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ARS Home » Research » Publications at this Location » Publication #126087
Title: DETECTION OF 2,4,6-TRICHLOROANISOLE IN MICROORGANISM-FREE IRRADIATED NONPROCESSED DRY-ON-THE-VINE RAISINS BY SOLID PHASE MICROEXTRACTION AND GC-MS

Author
item Aung, Louis
item Jenner, Joel
item Fouse, David

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2003
Publication Date: 7/9/2003
Citation: AUNG, L.H., JENNER, J.F., FOUSE, D.C. DETECTION OF 2,4,6-TRICHLOROANISOLE IN MICROORGANISM-FREE IRRADIATED NONPROCESSED DRY-ON-THE-VINE RAISINS BY SOLID PHASE MICROEXTRACTION AND GC-MS. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2003.

Interpretive Summary: California is a major raisin producer and its annual export of raisins exceeds $200 million. In order to be competitive in the global marketplace, the quality of raisins must be maintained. Raisins produced worldwide have been reported on different occasions to be contaminated by off-flavor tainting organic compounds of complex origin. Irradiated dry- on-the-vine raisins freed of microorganisms were shown to produce very minute amounts (parts per trillion) of chloroanisole compound which can be dissipated by proper ventilation. Understanding the source, amount, and manner of production of the tainting compounds can facilitate and aid in the maintenance of raisin quality for sale and consumption.

Technical Abstract: The occurrence of 2, 4, 6-trichloroanisole (TCA) in irradiated nonprocessed dry-on-the-vine (DOV) raisins and Thompson Seedless sun-dried raisins extracted by solid phase microextraction (SPME) was confirmed using gas- liquid chromatography/mass spectrometry (GC/MS). The 42 kGy dose irradiated DOV and Thompson Seedless raisins incubated in 5 growth media were shown to be free of microorganisms. The quantity of TCA in the irradiated raisins was 0.265 +/- 0.202 ng/kg compared with 0.338 +/- 0.311 ng/kg in non-irradiated samples, and DOV cane cut raisin selections B37-48 and C51-110 had significantly higher TCA than B1-88, B37-48 without cane cut and Thompson Seedless. The SPME fibre (divinylbenzene/carboxen/polydimethylsiloxane) method was simpler, quicker, and several times more efficient than the Likens-Nickerson extraction method for TCA determination. The biochemical mechanism of TCA production in raisin grape is unknown, but information of abundant phenolic substrate in grape berry, the presence of methyltransferases in Vitis tissues and chlorinating system in the biochemical literature provide a plausible basis for further investigation of the process.