## 1 Introduction  
Beverages obtained by brewing various dried parts of plants (e.g., leaves, flowers, fruits or roots) are very popular in many countries. They are valued by consumers for their attractive taste and aroma as well as their positive health effects. Plant-based infusions can also replace high-sugar beverages in the diet as a part of the recommended daily fluid intake for adults [1]. One of the most popular raw materials used for the industrial production of infusions are green tea leaves and hibiscus flowers [2; 3; 4; 5]. Both raw materials are good sources of bioactive compounds. Up to 30% of the dry weight of green tea is made up of polyphenols such as flavanols, flavanols and phenolic acids. Catechins are the most significant flavonoids and make up around 10% of the dry weight basis. The biologically active catechins in green tea are catechin, epicatechin, epigallocatechin, gallocate, epigallocatechin gallate and epicatechin gallate [6]. Studies have indicated that catechins are important in weight control [7] and cancer prevention [8; 9]. They also have significant anti-inflammatory, antioxidant and chemopreverities properties [10]. Hibiscus flowers are also a good source of bioactive compounds. They are important in the prevention of civilizational diseases. In water infusions from this raw material, the following phenolic compounds were identified: derivatives of chlorogenic acid, quercetin, kaempfer and myricetin [2; 11]. Infusions obtained from red flowers also contain anthocyanins, mainly delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside [12]. Studies indicate the antioxidant, hepatotoxicity, anti-cancer and anti-diabetic activities of hibiscus extracts [4]. Currently, the high content of compounds positively affecting human health in many food products is very desirable. It is possible to manipulate the composition of the product to achieve this effect. Literature data indicate the possibility of improving the quality of infusions as well. One way is through the addition of the by-product from the fruit industry [13]. For instance, peels after pre-treatment or pomace remaining after juice production are often sources of a higher content of bioactive compounds than the final products [14]. By-products can be not only an addition to infusions, but also their base. Studies on the use of chokeberry pomace to obtain infusions were conducted by [PERSON] and [PERSON] [15]. They found that the pomace infusion contained more polyphenols and had a better flavor than the whole fruit infusion. Chokeberry is a raw material rich in phenolic compounds, especially anthocyanins and procyanidins [16]. Literature data indicate, e.g., the high antioxidant, anti-inflammatory, antidiabetic, hepatoprotective and hypotensive potential of these compounds [17; 18]. Some authors have also suggested the cardioprotective and anticancer effects of extracts from black chokeberry fruits [19; 20]. Chokeberry is often processed into nectar because its unfavorable flavor limits its consumption in its fresh form. The addition of chokeberry pomace to infusion can not only contribute to increasing the content of health-beneficial compounds, but also give the desired color from the consumer's point of view. A study by [PERSON] and [PERSON] [21] indicates that the content of anthocyanins in pomace from chokeberries may range from 239 to 384 mg/100 g. In juices, this content is significantly lower and within the range of 130 to 210 mg/100 g.  
The studies on the use of by-products in the preparation of infusions have, so far, mainly focused on ingredients such as banana peel [22], avocado peel [23], onion peel [24], dragon peel [25] and a mixture of the by-product from different sources [13]. The aspect of using dried chokeberry pomace as components of infusions has not been extensively studied. The aim of this study was to determine the effect of the addition of dried chokeberry pomace to green tea leaves or white or red hibiscus flowers on the selected quality parameters of the obtained infusions.