Vibrational characterization of functional groups in cocoa beans during roasting with Fourier transform infrared spectroscopy

Abstract

This work shows the potentiality of Fourier transformed infrared spectroscopy to evaluate the vibrational changes of functional groups during cocoa roasting. Thirty assignments were identified in the regions of vibration, double bond and fingerprint. With the second derivative, more than 50 peaks were identified in the spectrum. Trough the roasting time, changes were recorded in the intensity and not in the signals; however, the influence of the fatty content was shown when the samples were defatted. Changes during the roasting process of cocoa beans occurred in the fingerprint region, identified by signals assigned to the free amino acids, catechins, reducing sugars, and methylxantines identified principally in the second derivative of the spectrum. Infrared spectrum allowed to find structural changes in cocoa to different roasting times.