The effect of chlorine on the viability of clostridial spores

Summary A study was made of the effect of chlorine on eight strains of clostridia. Aqueous spore suspensions were treated at 10°C with 0.5 and 5 p.p.m. (mg/1) of free available chlorine and 200 p.p.m. of combined available chlorine (Chloramine T). Clostridium welchii was found to be the most resistant of the species studied and Cl. bifermentans the least resistant. With single strains of these two species it was found that spores which survived treatment with 5 p.p.m. of free chlorine (pH 8.3) were more sensitive to heating between 60–80°C than untreated spores, but there was no change in the optimum temperature range for growth after chlorine treatment. The chlorine‐resistance of clostridial spores is discussed in relation to the processing of poultry carcasses.