title: Volatile analysis of ground almonds contaminated with naturally occurring fungi.
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 whole and blanched almonds that had been picked out and labeled as inedible by processors. 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, tetramethylpyrazine, and decanal. The almond samples investigated were characteristic of a typical postharvest environment and illustrative of potential contamination within a stockpile or transport container. Volatiles indicative of fatty acid decomposition were predominant in the samples that underwent some form of blanching. The emission amounts of hexanal, heptanal, octanal, and hexanoic acid increased 3-fold in samples contaminated with aflatoxin; however, due to variability between samples they could not be considered as indicator volatiles for aflatoxin content. The emission profile of volatiles from almond kernels contaminated with naturally occurring aspergilli and associated fungi is heretofore unreported.
authors.affiliation: Plant Mycotoxin Research, Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Albany, California 94710, USA. john.beck@ars.usda.gov
authors.forename: John J
authors.initials: JJ
authors.lastname: Beck
authors.forename: Noreen E
authors.initials: NE
authors.lastname: Mahoney
authors.forename: Daniel
authors.initials: D
authors.lastname: Cook
authors.forename: Wai S
authors.initials: WS
authors.lastname: Gee
mesh_terms: D000348:Aflatoxins / Q000032:analysis / Q000378:metabolism; D005506:Food Contamination / Q000032:analysis*; D005658:Fungi / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology*; D027861:Prunus / Q000737:chemistry* / Q000382:microbiology*; D055549:Volatile Organic Compounds / Q000032:analysis*
chemical_list: D000348:Aflatoxins; D055549:Volatile Organic Compounds