Butylated hydroxyanisole (BHA) was inhibitory to growth of three proteolytic strains of Clostridium botulinum in prereduced thiotone yeast-extract glucose medium (TYG) (pH 7.0) at 37 C. There was outgrowth and toxin production by strain 10755A spores when 25 ppm of BHA was present in the medium, whereas growth was inhibited by 50 ppm of BHA. Strains 62A and 213B were inhibited by 25 ppm of BHA throughout an incubation period of 7 days. Butylated hydroxytoluene (BHT) and propyl gallate (PG) were less effective in inhibiting outgrowth of C. botulinum spores than was BHA. Spore outgrowth and toxin production were inhibited in the presence of 200 ppm of BHT in the TYG. PG exhibited the least inhibitory activity of the antioxidants tested. None of the levels (25 to 200 ppm) of PG tested delayed outgrowth or toxin formation for more than 24 h.
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