[Aging Process of Puer Black Tea Studied by FTIR Spectroscopy Combined with Curve-Fitting Analysis].

For better determination of the chemical components in the Puer black tea, Fourier transform infrared spectroscopy was used for obtaining vibrational spectra of Puer black tea at different aging time. Fourier transform infrared (FTIR) spectra indicated that the chemical components had change in Puer black tea at different aging time. The leaf of Puer black tea was a complex system, its Fourier transform infrared spectrum showed a total overlap of each absorption spectrum of various components. Each band represented an overall overlap of some characteristic absorption peaks of functional groups in the Puer black tea. In order to explore the change of characteristic absorption peaks of functional groups with aging time, the prediction positions and the number of second peaks in the range of 1900-900 cm(-1) were determined by Fourier self-deconvolution at first, and later the curve fitting analysis was performed in this overlap band. At different aging time of Puer black tea, the wave number of second peaks of amide II, tea polyphenol, pectin and polysaccharides at overlap band were assigned by curve fitting analysis. The second peak at 1520 cm(-1) was characteristic absorption band of amide II, the second peaks of tea polyphenol and pectin appeared at 1278 and 1103 cm(-1) respectively. Two second peaks at 1063 and 1037 cm(-1), corresponds mainly to glucomannan and arabinan. The relative area of these second peaks could be indicated the content of protein, tea polyphenol, pectin and polysaccharides in the Puer black tea. The results of curve fitting analysis showed that the relative area of amide II was increasing first and then decreasing, it indicated the change of protein in Puer black tea. At the same time, the content of tea polyphenol and pectin were decreased with the increase of aging time, but the glucomannan and arabinan were increased in reverse. It explained that the bitter taste was become weak and a sweet taste appeared in the tea with the increase of aging time. The present study suggested that Fourier transform infrared spectroscopy combined with curve-fitting analysis could reveal the biochemical changed of Puer black tea with the increase of aging time, and it was evidence for evaluation the quality of Puer black tea.

[Study on quality of five hybrid corn kernels by FTIR spectroscopy].

The aim of this work was to study the feasibility of evaluating quality of corn kernels using Fourier transform infrared (FTIR) spectroscopy. The spectra of five kinds of hybrid corn kernels were obtained by infrared spectrometer rapidly. The infrared spectrum between 1 776 and 952 cm(-1) was composed of absorption bands of protein, starch and lipid mainly. The absorption band of starch was strong, and the band of protein was weak. The characteristic bands of starch, protein and lipid were highly overlapped, and main information was concealed. Curve-fitting the spectrum between 1 776 and 952 cm(-1), significant information was presented. The percentage of band area at 1 051 and 1 548 cm(-1) in total band area has a linear relationship with the concentration of starch and protein. The results showed that Fourier transform infrared spectroscopy combined with curve-fitting could be used to analyse the concentration of starch and protein in corn kernel, and provides a rapid and convenient method to study hybrid corn.

[Identification of different Citrus sinensis (L.) Osbeck trees varieties using Fourier transform infrared spectroscopy and hierarchical cluster analysis].

Researched on diversity of the spring leaf samples of seven different Citrus sinensis (L.) Osbeck varieties by Fourier transform infrared (FTIR) spectroscopy technology, the results showed that the Fourier transform infrared spectra of seven varieties leaves was composited by the absorption band of cellulose and polysaccharide mainly, the wave number of characteristics absorption peaks were similar at their FTIR spectra. However, there were some differences in shape of peaks and relatively absorption intensity. The conspicuous difference was presented at the region between 1 500 and 700 cm(-1) by second derivative spectra. Through the hierarchical cluster analysis (HCA) of second derivative spectra between 1 500 and 700 cm(-1), the results showed that the clustering of the different varieties of Citrus sinensis (L.) Osbeck varieties was classification according to genetic relationship. The results showed that FTIR spectroscopy combined with hierarchical cluster analysis could be used to identify and classify of citrus varieties rapidly, it was an extension method to study on early leaves of varieties orange seedlings.

[Studies on normal and mildewy Auricularia auricular by Fourier transform infrared spectroscopy].

In order to verify the capability of Fourier transform infrared spectroscopy in food safety, Fourier transform infrared spectroscopy (FTIR) was used to obtain the spectra of normal and mildewy auricularia auricula, The result showed the frequency of hydroxyl and aliphatic absorption band in their spectra had evident differentia, with the dispersion being 23.31 and 13.41 cm(-1) respectively. The curve-fitting analysis was used for the fold peaks of hydroxyl and amido, and it presented that the content of hydroxyl and amido had evident change. The substances in the auricularia auricula generated chemical change, and Fourier transform infrared spectroscopy could show the differentia easily. The results show that Fourier transform infrared spectroscopy can provide valuable information about the auricularia auricula. It could be used as a reference method for identification of the normal and mildewy auricularia auricula.

[Differentiation of Amanita hemibapha (Berk. & Broome) Sacc. subsp. hemibapha and Amanita hemibapha var. ochracea Zhu L. Yang by Fourier transform infrared spectroscopy].

In order to demonstrate the ability of Fourier transform infrared (FTIR) spectroscopy for the differentiation of macro-fungi at variety level, FTIR spectroscopy was used to obtain vibrational spectra of Amanita hemibapha (Berk. & Broome) Sacc. subsp. hemibapha and Amanita hemibapha var. ochracea Zhu L. Yang. The results show that their spectra are very similar to each other, with a small difference in the relative intensity of absorbance. For the purpose of enhancing the spectral resolution and amplifying the differences, the first-derivative spectra and second-derivative spectra were selected for evaluating the correlation coefficients respectively. The results show that the second-derivative spectra of two fruit bodies of Amanita hemibapha (Berk. & Broome) Sacc. subsp. hemibapha and one fruit body of Amanita hemibapha var. ochracea Zhu L. Yang have obvious differences, the correlation coefficients are only 0.245 and 0.356 respectively, the second-derivative spectra of two fruit bodies of Amanita hemibapha (Berk. &Broome) Sacc. subsp. hemibapha are very similar, and the correlation coefficient is 0.865. The authors' results show that Fourier transform infrared spectroscopy in combination with correlation analysis method can be used to identify Amanita hemibapha (Berk. & Broome) Sacc. subsp. hemibapha and Amanita hemibapha var. ochracea Zhu L. Yang rapidly and accurately.

[Identification of Pu' er tea by Fourier transform infrared spectroscopy].

In the present paper, Fourier transform infrared spectroscopy (FTIR) was used to determine unzymic and zymic Pu'er tea of different grade produced in Simao, Yunan Province. Because of the different processing technology, different proportion of chemical constituents exists in the unzymic and zymic Pu'er tea. And although there is a great mass of similarity in infrared spectrum, the results still show differences in the characteristic peaks of infrared spectrum between unzymic and zymic Pu'er tea. And there is also obvious difference between unzymic Pu'er tea of different grade or zymic Pu'er tea of different grade. According to the studies of the spectral peaks and absorbance ratios, unzymic and zymic Pu'er tea can easily be identified. And different grade of unzymic and zymic Pu'er tea may be classified by the differences in the absorbance ratios of several peaks. FTIR is proved to be a rapid, simple, reliable and non-destructive qualification method, it is suitable for grade identification of Pu'er tea.