Nothing like a good pork chop

Using NIR hyperspectral imaging, Irish scientists have shown they can display the protein, fat and water content of whole pork chops, producing an objective way to determine the quality of meat products.

In NIR hyperspectral imaging, a charged coupled device and data processing software are combined with NIR spectroscopy to produce a two-dimensional image in which each pixel contains spectral data. This allows NIR spectral data to be acquired over much a broader area than is possible with conventional NIR spectroscopy, which is especially useful when analyzing a sample with a variable chemical composition.

Meat products such as pork are just such a sample. Previous research has shown that NIR spectroscopy can accurately determine the chemical composition of meat, such as its fat content, but only when the meat is minced. In whole slices of meat, the fat concentration changes so much over the slice that measuring the concentration at just one location doesn't tell you much about the fat composition of the whole slice.

So a team led by Da-Wen Sun at the National University of Ireland's Agriculture & Food Science Centre in Dublin decided to give NIR hyperspectral imaging a go. First off, though, they merely used it as a form of conventional NIR spectroscopy, in order to analyse the protein, fat and water content of minced pork. This involved using partial least-squares regression to relate the spectral data to the concentrations of protein, fat and water measured by conventional methods, producing a model that could accurately determine these concentrations in minced pork from spectral data.

As they report in Food Chemistry, Sun and his team next applied this model to the analysis of whole pork chops by NIR hyperspectral imaging, allowing them to determine protein, fat and water concentrations from the spectral data in each pixel of the NIR image. This resulted in separate images of the protein, fat and water concentrations, showing how these concentrations varied over the chops. As an indication of the accuracy of this technique, the distribution of fat in the NIR image mirrored the distribution of fat deposits that could be clearly seen on the surface of the chops.

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