196 to 95C on the resistance of spores of Clostridium botulinum 33A in cooked beef

Abstract

Cans of ground cooked beef, inoculated with 106 or 108 spores per can of Clostridium botulinum 33A, were irradiated with 60Co gamma rays at a series of 14 temperatures ranging from −196 to 95C. The higher inoculum level required higher sterilizing doses. The D values, computed on the basis of recoverable C. botulinum, were independent of the inoculum level, and showed that spore resistance progressively decreased with increasing temperature. A statistical analysis of these data disclosed that the change in D values from −196 to 65C followed equally well a quadratic, exponential, or linear best-fit plot; above 65C radiation death was much more rapid. An equation was derived from the linear plot to predict D values for any desired temperature between −196 and 65C. Calculations of Ea and Q10 values, based on the linear curve, indicated a very small thermodynamic effect on radiation kill. An Arrhenius analysis of the temperature effect suggested that there was no simple physicochemical mechanism occurring in the inoculated beef pack which might explain the change in spore kill as a function of temperature. Theoretical commercial radiation processes for beef, based on the 12D concept and strain 33A spores, are presented for several easily controlled irradiation temperatures.

A novel radiation-resistant Deinobacter sp. isolated from irradiated pork

“…The range of sensitivity of bacteria commonly found in foods is large, for example, the D,, value of a Pseudomonas juorescens strain irradiated in a low fat beef at 5°C was 0.13kGy compared to 0.58 kGy for Staphylococcus aureus irradiated under the same conditions (Maxcy & Tiwari 1973). Clostridium botulinum type A spores were found to have D,, values ranging from 3.4 to 3.6 kGy in cooked beef irradiated at 25°C (Grecz et al 1971).…”

Research Note: Irradiation Dose and Temperature Effects on the Sensory Properties of Turkey Frankfurters

“…Reducing the product temperature below freezing for irradiation was reported to reduce lipid oxidation (Brynjolfsson, 1979). However, freezing the product for irradiation provided better protection against bacteria spores (Grecz et al, 1971) which means that a higher irradiation dose will be needed to achieve the same degree of microorganism inactivation. The effect of irradiation on C. botulinum survival in reduced-salt products was reported by Barbut et al (1987); neither .5 Mrad nor 1.0 Mrad inhibited toxin production in reduced-salt frankfurters containing 1.5% NaCl.…”

Development of Irradiated Beef. 1. Acceptance of Beef Loin Irradiated at Cryogenic Temperatures

“…10°C irradiation temperature and 5.7 megarads at -80~C irradiation temperature (Wierbicki et al, 1970). This is because theresistance of C. botulinum spores to radiation increases when product temo 0 perature during irradiation is lowered from +65 to -196 C (Grecz et al, 1971). However, for the development of irradiated beef products prior to determining these sterilizing doses, a dose range of 4.5 to 5.6 megarads -3-was used for all temperatures of irradiation.…”