Elemental and Speciation Analyses of Different Brands of Yerba Mate (Ilex paraguariensis)

Changes in the Physicochemical and Bioactive Properties of Yerba Mate Depending on the Brewing Conditions

Yerba Mate drink made from dried and crushed leaves and twigs of Paraguayan holly (Ilex paraguariensis A. St.-Hil.), which is a valuable source of bioactive substances, in particular antioxidants. The available literature lacks data on changes in the content and profile of bioactive compounds such as tannins, caffeine, the phenolic acid profile of flavonoids and carotenoids, as well as total polyphenol content and antioxidant activity in Yerba Mate infusions depending on different brewing conditions, and how different brewing conditions affect the physicochemical properties of these infusions. Therefore, this study evaluated the physicochemical properties of dried and Yerba Mate infusions prepared via single and double brewing processes at 70 °C and 100 °C. The organoleptic evaluation, as well as the instrumental color measurement, showed significant changes in the total color difference (ΔE) and the L*a*b* chromatic coordinates of dried Yerba Mate samples and their infusions. Moreover, the research showed higher contents of tannins (mean 1.36 ± 0.14 g/100 g d.m.), caffeine (mean 17.79 ± 3.49 mg/g d.m.), carotenoids (mean 12.90 ± 0.44 μg/g d.m.), phenolic acids (mean 69.97 ± 7.10 mg/g d.m.), flavonoids (mean 5.47 ± 1.78 mg/g d.m.), total polyphenols (mean 55.26 ± 8.51 mg GAE/g d.m.), and antioxidant activity (mean 2031.98 ± 146.47 μM TEAC/g d.m.) in single-brewed Yerba Mate infusions compared to double-brewed (0.77 ± 0.12 g/100 g d.m., 14.28 ± 5.80 mg/g d.m., 12.67 ± 0.62 μg/g d.m., 57.75 ± 8.73 mg/g d.m., 3.64 ± 0.76 mg/g d.m., 33.44 ± 6.48 mg GAE/g d.m. and 1683.09 ± 155.34 μM TEAC/g d.m., respectively). In addition, infusions prepared at a lower temperature (70 °C) were characterized by a higher content of total polyphenols and higher antioxidant activity, in contrast to the tannin and carotenoid contents, the levels of which were higher at 100 °C than at 70 °C. Considering the high amount of bioactive ingredients, in particular antioxidants, and a wide range of health benefits, it is worth including Yerba Mate in the daily diet.

Leaves, Infusion, and Grounds-A Three-Stage Assessment of Element Content in Yerba Mate (Ilex paraguariensis) Based on the Dynamic Extraction and Mineralization of Residues

The more yerba mate infusions that are consumed, the larger the amount of grounds generated. What is more, both the infusion and the residues after brewing remain rich elements. Therefore, a strategy for the three-stage assessment of the element content was presented. A new brewing method was based on dynamic extraction, ensuring both the ease of preparing the infusion and recovering the grounds. In turn, microwave-assisted acid mineralization was used to decompose the leaves and twigs of yerba mate before and after brewing. In total, 30 products were analyzed by ICP OES in three fractions each, i.e., dry yerba mate, infusion, and grounds, to determine up to 25 elements. The elemental composition was considered in terms of the country of origin, type, or composition of yerba mate. The extraction percentages obtained with dynamic extraction were comparable to previously used ultrasound-assisted extraction, as well as data from the literature. The three-stage strategy is a novel approach in yerba mate studies, and it may be a model procedure for the laboratory preparation of yerba mate grounds (waste that can be re-used, e.g., a natural fertilizer).

Assessment on Solubility and Solid Phase Chemical Fractionation of Manganese in Hot Infusions of Green and Roasted Mate

A solid phase chemical fractionation (SPCF) of the Mn in hot infusions prepared from commercial samples of roasted (RM) and green mate (GM) using a chelating resin Chelex 100 (NH4+ form) was performed to assess the relative lability of this essential trace element (ETE). In addition, total Mn contents in the RM and GM samples and their infusions were determined by flame atomic absorption spectrometry. Total polyphenol (TP) contents and the presence of soluble melanoidins (SM) were correlated with the Mn solubility in the RM and GM infusions. From the SPCF study, it was possible to observe that the soluble Mn forms in the mate infusions were essentially associated with relatively noninert chemical species (98.4-99.7%), suggesting that they may be potentially bioavailable. In addition, the soluble Mn contents in the GM infusions were 20.5% higher than those found in the RM. Mn solubility in the (RM) infusions was highly and directly correlated (r = 0.99) with the soluble TP, while in the GM infusions, it was high and inversely correlated with soluble TP (r =  -0.87). On the other hand, Mn solubility in the RM and GM infusions was weakly correlated with the SM. It should be stressed that GM infusions can contribute with 57 and 44% more than the RM infusions to the recommended adequate intake of Mn established for females and males, respectively. Moreover, this work is the first to evaluate and compare the relative lability of Mn and its solubility in the RM and GM infusions.

