88D-9 |
Instrumental detection of microbial infection of rice using the presence of volatile compounds. |
D. M. GREENE-MCDOWELLE1, J. R. Griffin, C. C. Grimm3, and K. L. Bett-Garber3. (1) Department of Biology, Xavier University of Louisiana, 1 Drexel Drive, New Orleans, LA 70125, (2) Food Processing & Sensory Quality, USDA-ARS-SRRC, 1100 Robert E. Lee Blvd., New Orleans, LA 70124 A common occurrence is the deleterious microbial contamination of agricultural commodities. Rapid detection of microbial contamination would ensure the safety and aid in the assessment of overall crop quality. Microbial organisms produce volatile compounds, some of which impart high flavor impact although present at concentrations in the sub parts per billion range. Our objective was to utilize the volatile compounds found in the headspace of rice and fungi to develop a rapid, instrumental method to detect and identify damaged rice as a result of fungal contamination. Aliquots of selected rice were infected with Aspergillus flavus, Fusarium grameanerum or Penicillium roqueforti and the resultant headspace compared with a control rice sample and fungi grown on potato dextrose agar. The enclosed headspace above rice was captured and analyzed for volatile compounds by solid phase microextraction - gas chromatography mass spectrometry. The chromatographic traces were compared to determine differing headspace compositions, and ultimately, to identify “signature” compounds of fungal infection. Lipid oxidation products dominated the GC trace of the non-infected rice. In addition to lipid oxidation products, the chromatographic trace of the infected rice contained 1-octen-3-ol, 1-octen-3-one, 3-octanone and limonene. In a typical sample, a 25-fold increase of 1-octen-3-ol was observed for the infected rice while 3-octanone was exclusive to the infected samples. This work shows that gross fungal infections of rice can be detected by a rapid GC/MS analysis of the volatile compounds.
Session 88D, Food Microbiology: General
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