Submitted to: Journal of Meat Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2000
Publication Date: 3/1/2001
Interpretive Summary: At the Instrumentation and Sensing Laboratory, we have developed a visible/near-infrared (Vis/NIR) spectrophotometer system for poultry inspection that will reduce the workload of the inspectors in processing lines, improve the effectiveness of the U.S. federal safety inspection program, and increase the productivity of processing plants. However, to further improve the mathematics model and select better characteristic spectral wavelengths, it is necessary to explore the fundamental VIS/NIR spectral features of chicken meats, with the newly-developed two-dimensional (2D) correlation method. This is the fourth report in a series for systematic research on chicken meats using the above strategy. The importance of freezing of meats and the proper procedures for freezing have been considered widely, however, the subject of thawing, the opposite process to freezing, has been largely ignored. We present the results of applying 2D correlation analysis in the characterization of VIS/NIR spectral variation of thawing behavior of frozen chicken meats. The outcome will not only strengthen the scientific understanding of meat structure, but also elucidate the sequential changes occurring in meats such as the melting of ice crystals and the recovery of meat color, ultimately improving the effectiveness of poultry inspection program. Researchers working on visible/NIR spectroscopy of food and agricultural products will benefit from the findings of this research.
Technical Abstract: The thawing behavior of frozen chicken meats without exposure to air was investigated by generalized 2D Vis/NIR correlation spectroscopy. The synchronous 2D visible correlation analysis revealed that intensities of the 435 and 555 nm bands increase, probably because of the relaxation of DeoxyMb and OxyMb components, whereas, those of the 475 and 620 nm bands decrease as MetMb and SulphMb decompose into small molecules due to bacterial enzymes. The corresponding asynchronous spectra indicated that the decomposition of MetMb and SulphMb species precedes the recovery of DeoxyMb and OxyMb, and that the DeoxyMb species recovers faster than the OxyMb. Further, the asynchronous 2D NIR spectra suggested that the melting of ice crystals and the relaxation and proteolysis of proteins occurs earlier, indicating a coordination process for hydrophilic O-H and N-H groups. Moreover, strong correlation peaks correlating the bands in the visible and NIR spectral regions were observed and discussed.