Maté (Ilex paraguariensis) Toasting Causes Chlorogenic Acids to Degrade and Incorporate into the Backbone of Melanoidins, Contributing to Their Antioxidant Activity

Mate (Hex paraguariensis) is a plant rich in chlorogenic acids (CGA) used to prepare teas elaborated with untoasted or toasted leaves. The present study was the first to investigate the effect of increasing toasting degrees, during actual industrial conditions, on mate CGA contents, their incorporation into melanoidins, and their relationship between mate melanoidins and antioxidant activity (AA). CGA contents decreased by up to 91% during toasting, and two lactones were formed. Melanoidins contents increased 73% at the beginning of toasting and decreased thereafter. UV-vis spectroscopy and nuclear magnetic resonance spectroscopy indicated the presence of proteins, polysaccharides, and CGA in the backbone of mate melanoidins. The contents of caffeic and ferulic acids bound to mate melanoidins reached a maximum at the medium toasting degree (6.2/100 g), followed by a decay thereafter. The AA of mate melanoidins was mainly correlated with phenolics and nitrogen compounds incorporated into their structure.