Solubility of Cd, Cr, Cu, Ni, and Pb and Its Correlation with Total Polyphenols and Soluble Melanoidins in Hot Infusions of Green and Roasted Mate

The total and soluble contents of three potentially toxic elements (PTEs) (Cd, Cr, and Pb) and two essential elements (Cu and Ni) in commercial green and roasted mate (Ilex paraguariensis St. Hil.) and their hot infusions were accessed by inductively coupled plasma mass spectrometry. Total polyphenolic (TP) contents in the infusions were accessed by Folin-Ciocalteu method, and the presence of soluble melanoidins (SM) was evaluated by measuring absorbances at 420 nm. The soluble element contents in hot infusions of green mate were present in the following increasing order: Pb < Cd < Cr < Cu, and Ni. For hot infusions of roasted mate, the increasing order was: Cu < Pb < Cd < Cr < Ni. Except for Cr, hot infusions of roasted mate supply lower contents of the soluble PTEs than hot infusions of green mate. Cadmium was the only of evaluated trace element found in hot infusions of green and roasted mate as well as in some of their mate samples above the maximum allowed contents established by Brazilian legislation. Despite this, polyphenol and melanoidin contents in green and roasted mate infusions may reduce Cd bioavailability. The soluble trace elements that correlated directly with total polyphenols in hot infusions of green or roasted mate are indirectly correlated with the presence of soluble melanoidins. Moreover, this is the first study to evaluate the correlations of soluble forms of Cd, Cr, Cu, Ni, and Pb with the presence of SM and TP contents in hot infusions of green and roasted mate.

Influence of Brewing Method on the Content of Selected Elements in Yerba Mate (Ilex paraguarensis) Infusions

In this paper, the effect of the extraction method on the concentrations of selected elements in yerba mate (Ilex paraguariensis) infusions is presented. Seven pure yerba mate samples (without additives) were selected, representing various types and countries of origin. An extensive sample preparation procedure was proposed: ultrasound-assisted extraction using two types of extractants (deionized and tap water) at two different temperatures (room and 80 °C). In parallel, the above extractants and temperatures were carried out for all samples by the classical brewing method (without ultrasound). In addition, microwave-assisted acid mineralization was carried out to determine the total content. All the proposed procedures were thoroughly investigated with certified reference material (tea leaves, INCT-TL-1). For the total content of all the determined elements, acceptable recoveries (80-116%) were obtained. All digests and extracts were analyzed by simultaneous ICP OES. For the first time, it was assessed how tap water extraction affects the percentage of extracted element concentrations.

Analysis of Mercury Content in Various Types of Tea (Camellia sinensis) and Yerba Mate (Ilex paraguariensis)

Due to the content of active ingredients, teas can be used prophylactically, but most of all they are consumed for taste reasons. As with food or water, these products can be contaminated with heavy metals, including mercury. Mercury (Hg) is a toxic element, it causes many side effects in the human body depending on the form of Hg, which can include respiratory failure, kidney damage, neurological disorders. At the cellular level, Hg and its compounds lead to a disturbance of metabolism and cell death. The aim of the study was to evaluate the mercury concentration of tea (Camellia sinensis) and Yerba Mate (Ilex paraguariensis). Eighty-six samples were collected and analyzed, including the following kinds: black, green, white, Pu-erh, and Yerba Mate. The samples came from Poland. The Hg concentration was determined with an AMA 254 atomic absorption spectrometer. The study showed that the Hg content in each tea sample averaged 2.47 μg/kg. The Hg concentration in the tested types of tea differed significantly statistically (p = 0.000). It was the largest in Yerba Mate, followed by green, Pu-erh, and white tea, and was the smallest in black tea. Statistically significant differences in the Hg content (p = 0.004) were also dependent on the form of the product; in leaf tea samples, the concentration of Hg (2.54 µg/kg) was higher than in tea bags (1.16 µg/kg). The Hg concentration determined in the tested samples does not exceed the permitted EU standard. Consuming these teas poses no health risk in terms of the amount of Hg.