Cereal Chem. 73 (6):744-750  |  VIEW ARTICLE

Nonwheat Grains and Products

Volatile Compounds and Odors in Grain Sorghum Infested with Common Storage Insects.

L. M. Seitz (1,2) and D. B. Sauer (1). (1) U. S. Grain Marketing Research Laboratory, Grain Marketing and Production Research Center. USDA, Agricultural Research Service, 1515 College Avenue, Manhattan, KS 66502. Mention of firm names or trade products does not constitute endorsement by the U.S. Department of Agriculture over others not mentioned. (2) Corresponding author. E-mail: <larry@crunch.usgmrl.ksu.edu> Accepted July 23, 1996. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 1996. 

Lesser grain borer (Rhyzopertha dominica), red flour beetle (Tribolium castaneum), rice weevil (Sitophilus oryzae), saw-toothed grain beetle (Oryzaephilus surinamensis), and rusty grain beetle (Cryptolestes ferrugineus) were placed in sorghum (1 kg, 14% mc) for 5, 7, and 10 weeks at 27ºC. Infested samples were analyzed for insect numbers, frass, odor, and volatiles. Volatiles from whole grain at 60ºC were collected on Tenax absorbent, thermally desorbed, and analyzed by gas chromatography using infrared and mass detectors for component identification. Odor was assessed by sensory panels at the Federal Grain Inspection Service and in our own laboratory. Lesser grain borer caused severe off-odor and red flour beetle caused some off-odor. The other three insects caused little or no objectionable odor, even though infestation was heavy. High concentrations of 2-pentanol and the known aggregation pheromones, dominicalure 1 and 2, were consistently present in samples infested with lesser grain borer. These compounds were only a partial cause of the odor from lesser grain borer. Several metabolites from lesser grain borer not previously reported were tentatively identified. The presence and absence of some previously reported insect pheromones and metabolites are discussed.