|Liu, Yongliang - UNIV OF GEORGIA|
|Barton Ii, Franklin|
Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 24, 2003
Publication Date: January 16, 2004
Citation: Liu, Y., Barton Ii, F.E., Lyon, B.G., Windham, W.R., Lyon, C.E. 2004. Two-dimensional correlation analysis of visible/near-infrared spectral intensity variations of chicken breasts with various chilled and frozen storages. Journal of Agriculture and Food Chemistry. 52:505-510. Interpretive Summary: In spite of the tremendous growth in the volume of frozen poultry, labeling of "fresh" or "frozen" can be controversial because the measurable basis for defining these terms has been temperature, either the product and/or of the environmental chamber containing the product. Determination of "fresh" or "frozen" that are generally used by consumers can have several connotations. One of them relates to the physical state of the product (soft = fresh; hard = frozen). Meanwhile, from a regulatory standpoint, USDA's Food Safety and Inspection Service (FSIS) is responsible for ensuring that meat and poultry products are safe and accurately labeled. The labeling of poultry as "fresh" or "frozen" was determined to be a truth-in-labeling issue rather than a safety issue because at normal freezer temperatures most bacterial do not multiply. Both consumer connotations and regulatory requirements are based on different concepts; one being perception of quality, the other being temperature measurement. An instrumental approach to quality measurement is the use of visible / near infrared (NIR) spectroscopy to predict chemical (moisture, fat, and protein), tenderness, color and sensory (juiciness and chewiness) attributes in meats. However, to further improve the applications of visible/NIR technology, it is necessary to explore the fundamental visible/NIR spectral features of chicken meats with different storage time and temperature treatments. Here we present the results of applying two-dimensional (2D) correlation analysis in the characterization of visible/NIR spectral variation of chicken meats induced by either storage time-/temperature- regime or shear force values. The outcome will not only strengthen the scientific understanding of meat structure, but also be able to elucidate the sequential changes occurring in meats such as discoloration and tenderization development. Researchers working on visible/NIR and imaging spectroscopy of food and agricultural products will benefit from the findings of this research.
Technical Abstract: Generalized two-dimensional (2D) correlation analysis of visible/NIR spectra was performed to characterize the spectral intensity variations of chicken muscles induced by either storage time- / temperature- regime or shear force values. The results showed that intensities of two visible bands at 445 and 560 nm increase with the storage temperature under an identical treatment, possibly indicating a color change due to frozen storage. The 2D NIR correlation spectra indicated that all NIR bands reduce their spectral intensities, probably due to the water loss and compositional alterations during frozen-thaw process as well as the tenderization development in muscle storage. The heterospectra correlating the spectral bands in both visible and NIR regions exhibited a strong correlation, and suggested the sequential change between color and other developments in muscles. In addition, shear value-induced NIR spectral intensity variations detected the significant differences in spectral feature between tender and tough muscles.