Larry M. Seitz

Analysis of Alternaria metabolites by high-pressure liquid chromatography.

A high-pressure liquid chromatogrphic (HPLC) method is described for analysis of Alternaria metabolites in grain sorghum and in cultures of Altenaria on grains. The metabolites were extracted from the sample with methanol in a blender. Ammonium sulfate solution was added to a portion of the methanol extract, and the resulting adqueous phase was partitioned first with hexane to remove oil and pigments and then with methylene chloride to extract the metabolites. A small silica gel column was usually used to clean extracts further. Metabolites were separated with Corasil II or Zorbax-SIL columns by either isooctane-tetrahydrofuran (THF) or petroleum ether-THF, with solvent programming, and detected by simultaneous monitoring of fluorescence and 350-nm absorbance. Quantitation of alternariol monomethyl ether, alternariol, and altenuene was usually based on fluorescence; less than 100 ppb of each compound could be detected. Other metabolites are mentioned briefly.

Comparison of methods for aflatoxin analysis by high-pressure liquid chromatography☆

Reversed-phase columns packed with octadecyl and phenyl reversed phases did not provide adequate separation of aflatoxins. A peculiar adsorption column provided partial separation, i.e. B1 and B2 from G1 andG2, but not B1 from B2 nor G1 from G2. A microparticulate adsorption (7icro-A) column completely separated aflatoxins B1, B2, G1, and G2. Detection was more selective at 350 nm (or 365 nm) than at 254 nm. A Fluoro Monitor Model 1209 detector (Laboratory Data Control Corp.) was more sensitive for aflatoxins G1 and G2 than for B1 and B2. Aflatoxin B1 at the 30-ppb level in yellow corn was detected with the Micro-A column and the 350-nm photometer. The limit of detection was estimated at about 10 ppb.

Volatile compounds in wheat cultivars from several locations in kansas

Abstract Five cultivars of wheat grain harvested at six Agricultural Experiment Station plots across Kansas in 1992 and 1993 were analyzed for volatiles by using a purge and trap instrument interfaced to a gas chromatograph equipped with infrared and mass spectrometric detectors. Even though odors of most of the samples were normal, more than 100 compounds were observed. Alcohols were most abundant, followed in order by aldehydes, alkanes, alkylbenzenes, ketones, methyl esters, naphthalenes, terpenes, and other miscellaneous compounds. Amounts of some volatiles differed among locations and cultivars, but none of the differences appeared to be associated with intrinsic properties of the cultivars themselves. Evidence for slight insect infestation was found in the 1992 samples.

Sensory properties of musty compounds in food

Abstract Musty aroma and flavor is a major problem in a variety of foods and packaging materials. Some compounds such as geosmin and 2-methylisoborneol have been studied in relation to water, grains, fish, and potatoes, but a variety of other compounds can result in mustiness. Thirty-four chemical compounds, including chloroanisoles, pyrazines, and aldehydes potentially related to mustiness in foods or packaging which were tested in this study. Six highly trained sensory panelists smelled each compound dissolved in propylene glycol (if soluble) at dilutions of 1000, 5000, and 10000 ppm, although some were tested at levels as low as 100 ppm or as high as 100000 ppm. A range of musty-type odors including earthy, moldy, fungal, damp basement-like, mushroomy, and fermented were found in at least some of the compounds. As expected, changes in concentration or slight modifications in functional groups resulted in large differences in character.