CREOL, The College of Optics & Photonics

REU Student Project:

Marc Koehler
2011 U.S. Students
Advisor: Martin C. Richardson
"Laser Vibrational Spectroscopy for Food Monitoring and the Detection of Different Food Additives"
The monitoring and analysis of food constitution (nutrients, additives, and freshness) has become an urgent need for ensuring safe nutrition and healthy diet for the consumer. One type of the constituents of interest in the food is the carotenoids. Carotenoids are long strands of polyisoprenoid hydrocarbons found naturally occurring in plants and even animals, through the plants they often eat [1]. Their colors usually range from yellow to red and their origin can be natural or they can be synthesized. Their chemical structure makes them easily oxidized during the food production process. The monitoring of the natural and/or artificial addition of such food colorants has then become a great need in the field of food inspection [1].
The carotenoids analyzed in this project were ß-carotene, crocin, capsanthin, norbixin and lutein. The combination of Raman and Infrared spectroscopic signatures were used to find the different vibrational modes of each individual carotenoid as their spectral fingerprint [1]. Raman spectroscopy and infrared absorption are two complementary techniques providing information on the vibrational modes involving, respectively, a change in polarizability (usually the carbon chain of the molecule) and dipole (usually the oxygenated radicals at both ends). The combination of both spectral signatures can help providing a unique signature for each carotenoid [1].

[1] Schulz, H., M. Baranska, and R. Baranski. "Potential of NIR-FT-Raman Spectroscopy in Natural Carotenoid Analysis."Biopolymers 77 (2005): 212-221.  ...full text

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