Research on Overall Assessment of Royal Jelly Freshness by FTIR Spectroscopy
Guang Pu Xue Yu Guang Pu Fen Xi, 2009 Dec;29(12):3236-40
Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100081, China. email@example.com
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 I 1 647 /I1 541, I1 647/I1 409, I1 647/I1 247 and 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 degrees C > 16 degrees C > 4 degrees C > -18 degrees C.
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 247 and 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 IRJ.