Abstract:
One-dimensional infrared spectroscopy, the second derivative infrared spectroscopy, two-dimensional infrared correlation spectrometry, thermogravimetric analysis, and differential scanning calorimetry were used for characterization of 2 samples (the fruit and pomace of
Sambucus williamsii Hance ) and their fat-/water-soluble extracts, achieving quick identification of the 2 samples. As found by the results from infrared spectrometry analysis, the one-dimensional infrared spectra of the 2 samples were similar, and the vibration absorption peak of the benzene ring in the pomace was more pronounced than that in the fruit in the second derivative plot. In the two-dimensional infrared correlation spectra, there were 6 automatic peaks in the fruit and 4 automatic peaks in the pomace, and the corresponding wave numbers of the automatic peaks were inconsistent. The absorption peaks at 1 711, 1 464, 1 121 cm
−1 were observed in the one-dimensional infrared spectrum of the fat-soluble extract of the fruit, while they did not appear in the pomace. However, some absorption peaks in the second derivative plot were not as obvious as those in the pomace, and there was a significant difference in the number and intensity of automatic peaks in the two-dimensional infrared correlation spectra of the fat-soluble extract of the 2 samples. The 3 infrared spectra of the water-soluble extracts from the two samples were basically similar and could not be used for identification of the 2 samples. In thermal analysis, the overall trends of the thermogravimetric and differential thermal curves of the 2 samples were consistent, but there were differences in the peak shape and peak value of the differential thermal curves. The differential scanning calorimetry curves of the 2 samples had two broad exothermic peaks, but the peak temperature of the pomace was lower than that of the fruit. The pomace had a small shoulder peak (458 ℃) near the exothermic peak at 423 ℃, which could be used as a characteristic peak of the pomace.