We demonstrated a quality evaluation of cheeses using terahertz spectroscopy. Strip preparations of seven kinds of commercially produced cheeses were measured and the characteristic spectra were obtained. Casein, milk lipid, and sodium chloride, as dominant components of cheese, were scanned using a terahertz spectrometer based on a Fourier transform infrared spectrometer, and we found that the absorption coefficient of casein became larger than that of sodium chloride below 75 cm
-1. We analyzed the spectrum of Camembert cheese at 75.2 cm
-1 to obtain a correlation with the crude protein concentration using the Kjeldahl method, and a significant correlation was shown. However, since the shape of the terahertz spectrum of casein was different from that of defatted and dehydrated cheese, this suggested the possibility that not only the crude protein concentration but also the micro structure consisting of casein micelles or fat particles in cheese was included in the terahertz spectrum.
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