Changes in the visible/near-infrared spectra of chicken carcasses in storage

A spectrophotometer was used to measure the visible/near-infrared (Vis/NIR) spectra of post-mortem chicken carcasses freshly slaughtered 1, 2, 3, 4, 8, 11, and 14 days after storage at 0, 4, and 20C. The spectrum of a carcass after storage was compared with the spectra of freshly slaughtered carcasses and the spectra of carcasses stored at the different temperatures. The method of comparison was performed by computing the Mahalanobis distance of the sample's second central difference spectrum from the group means of the second central difference spectra of all the carcasses measured shortly after slaughter (about 1 h) and the set of second central difference spectra of the carcasses stored at each temperature. The results showed the spectra of the chicken carcasses changed 24 h after removal from the slaughter plant, even though they were stored at 0C. The spectra of the carcasses stored at 20C were different from those of the carcasses stored at 0 and 4C. The spectra of the carcasses stored at 0 and 4C for the first 8 days remained in the same class of the spectra of the carcasses at 1 day of storage at 0C. However, the spectra changed dramatically after 8 days of storage. The pattern of change of the spectra coincided with that of the myoglobin and oxymyoglobin changes of chicken carcasses at various storage temperatures and durations. It was suggested that Vis/NIR spectroscopy has the potential to be used as a rapid, nondestructive method for monitoring the freshness of chicken carcasses.