Study of the chlorogenic acid content in yerba mate (Ilex paraguariensis St. Hil.): Effect of plant fraction, processing step and harvesting season

• Yerba mate is a novel source for extraction of chlorogenic acid (CGA).
• The highest CGA content was found in freshly harvested (green) yerba mate.
• CGA content in leaves and stems of yerba mate was almost similar.
• CGA content in yerba mate decreased during the harvesting season.
• Green yerba mate stems, a residue in yerba mate industry, is a novel CGA source.

Chlorogenic acid (CGA) is a fine chemical used in different food and pharmaceutical industries. CGA is currently extracted from various plant materials, particularly green coffee beans. Yerba mate (Ilex paraguariensis St. Hil.) contains significant amounts of CGA with very low levels of extraction interfering substances (fatty materials). Both of these reasons prompted us to evaluate yerba mate as a novel source for extraction of this compound.CGA content was quantified in various yerba mate fractions during different processing steps, and in samples taken from two companies at early and late harvesting seasons. Samples were exhaustively extracted with hot water and total CGA content (including its three isomeric compounds) was determined by HPLC. Total CGA content (on a dry weight basis) ranged from 45.8 ± 0.4 to 80.8 ± 1.0 g CGA kg−1 of leaves and from 31.6 ± 0.6 to 78.9 ± 5.3 g CGA kg−1 of stems. A substantial reduction in CGA content was found along the processing steps. The highest CGA content was found in samples from freshly harvested (green) yerba mate, for both leaves and stems; with no significant differences in their CGA content (P < 0.05). CGA content at the early harvesting season was substantially higher to that obtained at the end of the harvesting season, for both green leaves and stems.Green stems, a residue from yerba mate processing obtained at the early harvesting season, could be considered as a promising and valuable raw material for the production of CGA-enriched extracts.