Citation: Proch, J.; Ró ˙ zewska, A.; Orlowska, A.; Niedzielski, P. Influence of Brewing Method on the Content of Selected Elements in Yerba Mate (Ilex paraguarensis) Infusions. Foods 2023, 12, 1072. https://doi.org/10.3390/ foods12051072 Academic Editor: Elias Bou-Maroun Received: 6 February 2023 Revised: 24 February 2023 Accepted: 28 February 2023 Published: 2 March 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). foods Article Influence of Brewing Method on the Content of Selected Elements in Yerba Mate (Ilex paraguarensis) Infusions J˛ edrzej Proch , Anna Ró ˙ zewska, Aleksandra Orlowska and Przemyslaw Niedzielski * Department of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Pozna ´ nskiego 8, 61-614 Pozna ´ n, Poland * Correspondence: przemyslaw.niedzielski@amu.edu.pl Abstract: 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 ex- tractants 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. Keywords: yerba mate (Ilex paraguariensis); multielemental analysis; extraction parameters; tap water; ultrasound-assisted extraction; ICP OES 1. Introduction Yerba mate (Ilex paraguariensis A.St.–Hil.) is a subtropical, evergreen tree that grows from 8 to 15 m. The plant is native to and exclusively located in southern Brazil, northern Argentina, Paraguay, and Uruguay [1]. Dried leaves, twigs, and stems of Ilex paraguariensis are used to prepare a beverage. Yerba mate infusions are consumed widely in South America and approx. 30% of the inhabitants on this continent drink more than 1 L daily [2]. Therefore, it is one of the most commercially cultivated plants [3]. Recently, yerba mate consumption has been expanding beyond South America to Europe, Asia, North America, and Australia [4]. Its popularity reached Poland, which is noticeable in the 8-fold increased import of the raw material in 2012–2018 [2]. Due to the ratio of leaves to twigs, there are two types of yerba mate. The first kind, called “elaborada con palo”, consists of 70% leaves and 30% twigs. The second kind, called “despalada” (or rarely “elaborada sin palo”), consists of 90% leaves and 10% twigs [5]. Moreover, two different types can be distinguished according to the different pre-processing procedures used [6]. For example, green mate are obtained by brief heating (i.e., blanching) at a temperature of 300–500 ◦ C and drying. Alternatively, a roasting process (at 120 ◦ C) can be applied to dried green mate in 15 min [7]. The leaves are generally responsible for the taste and content of the active substance, while other additives (e.g., dried fruit or flower petals) can be added to improve the taste and aroma of the infusion. However, the conditions of processing procedures (i.e., blanching, roasting, drying) strongly depend on the producer and affect the taste as well as the content of various bioactive compounds in yerba mate [1,8], including nutritional quality [9]. Traditionally, vessels (gourd, matero) made of wood, calabash, or porcelain, are used to prepare yerba mate infusions. Dry twigs and leaves (usually 50 g) are put into the vessel Foods 2023, 12, 1072. https://doi.org/10.3390/foods12051072 https://www.mdpi.com/journal/foods