The apparent piperine contents of black and white peppers were determined b y both a spectrophotometric method and a colorimetric procedure. The piperine contents by the latter procedure were consistently higher than that indicated b y the ultraviolet measurements. The variables causing these discrepancies in results were investigated using column fractionation of pepper extracts as well as by paper and thin-layer chromatography. Analogs of piperine with less than two conjugated ethylenic linkages could not be found in pepper extracts. However, all black and white peppers contained the piperine analog with three conjugated ethylenic linkages, piperettine. Measurements of the ultraviolet absorbances at 343 mp for piperine and at 364 mp for piperettine and calculation of the ratio of these two biochemically related constituents gave results for true piperine and piperettine contents which served to some extent as an indication of the geographical origin of a pure pepper.

Benzo[a]pyrene can be used as an index of carcinogens in smoke. A simple and rapid method has been developed for determining this substance. The dried food was extracted with ra-hexane, the hexane was then extracted with dimethyl sulfoxide, and the polynuclear hydrocarbon was displaced from this solvent into benzene by water. The benzene extract was reduced to a small volume and an aliquot was spotted on a thin-layer chromatographic plate beside spots of a standard benzo[a]pyrene solution. The plate was chroma tographed with 2,2,4-trimethyl pentane:benzene (97:3). When observed under ultraviolet light at 3660 Å, 0.002 μg of pure benzo[a]pyrene could be found and the addition of 0.01—0.05 ppm to unsmoked foods could be detected. No smoked food examined contained this level of benzo-[a]pyrene.

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