[FTIR assessment of the secondary structure of proteins in royal jelly under different storage conditions].

The quality of royal jelly has a high positive correlation with its storage periods and temperature. In the present paper, Fourier transform infrared spectra (FTIR) of royal jelly was measured with different temperatures and storage periods, and the compositions of the secondary structure of protein were determined by curve-fitting analysis of the amide I bands in the FTIR spectra. The results showed that the spectral differences were observed among these types of samples, the composition of the secondary structures of protein exhibited extreme difference, and the rate of alpha-helix decreased and beta-sheet increased dramatically with the increase in storage temperature and periods. The content of beta-turn also tended to increase, and the order of their change extent was 28 degrees C > 16 degrees C > 4 degrees C > -18 degrees C. These results met the theory that royal jelly should be kept under lower temperature. So, FTIR spectroscopy combined with several data-processing methods, such as secondary derivative, deconvolution, and curve fitting would be an effective method for assessing the quality and freshness of royal jelly.