Evaluation of poly (hexamethylene biguanide HC1) [hydrochloride] as a biocide in the food industry [Industrial disinfectant]

Poly (hexamethylene biguanide hydrochloride) (PHMB), an industrial disinfectant, was evaluated for potential use in the food industry following suggestions in the literature. A colorimetric test based on the reaction with nitro‐prusside reagent was found suitable for the dosimetry of this compound. In a bacteriological medium, at a concentration of 20 μg/ml, PHMB was inhibitory to Escherichia coli, less effective against Staphylococcus aureus, and practically ineffective against Pseudomonas aeruginosa. The bactericidal activity of PHMB was impaired in the presence of milk but little affected upon the addition of blood. Finally, in a toxicological test in vitro, PHMB was found to be toxic toward Chinese hamster cells, at doses similar to those required for antibacterial activity.