Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy

Abstract

The thermal resistance of spore crops produced from each of two ileal loopreactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two-to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators.

Challenging the assumptions around the pasteurisation requirements of beer spoilage bacteria

“…Briefly, 50 μL of solution containing between 10 7 and 10 8 CFU/mL was introduced into the soda glass capillary tubes G119/0,2 (Fisher Scientific, UK); the tube ends were heat sealed and processed within 15 min. As shown by Bradshaw et al (23), sealing the capillary tubes did not affect the testing solution. The sealed capillary tubes were then submerged in a water bath at the test temperatures (54, 56, 58 or 60°C) and held for a required pre-established time.…”

The Effect of Lysozyme on the Apparent Heat Resistance of Nonproteolytic Type B Clostridium Botulinum

“…Cassier and Sebald (1969) reported that apparently nonviable heated spores of Clostridium perfringens could be recovered in a medium containing lysozyme. Additional research confirmed that there was greater recovery of heated C. perfringens spores in media containing lysozyme (Adams 1973;Barach et aL 1974;Bradshaw et al 1977;Duncan et aL 1972). Addition of lysozyme to the recovery medium increased the apparent heat resistance of C. perfringens heated in phosphate buffer (Bradshaw et al 1977).…”

Opinion of the Scientific Panel on biological hazards (BIOHAZ) related to the public health risks of feeding farmed animals with ready‐to‐use dairy products without further treatment

“…Table 10 shows the effect of the temperature on some microorganisms in milk. 20 OJ L 330, 5.12.1998, p. 32 (Evans et al, 1970;Bradshaw et al, 1977;Lovett et al, 1982;Sung and Collins 1998;Walstra et al, 1999;Montville et al, 2005). In general, microorganisms display considerable differences in heat resistance, although the thermal process is designed to target the most resistant microorganism.…”