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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #306406
Title: High-throughput Raman chemical imaging for evaluating food safety and quality

Author
item QIN, JIANWEI - US Department Of Agriculture (USDA)
item Chao, Kuanglin - Kevin Chao
item Kim, Moon

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/20/2014
Publication Date: 7/18/2014
Citation: Qin, J., Chao, K., Kim, M.S. 2014. High-throughput Raman chemical imaging for evaluating food safety and quality. Meeting Abstract. Proceedings SPIE 9108, Sensing for Agriculture and Food Quality and Safety VI, 91080F.

Interpretive Summary: Evaluating food safety and quality becomes more important in food production as food producers need to comply with more strict rules of regulatory agencies and satisfy customers’ demands of more safe and higher quality foods. Traditional methods of inspecting end products only have been being gradually replaced by systematic approaches that require food ingredients and materials being examined at every step along the production chain. Novel techniques that are capable of performing inspections effectively and efficiently will have great potential to be used to tackle real-world food safety and quality problems. Raman chemical imaging (RCI) technique is capable of visualizing composition, distribution, and morphology of a target, which has great potential for food safety and quality evaluation. One major restriction of commercial RCI instruments is that they generally conduct measurements at subcentimeter scales. Such spatial coverage cannot be used for inspecting large sample areas. To remedy the lack of tools for macro-scale RCI, we developed a line-scan high-throughput Raman imaging system. The system utilizes a line laser as excitation source. The laser unit uses a scanning mirror to spread a high-intensity point laser to generate a laser line. A beamsplitter reflects the laser to form a 24 cm long excitation line normally incident on the sample surface. Raman signals are collected by a detection module consisting of an imaging spectrograph and a CCD camera. A hypercube data is accumulated line by line as a positioning table moves the samples transversely through the laser line. An example application for authenticating milk powder was presented to demonstrate the system performance. Chemical images were generated in real time for visualizing two adulterants (melamine and dicyandiamide) mixed in the milk powder. The system and method developed in this study is promising to have more applications for evaluating food safety and quality. The technique would benefit food processors in ensuring the safety and quality of their products and also regulatory agencies (e.g., FDA and USDA FSIS) with an interest in enforcing standards of food safety and quality.

Technical Abstract: A line-scan hyperspectral system was developed to enable Raman chemical imaging for large sample areas. A custom-designed 785 nm line-laser based on a scanning mirror serves as an excitation source. A 45° dichroic beamsplitter reflects the laser light to form a 24 cm × 1 mm excitation line normally incident on the sample surface. Raman signals along the laser line are collected by a detection module consisting of a dispersive imaging spectrograph and a CCD camera. A hypercube is accumulated line by line as a motorized table moves the samples transversely through the laser line. The system covers a Raman shift range of –648.7–2889.0 cm–1 and a 23 cm wide area. An example application, for authenticating milk powder, was presented to demonstrate the system performance. In four minutes, the system acquired a 512×110×1024 hypercube (56,320 spectra) from four 47-mm-diameter Petri dishes containing four powder samples. Chemical images were created for detecting two adulterants (melamine and dicyandiamide) that had been mixed into the milk powder.