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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF DETECTION TECHNOLOGIES FOR TOXINS AND THEIR VALIDATION IN FOOD MATRICES Title: Global challenges/chemistry solutions: Promoting personal safety and national security

Authors
item Carter, John
item He, Xiaohua

Submitted to: American Chemical Society Symposium Series
Publication Type: Popular Publication
Publication Acceptance Date: July 2, 2008
Publication Date: N/A

Technical Abstract: Joe Alper: Can you provide a little background about why there is a need for this type of assay? Mark Carter: Ricin is considered a biosecurity threat agent. A more efficient detection method was required. Joe Alper: How are these type of assays done today, or are current methods unsuitable for this type of screening? Mark Carter: Immunochemical assays are available. However, they are unsuitable for use with complex foods, such as hot dogs or powdered eggs. Animal tests are simple but expensive, and enzymatic tests are subject to interference by food. Joe Alper: Can you explain, in lay terms, how this assay works to detect ricin? Mark Carter: Ricin is a protein toxin found in castor beans. The RT-PCR test we developed doesn't actually detect the ricin toxin, itself. Instead it sensitively detects castor bean DNA, which is present in partially purified preparations of ricin. Joe Alper: Is quantitative PCR more broadly applicable in the area of food safety? For example, would this technology be useful for routine use in testing ground beef or produce for bacterial contamination? Mark Carter: Q-PCR is not sensitive enough to directly detect most food-borne pathogens. Culture enrichment is required, which amplifies the amount of nucleic acids (DNA/RNA). Non-quantitative PCR and other sequence-related molecular technologies are quite useful for food safety, after amplification. These techniques already support traditional microbiological tests for food-borne pathogens, and they are beginning to replace some of them. Federal regulatory agencies are limited to the use of methods proven to be equivalent or better than current technologies. Joe Alper: Do you think that combining microfluidic technology with quantitative PCR could lead to inexpensive technology for food safety applications? Mark Carter: Many people are working to develop high-tech microfluidic molecular assays that are portable. Similar technology is already in use for aerosol sampling and first-response "presumptive" results. Microfluidic and Q-PCR technologies could be linked sequentially, thus eliminating a two-stage assay. Thus they have the potential for providing a faster and more definitive result, coupled with reduced expense which is particularly critical for routine food safety analysis.

Last Modified: 8/1/2014
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