Volatile compounds in butter oil: V. The quantitative estimation of phenol,o-methoxyphenol,m- andp-cresol, indole and skatole by cold-finger molecular distillation

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Abstract
Summary: Phenol,o-methoxyphenol,m- andp-cresol, indole and skatole have been isolated from good quality butter oil by cold-finger molecular distillation, and separated into phenolic and indolic fractions by solvent extraction and silicic-acid column chromatography. The individual compounds were quantitatively estimated by gas chromatography. When phenol,o-methoxyphenol,m- and;p-cresol, indole and skatole were added to volatile-free butter oil, their recoveries were 94, 47, 90, 75, 71 and 61% respectively. The technique, when applied to fresh butter oil, gave the following ranges of values for the natural levels of these compounds: phenol 0·005–0·022,o-methoxyphenol 0·002–0·10,m-cresol 0·002–0·010,p-cresol 0·002–0·004, indole 0·07–0·13, skatole 0·16–0·22 ppm of butter oil. The results, when compared with flavour threshold studies, showed that indole and skatole are important contributors to the natural flavour of butter oil, but that phenolic compounds are of only borderline significance.