Differences in physicochemical properties of yerba maté (Ilex paraguariensis) obtained using traditional and alternative manufacturing methods

Abstract

The aim of this study was to determine the drying kinetics and physicochemical properties of yerba maté obtained using three different alternative manufacturing methods and to compare these products with those of the yerba maté produced using the traditional process. Additionally, triangle tests were performed to establish whether there were sensory differences between the products studied. The assayed alternative manufacturing methods included the following: (a) zapecado using boiling water (BWZ) and (b) zapecado using steam water (SWZ), both followed by a final hot air drying step, and (c) an integral manufacturing method (zapecado + drying) using high-frequency radiation (HFR). The HFR integral method yielded a product with a higher caffeine content (>30%; p <.05) than that of traditional yerba maté. Furthermore, HFR yerba maté showed significantly higher total polyphenol content values than those of BWZ and SWZ yerba maté (>10%; p <.05). Likewise, the HFR integral method resulted in a yerba maté that was much more similar in color and with imperceptible sensory differences (p >.05) when compared to the traditional product. Practical applications: During traditional yerba maté manufacturing, freshly harvested branches of Ilex paraguariensis come into direct contact with combustion gases from the burning of forest biomass. This contributes to the formation of polycyclic aromatic hydrocarbons and their subsequent deposition in yerba maté leaves and stems. Polycyclic aromatic hydrocarbons have been proved to be carcinogenic, in addition to having other toxic effects on humans. The elimination of combustion gases as a direct source of heat in the manufacturing process of yerba maté is an emerging need. The development of alternative manufacturing methods that avoid the contact of the raw material with the products of the incomplete combustion of forest biomass burning and the subsequent implementation of these methods in the industry will guarantee a higher quality product from a food safety point of view.