Total Phenolic Contents and Antioxidant Activity in Oxidized Leaves of Mate (Ilex paraguariensis St. Hil)

Ilex paraguariensis is a native species to South America. Its economic importance is in the use of its leaves and twigs in the processing of a product popularly known as "chimarrão". The aim of this study was to evaluate the correlations between some physico-chemical process parameters in the oxidation of I. paraguariensis leaves oxidation. The leaves of Maté with age 1.0, 6.5 and 12.0 months were subjected to an oxidation process for 3 h under different relative humidity conditions (80, 90 and 99%) at 26°C. The extracts were evaluated using the experimental design techniques to maximize the oxidation conditions for the total polyphenols, antioxidant capacity, water activity and color. The condition of 90% humidity and leaf age 6.5 months resulted in lower lightness and yellow color of the product. Green color was not significantly influenced by the studied parameters. The highest levels of total phenols and antioxidant potential were found when the leaf age was one month and humidity was 90%. Thus, it could be concluded that the air humidity of the chamber and leaf age influenced the oxidation process of the leaves of Maté as well as the antioxidant capacity of the extract obtained.

Physico-chemical characterization of Ilex paraguariensis St. Hil. during the maturation

In Brazil, yerba mate is consumed after processing; however, in Chile and Uruguay, the consumers prefer the cured product, which acquires a yellow color. For that yerba-mate is stored for a period of six months to one year, which increases the cost of the final product for the overseas market. This study evaluated the effect of humidity and temperature in maturation chamber on the time required for the product to get this characteristic. The changes in the color, pH, moisture and water activity were evaluated during the time of storage in different conditions of temperature and humidity. Yerba-mate subjected to higher temperature and humidity showed nearest color of the product submitted to natural storage. The loss of green color was related to the reduction in pH and increase in the moisture of the samples. The higher humidity allowed the mate to reach conditions near to market requirements abroad in approximately 60 days of maturation.