Near-Infrared Technology Measures Beef Fat Better

By Jill Lee
March 11, 1998

Shining invisible light on a hamburger patty could lead to a safer, cheaper, faster and more environmentally friendly laboratory method for figuring out how much saturated fat the burger holds.

The Food and Drug Administration regulates the chemical methods of fat analysis now widely used by the food industry for quality control in recipes as well as for obtaining fat values published on all food labels. Health concerns over saturated fats have made this an important issue with consumers.

But the current methods have drawbacks, such as disposal problems posed by chemicals used in the analysis. Now scientists at the Agricultural Research Service in Athens, Ga., are using a non-chemical alternative--a technology called NIR, or Near-infrared Spectroscopy. Near-infrared light waves are just beyond the visible part of the light spectrum.

To further develop this technology, ARS has entered into a cooperative research and development agreement with Foss North America of Eden Prairie, Minn., an international supplier of automated rapid analysis tools for the food and agriculture industries.

Today's chemical method takes two days to yield results. First, technicians use petroleum ether to extract fat from a food sample. Then they inject a portion of the fat-ether solution into a gas chromatograph. It separates saturated from non-saturated fats and calculates their percentages. The instrument burns the sample used for analysis, but most of the sample left from the extraction must be disposed of as hazardous waste.

The NIR approach can measure fat levels as low as 1 percent, well within FDA requirements for precision. The approach takes less than two minutes and uses no ether or other hazardous chemicals. A food sample is exposed to near-infrared light waves. Saturated fat reflects the NIR wavelengths differently from other food components, including other fats. A computer measures the sample's absorbance--the light energy that passes through the sample. It then compares the data with information from samples with a known fat content.

ARS researchers analyzed 302 samples of neck beef to compare speed, accuracy and convenience of NIR versus traditional chemical analysis. ARS and Foss plan to develop similar fat analysis techniques for chicken, sausage and pork. They will also compile a database to include protein and fat data on several meat items.

Scientific contact: William R. Windham, ARS Quality Assurance Research Unit, Richard B. Russell Agricultural Research Center, Athens, GA 30605, phone (706) 546-3513, fax (706) 546-3607, bobw@athens.net.