Research on Overall Assessment of Royal Jelly Freshness by FTIR Spectroscopy
WU Li-ming1, 2, ZHOU Qun3, ZHAO Jing1, SUN Su-qin3*, HU Fu-liang2
1. Institute of Apicultural Research, the Chinese Academy of Agricultural Sciences, Beijing 100081, China 2. College of Animal Science, Zhejiang University, Hangzhou 310029, China 3. Key Laboratory of Bioorganic Phosphorus Chemistry and Chemistry Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China
Abstract：Fourier transform infrared spectra (FTIR) of royal jelly (RJ) stored at different temperature and after different storage periods were measured，a series of correlation analysis among the spectra were carried out by using the spectra of new-harvested RJ as a standard. The results showed that the correlation coefficient of amide band Ⅰ and the relative intensity ratios of I1 647/I1 541, I1 647/I1 409, I1 647/I1 247and I1 647/I1 054 of RJ samples’ spectra decreased with extension of storage time and temperature, and existed good linear correlations with the storage time, with the order of their change extent being 28 ℃＞16 ℃＞4 ℃＞-18 ℃. According to the spectra change laws and practical experiences of RJ storage, the correlation coefficient of amide band Ⅰ and four relative intensity ratios I1 647/I1 541, I1 647/I1 409, I1 647/I1 247and I1 647/I1 054 were selected as assessment indexes of RJ freshness. The threshold value of correlation coefficient was set to be 0.910 0, and the threshold values of the four relative intensity ratios were set to be 1.744, 2.430, 3.345 and 1.412 respectively. Once one or more indexes are lower than the corresponding threshold values, the RJ sample can be considered as a stale sample. So, FTIR spectroscopy combined with several data-processing methods would be an effective method for overall assessing the freshness of RJ.
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