Spectroscopic food tester goes to Mars

A microfabricated capillary electrophoresis instrument originally developed by researchers at the University of California, Berkeley, to look for organic molecules on future explorations of Mars could become a fast, inexpensive, portable testing device that helps millions of people avoid headaches following consumption of certain red wines, cheese, chocolate, and other aged or fermented foods.

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By Kathy Kincade

A microfabricated capillary electrophoresis instrument originally developed by researchers at the University of California, Berkeley, to look for organic molecules on future explorations of Mars could become a fast, inexpensive, portable testing device that helps millions of people avoid headaches following consumption of certain red wines, cheese, chocolate, and other aged or fermented foods.

The device—dubbed the Mars Organic Analyzer (MOA)—was originally developed for use in the European Space Agency’s 2013 ExoMars mission and will be part of the Urey instrument that will ride aboard the ExoMars rover. It is designed to detect nitrogen-based compounds known as amines, which account for 80% to 90% of the dry weight of bacterial cells.

Amines—specifically biogenic amines—are also found in many fermented foods and beverages. In fact, some people are particularly sensitive to them. Biogenic amines such as tyramine, histamine, and phenylethylamine have been known to cause nausea, headaches, and respiratory disorders. They can be particularly dangerous in people with reduced monoamine oxidase (MAO) activity or those taking MAO inhibitors because they can potentially interact and cause dangerously high blood pressure.

“These toxins can be a serious health problem and are more common than people think,” says Richard Mathies, a chemist with the University of California, Berkeley, whose lab was responsible for developing the MOA. “They are hidden in a wide variety of foods. Having a quick, convenient way to identify them will help consumers avoid them or at least limit their intake.”

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The organic analyzer developed at UC Berkeley comprises a 400 nm diode laser, an optical detection system, and electrophoresis power supplies. The diode laser excites the sample through a 430 nm dichroic beamsplitter and an objective lens.
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Existing tests for biogenic amines can take several hours, are cumbersome, and require large, expensive instruments found only in laboratories, according to Mathies. The portable microchip capillary electrophoresis device—the MOA—developed by Mathies’ group is much more compact and efficient (see figure).

In experiments described last November in Analytical Chemistry, Mathies and colleagues used the organic analyzer to analyze tyramine and histamine concentrations in a variety of wines (both red and white), beer, and sake. They labeled each sample with a fluorescent dye, separated the components by applying an electric field on the microchip, exposed the samples to a 400 nm diode-laser beam, and analyzed the resulting pattern of light. The device accurately measured the biogenic amines present in the beverages in less than five minutes. The highest levels of tyramine were found in red wine, the highest levels of histidine in sake. The beer contained only small amounts of these amines.

While the current prototype is about the size of a small briefcase, Mathies has cofounded a startup to create a PDA-size consumer version that could be used at home or in restaurants to instantly screen a food or beverage sample for the presence of these toxins. Besides beverages, the test can be used for a number of food products, including cheese, chocolate, fish, and sauerkraut. The device could also be used by industry as a quick method to monitor or limit the biogenic amine content of foods and beverages or to screen foods that have been deliberately contaminated.

“This is a great example of how technology developed for one purpose can have useful but unexpected spinoffs,” Mathies says. “Since I suffer from red-wine headaches myself, when this device is commercialized, I’ll be the first customer.”

REFERENCE

C.N. Jayarajah, et al, Analytical Chemistry 79, 8162 (November 2007).

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