Scientists at Nestle Research, Switzerland have assessed the application of the Laser Direct Infrared (LDIR) imaging system as a rapid screening technology for detection, identification, and semi-quantitation of adulterants in food ingredients. Samples of skimmed milk powder (45), soy protein isolate (31), chicken meat powder (35), pea protein isolate (32), and wheat flour (6) were dry blended with nitrogen-rich adulterants and bulking agents at concentrations of 1.0–15.0% (w/w). In addition,10 samples of skimmed milk powder were wet blended with the same food adulterants at 5.0% and 10.0% (w/w). All the samples were used to check the LDIR performance. In most samples, the technology accurately identified all nitrogen-rich compounds and bulking agents present in the dry blended samples with a sensitivity of 82% for samples adulterated at 1%, and sensitivity from 92% to 100% for samples adulterated at ≥ 5% adulteration. However, the detection and identification of food adulterants in samples prepared by wet blending process was more challenging because mid-infrared technology may not be sensitive enough to detect adulterants if they are dissolved or if hidden within the particles.
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