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.
We aim to find a non-invasive methodology to evaluate meat freshness and beginning of spoilage through visible and near-infrared spectroscopy. We have used two configurations capable to sense at different probing depths. A table-top spectrophotometer equipped with an integrating sphere was utilized for a shallow probing depth (80 μm) and covered 400-1700 nm spectral range. In another configuration, a fiber-optic linear array was coupled to a portable spectrophotometer (400-1000 nm) for increasing the average probing depth up to 570 μm. According to the results, it is possible to observe the decreasing trend in the light absorbance in both visible and NIR spectral ranges showing loss of freshness and meat spoilage over time. In the visible wavelength range, absorbance changes at 540 nm and 580 nm wavelengths allow for monitoring oxymyoglobin degradation, which is associated with loss of freshness. In the NIR region, monitoring changes in the absorbance of fat (1200 nm), water (1450 nm), and proteins (1525 and 1600 nm) show promise to detect spoilage. Specifically, absorbance of the superficially located oxymyoglobin decays immediately but only after 4 hours at the depth of 0.57 mm, while absorbance of surface water and protein components experiences a steep decrease only after about 2.5 hours that could be interpreted as a beginning of the spoilage process.
The fiber-optic approach capable for real-time, non-destructive, inexpensive, and multi-component detection using a wide range of studied wavelengths is a great promise to design a compact, portable device for a variety of users at the meat supply chain.
Visible to near-infrared spectroscopy have been applied for non-invasive assessment of meat freshness. The reduction of oxymyoglobin absorbance associated with freshness drop is clearly seen in the visible range of spectra, as well as supplementary fat, water, and proteins contents variations are observed in the near-infrared range. A table-top spectrophotometer equipped with an integrating sphere was utilized for a shallow probing depth (80 μm) and covered 400-1700 nm spectral range. A fiber-optic linear array was coupled to a portable spectrophotometer (measurement range 400-1000 nm) for increasing the average probing depth up to 570 μm. The studied samples of meat experienced an immediate loss of superficial freshness, while kinetics of spoilage was detected after about 2.5 hours. The fiber-optic approach capable for sensing freshness and spoilage process shows promise for design of a compact, portable device for a variety of users at the meat supply chain.
There is a high demand to apply photonics-based techniques to day-to-day routine use by targeting food quality control, food safeties, biosecurity and other related applications. We present the results of study of freshness and spoilage of meat samples by using visible and near-infrared spectroscopy. Two different configurations of experiment capable of sensing diverse range of probing depths have been tested. A table-top spectrophotometer equipped with an integrating sphere was used in one setup providing a large light spot and two detectors to measure two different spectral ranges (400-1100 nm and 1100-1700 nm). Another experimental setup comprised a fiber-optic linear array coupled to a portable spectrophotometer (measurement range: 400-1100 nm) to increase the average probing depth. The freshness of meat samples was assessed as a decrease of oxymyoglobin content monitored by decreasing 580/560 nm absorbance ratio, while spoilage was revealed by changes of absorbance at 1200 nm (fat content), 1450 nm (water), 1525 nm and 1600 nm (proteins) over time. We found that the studied meat samples experienced a significant loss of freshness after 2.5 hours. This could be interpreted as a beginning of the spoilage process showing promise of the applied methodology for spoilage sensing and benefits of the portable approach. The current technique is capable to real-time non-destructive screening of meat samples in a wide range wavelengths. The results and data analysis are presented and discussed in frame of food safety application.
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