title: Volatile methoxybenzene compounds in grains with off-odors.
abstract: More than 20 volatile methoxybenzene compounds were found in a set of 745 corn, sorghum, soybean, and wheat samples obtained from official grain inspectors. Most samples containing methoxybenzenes were off-odor. By using an autosampler, volatiles were purged from whole grain at 80 degrees C, collected on Tenax, and then thermally desorbed and transferred to a gas chromatograph-mass spectrometer for separation and identification. Use of an infrared detector aided identification of some compounds, especially isomers with similar mass spectra. Samples with insect odor had 1,4-dimethoxybenzene and its 2-methyl, 2-ethyl, and 2-methoxy derivatives that appeared to be derived from 1,4-quinones, which are known (except for 2-methoxy) defensive secretions of Tribolium insects. Samples with mostly musty, sour, and/or smoke odors commonly contained methoxybenzene and 1, 2-dimethoxybenzene along with their 4-ethyl and 4-ethenyl derivatives, 4-chloro-1-methoxybenzene, and/or 2-methoxyphenol and its 4-ethyl derivative. Other methoxybenzenes were also found, including methoxy derivatives of other phenols and N-heterocyclic compounds. Co-occurrences and correlations of levels of some compounds were also reported to indicate relationships with odors and inter-relationships among compounds.
authors.affiliation: U.S. Grain Marketing Research Laboratory, Grain Marketing and Production Research Center, Agricultural Research Service, U.S. Depatment of Agriculture, 1515 College Avenue, Manhattan, Kansas 66502, USA. larry@usgmrl.ksu.edu
authors.forename: L M
authors.initials: LM
authors.lastname: Seitz
authors.forename: M S
authors.initials: MS
authors.lastname: Ram
mesh_terms: D000840:Anisoles / Q000032:analysis* / Q000737:chemistry; D002523:Edible Grain / Q000737:chemistry*; D009812:Odorants; D014835:Volatilization
chemical_list: D000840:Anisoles; C060998:anisole