A study of gelatin by IR spectroscopy

Samples of freshly prepared soluble, naturally aged soluble, and insoluble gelatins (an accumulation of glue taken from a wooden sculpture of the XVth century) before and after heating at 210°C have been investigated by IR spectroscopy. The IR spectra of the samples before heating consisted of the characteristic spectra of collagen or gelatin although there were differences in the 1380–1460 cm−1 region of the spectra. After the samples had been heated, the IR spectra of the soluble gelatins differed from those of the unheated samples. The changes in the IR spectra are discussed in connection with the probable structural rearrangements taking place in the natural ageing of gelatin.