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Title: SPECTRAL LIBRARY SEARCHING: MID-INFRARED VERSUS NEAR-INFRARED SPECTRA OF NEAT FOOD INGREDIENT POWDERS.

Author
item REEVES III, JAMES
item ZAPF, CHARLES - MCCORMICK & COMP, INC.

Submitted to: Journal of Applied Spectroscopy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Spectroscopy is the study of how light interacts with materials. By using light of specific types (i.e., blue versus red) and examining the interaction with different materials it is often possible to determine the composition of the material in question, or to classify the material (discriminate analysis). Near- and mid- infrared are types of light beyond the ability of humans to see (what we feel as heat), and both have been used for some of these purposes. The objective of this work was to determine the potential of using mid- or near-infrared spectra (graphical representation of interaction between the specific light and a given material) to construct food ingredient spectral libraries (groups of spectra of various materials for use in comparisons) for product identification and checking. Samples (106) consisting of buttermilk, dehydrated onion, cheese and milk-egg powders, wheat flours, and two powdered seasonings were examined in the mid-infrared and in the near-infrared using several different spectrometers (instruments designed to study the interaction of light with different materials). Results showed that searches could be designed which correctly matched all unknowns with a similar sample (i.e., wheat flours with other flours and not with cheese dressings) using either near- or mid-infrared light. Thus, results demonstrated that near- or mid-infrared spectral libraries of powdered food ingredients can be used for product identification and checking.

Technical Abstract: The objective was to determine the potential of using mid- or near-infrared diffuse reflectance spectra to construct food ingredient spectral libraries for product identification and checking. Samples (106) consisting of buttermilk, dehydrated onion, cheese and milk-egg powders, wheat flours, and two powdered seasonings were scanned (neat powders, diffuse reflectance) at 4 and 16 cm-1 resolution in the mid-infrared on a Digi-Lab FTS-60 and a Perkin Elmer Model 2000, and in the near-infrared, FTS-60 (4 and 16 cm-1 resolution) and Pacific Scientific model 6500 scanning monochromator (10 nm bandwidth). A custom made sample transport device was used on the FTS-60, a rotating sample cup on the NIRSystems 6500 and a stationary cell for the Perkin Elmer 2000. Every third sample of each group was used as a test sample and searched against a library containing the remaining samples. Results showed that only full spectrum based searches using Euclidian distance or correlation (with or without a first derivative) were useful. All unknowns were correctly matched using near- infrared spectra generated on either the scanning monochromator or the FTS- 60 (4 cm-1 resolution) or using any of the mid-infrared spectra. Results demonstrated that near- or mid-infrared spectral libraries or powdered food ingredients can be used for product identification and checking.