In theory, infrared devices can deliver hundreds of readings, though "the practical limitation for most of these instruments is three, and it's usually two," notes Thermo Fisher's Cash. Nonetheless, quantifying fat and protein levels in milk or solids and oils in peanut butter with a single device is appealing.
"The simplicity of infrared and its ability to measure several things gives end users more bang for the buck," says Techniblend's Deubel. The newer devices also are less obtrusive than instruments that rely on a slip stream of product to conduct evaluations. Pump failure and vibration-distortion problems are eliminated, and newer devices feature solid state construction and probes that barely dip into the product stream.
Deubel's firm is working with one infrared supplier on development of an infrared sensor that could be used with diet soft drinks. Instruments that measure brix are of little use in the absence of sugar, so developers are focusing on the titratable acidity of diet beverages. Currently, that is done off line. "We're still involved in mapping the signature of a diet cola and making sure the results are repeatable and it doesn't take a Ph.D. to set up the instrument," he says.
Quantifying complex streams
While most sensor technology is best suited for a fluid stream, guided microwave spectroscopy (GMS) is finding a niche with ground beef. The technology excels at moisture analysis and first was applied 20 years ago at a grain milling operation. But it also can accurately measure both fat and lean constituents, based on the amplitude and frequency of the waves transmitted between two points.
Thermo Fisher introduced its GMS solution nine years ago, though extensive refinements are reflected in the E scan analyzer. The instrument often is mounted at the end of grinder to ensure lean content is in spec. "If you can save 1 percent giveaway on a grinder, it's worth a couple hundred dollars an hour, and the instrument provides a payback pretty quickly," Cash points out. The unit also has been used to measure fat in milk, with results close to the Mojonnier lab method. Mojonnier calculates fat by weight to within 0.03 percent; the GMS analyzer has been demonstrated at 0.05 percent.
Recalibration is the limiting factor with all these devices and helps explain why in-line sensors are more common in other industries. Raw material variability is a fact of life in food production. "Unlike the ingredients in shampoo, food is not a chemical, and it's not going to be the same every day," says Cash. If an ingredient's signature falls outside the fingerprint calibrated for the device, feedback data will not be reliable without recalibration.
Most lab technicians are unfamiliar with GMS, but the same can't be said of infrared. Cognizant of that, PerkinElmer Inc. recently commercialized a mid-infrared at-line instrument for trans-fat analysis. Until now, gas chromatographic methods requiring transesterfication in sample preparation were necessary.
Those lab analyses produce more comprehensive results on the types of fat in a product, allows Robert Packer, food solutions development leader in PerkinElmer's Shelton, Conn., office, but partially hydrogenated fats are the focus of public health concerns. The new instrument -- about the size of a laptop and "field deployable" -- generates results in less than a minute, he says.
"It gives us the ability to put the instrument in the hands of nonscientists and get reliable results," Packer adds. "Trans-fat is an issue everywhere, and just because your plant is in North America doesn't mean your fats and oils aren't coming from India or other markets where trans-fat levels are very high."
This article originally appeared in our July issue of Food Processing magazine.