A Challenge of Pasteurized Process Cheese Spread with Clostridium botulinum spores.

Pasteurized process cheese spread with pimientos, packaged in glass jars, inoculated during processing with 1000 spores of Clostridium botulinum per gram, developed neither gas nor toxin at 52 or 54% moisture when sodium phosphate was used as the emulsifier. When sodium citrate was the emulsifier, the product developed gas at 52% moisture and became toxic at 54%. At 58% moisture the product became gassy and toxic with either emulsifier. Since the product is commercially manufactured at 52% moisture with phosphate emulsifier, a substantial margin of safety exists.