Determination of odor properties of ortho- and para-halogenated phenols

Many halogenated compounds have been identified previously as off-flavor-causing substances. Despite these substances being described in the literature several times, still no complete documentation of the odor properties is available. In this study the odor characteristics and odor threshold concentrations in air (OTC) of ortho- and para-halogenated phenols, and the corresponding di-halogenated phenols, were investigated systematically. The results showed that ortho-halogenated compounds tend to elicit a medicinal odor and the smell of para-halogenatad compounds was mostly fecal and horse stable-like, comparable to that of 4-methylphenol. The OTCs of the substance groups increased in the following order: ortho-halogenated phenol, para-halogenated phenol, and di-halogenated phenols.