Assessment of pork freshness based on changes in constituting chromophores using visible to near-infrared spectroscopy

Visible to near-infrared spectroscopy has been applied for non-invasive assessment of meat freshness. The measurements were done at room temperature with non-frozen pork samples. The absorbance spectra of the main chromophores in meat including oxymyoglobin, water, fat, and protein were different enough to be identified spectrophotometrically. The decreasing trend in absorbance spectra of these components over time can be associated with freshness decay. We used two configurations, fiber-optic probes and integrating sphere, to study their efficiency in meat quality evaluation. In the integrated sphere configuration, the samples experienced an immediate smooth decrease of oxymyoglobin absorbance arising from loss of superficial freshness, while degradation kinetics of water, fat and protein absorbance were detected after about 2.5 hours. In the fiber-optic configuration capable for sensing up to 570-μm depth, the drop in oxymyoglobin absorbance started after 4.5 hours which would affect directly the color of sample associated with freshness.