1a. Objectives (from AD-416):
Aflatoxin contamination of almonds and pistachios results in millions of dollars of lost product annually. Aflatoxins are metabolites produced by Aspergillus flavus and A. parasiticus, ubiquitous fungi of California tree nut orchards, and represent a grave food safety problem due to their carcinogenic attributes. Current methods of analysis involve removal and destruction of 20 kilograms of product, utilize laboratory-based methods (e.g. HPLC), are expensive, and can take weeks for results. Because aflatoxin contamination can be limited to one- or two-highly contaminated nuts, current methods do not guarantee detection of the infected nuts, thus posing serious health and safety concerns for the public. Importance and timeliness: Despite an increase in self-regulation and aflatoxin testing protocols by the almond and pistachio industry, the costly rejection of exported product continues. A reliable, early warning aspergilli detector has been cited as a critical need of the industry. The current project has the strong support of both the Almond Board of California and the California Pistachio Research Board of California. Objectives: Continue investigation of recently discovered volatile profile of germinating aspergilli spores on almond and pistachio, including volatile compounds unique to the germinating spores on these hosts; use volatile profile in conjunction with a portable GCMS system to develop a near real time portable field volatile sampling device capable of early warning detection of aspergilli infected almond and pistachio; remove aflatoxin-producing aspergilli “hot spots” from almond and pistachio stockpiles and transit containers thus decreasing human health risks and product loss as a result of Aspergillus contamination. Commitment of USDA Resources: Partial commitment of instruments and equipment for completion of project including: GC-MS, safety hoods, GC-FID, HPLC, and LC-MS. All instruments are present in SYs’ laboratories. Partial time commitment of scientist in the SY’s laboratory.
1b. Approach (from AD-416):
For first objective – continue investigation of recently discovered volatile profile of germinating aspergilli spores on almond and pistachio, including volatile compounds unique to the germinating spores on these hosts – current and preceding research has identified volatile markers of early spore germination from components of almond and pistachios. Additionally, many of these markers have been detected on the hulls of almonds. Research investigating the conditions for emission of the volatile makers will continue for the first year of the grant. For second objective – use volatile profile in conjunction with a portable GCMS system to develop a near real time portable field volatile sampling device capable of early warning detection of aspergilli infected almond and pistachio – an agreement is being formed with a portable GCMS company (Torion Technologies, Inc., the co-project director of the grant proposal) to develop a volatile collection device fitting that will connect to an existing portable GCMS. Torion Technologies will also develop the necessary software for identifying multiple signals from the contaminated almond and pistachio. For the third objective – remove aflatoxin-producing aspergilli “hot spots” from almond and pistachio stockpiles and transit containers – using the maker volatile profiles discovered by the USDA-ARS lab, apply the developed portable GCMS system to simulated and actual field conditions for detecting inoculated/contaminated almond and pistachio product.
3. Progress Report:
ARS Activities: Using volatiles from inoculated tree nut meats, ARS researchers have identified several key compounds that were passed on to the collaborator, Torion Technologies, to add to the database of the portable GC-MS instrument in their laboratories. Torion Activities: Designed custom needle trap air sample collection device for volatiles from almond and pistachio stockpiles. The needle trap serves as the primary method for introducing the sample from air collection into the portable GC-MS system. The absorbent packed needle-trap is inserted directly into the GC-MS and functions as a 1st stage concentrator that can collect enough sample in 5 minutes to detect sample concentrations as low as a few parts per billion. If needed, lower detection levels in the parts per trillion range are possible with a second stage trapping device. Samples would be collected on off-the-shelf thermal desorption tubes and transferred to the needle-trap for injection into the GC-MS. This project directly relates to Objectives 1 and 2 of the parent project.