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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICAL CONTROL OF INSECTS AND MICROORGANISMS TO PREVENT MYCOTOXIN CONTAMINATION

Location: Foodborne Toxin Detection and Prevention

Title: Volatile analysis of ground almonds contaminated with naturally occurring fungi

Authors
item Beck, John
item Mahoney, Noreen
item Cook, Daniel
item Gee, Wai

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2011
Publication Date: April 30, 2011
Repository URL: http://dx.doi.org/10.1021/jf200739a
Citation: Beck, J.J., Mahoney, N.E., Cook, D., Gee, W.S. 2011. Volatile analysis of ground almonds contaminated with naturally occurring fungi. Journal of Agricultural and Food Chemistry. 59(11):6180-6187.

Interpretive Summary: Aflatoxigenic aspergilli such as Aspergillus flavus and A. parasiticus inflict major economic damage to the tree nut industry of California, with the highest negative impact to almonds. Aspergilli and fungi in general are known to emit volatile organic compounds in varying amounts and composition dependent upon their growth media. The goal of the study was to determine the volatile emission of ground almonds from stocks of whole and blanched almond kernels naturally contaminated with typical orchard and/or processing fungi. Blanched almonds have undergone some form of heating to remove the skins. The aflatoxin content and number of colony forming units of each sample were also determined. A total of 23 compounds were consistently detected and identified. Several volatiles from the blanched almonds demonstrated significant increases when compared to the emissions of whole almonds. Several of these volatiles are considered fatty acid decomposition products and included hexanal, heptanal, octanal, nonanal, 3-octen-2-one, tetramethyl pyrazine, and decanal. The almond samples investigated were characteristic of a typical post-harvest environment and illustrative of potential contamination within a stock-pile or transport container. Volatiles indicative of fatty acid decomposition were predominant in the samples that underwent some form of blanching. No definitive conclusions could be drawn regarding indicator volatiles for aflatoxin content. An indicator volatile is compound emitted in a consistent manner such that when it is detected it would indicate the presence of certain fungus and/or microbe. The emission profile of volatiles from almond kernels contaminated with naturally occurring aspergilli and associated fungi is heretofore unreported.

Technical Abstract: Aflatoxigenic aspergilli inflict major economic damage to the tree nut industry of California, with the highest negative impact to almonds. Aspergilli and fungi in general are known to emit volatiles in varying quantity and composition dependent upon their growth media. The goal of the study was to determine the volatile emission of ground almonds from stocks of whole and blanched almond kernels naturally contaminated with typical orchard and/or processing fungi. The aflatoxin content and number of colony forming units of each sample were also determined. A total of 23 compounds were consistently detected and identified. Several volatiles from the blanched almonds demonstrated significant increases when compared to the emissions of whole almonds. Several of these volatiles are considered fatty acid decomposition products and included hexanal, heptanal, octanal, nonanal, 3-octen-2-one, tetramethyl pyrazine, and decanal. The almond samples investigated were characteristic of a typical post-harvest environment and illustrative of potential contamination within a stock-pile or transport container. Volatiles indicative of fatty acid decomposition were predominant in the samples that underwent some form of blanching. No definitive conclusions could be drawn regarding indicator volatiles for aflatoxin content. The emission profile of volatiles from almond kernels contaminated with naturally occurring aspergilli and associated fungi is heretofore unreported.

Last Modified: 9/20/2014
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