Paula M. Powell, Senior Editor
Whether inspecting for E. coli O157:H7 on a slab of beef or for ethylvinylacetate
in a hot dog wrapper, manufacturers in the food processing industry are turning
more and more to photonics for help — and not just for laboratory-based detective
work. Increasingly, IR detectors and other photonics-based instruments are making
their way into the field. From farmers who are producing genetically modified grains
to beef inspectors, the draw is a combination of system compactness and testing
Often, politics fuels the demand for inspection
tools, from laser-diode-based biosensors to spectrometers. Consider the Meat and
Poultry Products Safety Improvement Act of 2002 sent recently to the Senate Agriculture
Committee. One component is the need for high-speed detection of chlorophyll on
carcasses, which could indicate the presence of E. coli. A possible solution
detects fluorescence of gastro-intestinal tract digestive metabolites, from chlorophyll
to enzymes, using a detector held close to the carcass.
Another political hot spot, especially
for the European Union, is genetically modified food. Researchers at the Grain Quality
Laboratory in Ames, Iowa, believe that near-IR spectroscopy could provide a nondestructive
testing technique that is lower in cost and less time-consuming than those now used.
Although not able to detect compounds at the DNA concentration level, a portable
spectrometer might be able to spot spectral differences from larger structural changes.
And then there’s the US-based
researcher who believes that IR imaging may someday be able to spot whether an apple
is sweet. Although this research is still preliminary, several photonics-based tools
— including machine vision-based systems — are either already in the
field or in beta testing, as illustrated by the applications that follow.