INTRODUCTIONTea (Camellia sinensis L.) is considered to be themost popular beverage in the world [1, 2]. It has beenestimated that the average daily consumption of tea isapproximately 120 mL. Poland is among the first threeEuropean countries and ten world countries in terms oftea consumption. Of several species commonly referredto as tea, the most important is Chinese tea producedfrom the Camellia sinensis leaves [3]. The chemicalcomposition of tea is highly diverse and may vary withina relatively broad range, depending on many factors(e.g. the position of leaves on the stem, growthconditions, processing methods, or brewing time) [4–6].In recent years, of great interest has been thetherapeutic activity of tea and, in particular, theantioxidant effects of its compounds, e.g. polyphenolsand flavonoids [3, 6–10]. Due to differences inprocessing technology or species composition, each typeof tea contains a different combination of biologicallyactive substances, depending on the extraction time andtemperature, as well as leaf fineness. Fresh green leavesare rich in isomeric flavan-3-ols (catechins), on averageaccounting for 30% of their mass, with epigallocatechingallate (EGCG) being the most common component.During fermentation, some catechins undergo oxidationand condensation to high molecular weight compounds(3–6% theaflavins and 12–18% thearubigins) responsiblefor the characteristic flavor and aroma of infusions [4, 5,9, 8, 11, 12].Our study is an attempt to estimate the effect ofinfusions brewing time and storage on the content ofbioactive compounds (polyphenols and flavonoids) andantioxidant properties of 45 loose-leaf and bagged teasavailable on the Polish market.STUDY OBJECTS AND METHODSUsing the FRAP and DPPH methods, we comparedthe total content of polyphenols and flavonoids, as wellas the antioxidant properties of infusions made fromseveral types of loose-leaf (L) and bagged (E) teasavailable on the Polish market. Additionally, we assessedthe effects of the brewing time and storage of infusionson the total content of polyphenols and antioxidantproperties.The research material consisted of 45 teasproduced commercially by leading manufacturersResearch Article DOI: http://doi.org/10.21603/2308-4057-2020-1-91-97Open Access Available online at http://jfrm.ru/en/Changes of antioxidant activityand active compounds content in selected teasBarbara Kolodziej* , Danuta Sugier, Katarzyna LuchowskaUniversity of Life Sciences, Lublin, Poland* e-mail: barbara.kolodziej@up.lublin.plReceived September 05, 2019; Accepted in revised form January 13, 2020; Published February 25, 2020Abstract: Our study tested 45 tea infusions classified into five groups (white, green, red, black, and other teas) for the content of totalpolyphenols and flavonoids, as well as antioxidant properties, by the FRAP and DPPH methods. We examined these parameters afterprolongation of the brewing time from 10 to 30 min and overnight storage. The results showed that the capacity of the teas to bindfree radicals was differentiated and the amount of anti-oxidant compounds depended on their nature. In terms of antioxidant activityand total polyphenol content, the tested tea types were ranked in the following order: white > green > black > red > other teas (yerbamate > rooibos). Our experiment demonstrated a positive correlation between the polyphenol content and antioxidant activity of theanalyzed teas. Also, the DPPH antiradical efficiency was comparable to their ability to reduce ferric ions. The extended brewing timehad a significant effect on the antioxidant activity of the infusions and the polyphenolic compounds analyzed therein. In contrast,storage of the infusions for 24 h at room temperature changed their antioxidant activity and affected the total polyphenol content.Keywords: Tea infusion, FRAP, DPPH, polyphenols, flavonoids, brewing timePlease cite this article in press as: Kolodziej B, Sugier D, Luchowska K. Changes of antioxidant activity and active compoundscontent in selected teas. Foods and Raw Materials. 2020;8(1):91–97. DOI: http://doi.org/10.21603/2308-4057-2020-1-91-97.Copyright © 2020, Kolodziej et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 InternationalLicense (http://creativecommons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix,transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license.Foods and Raw Materials, 2020, vol. 8, no. 1E-ISSN 2310-9599ISSN 2308-405792Kolodziej B. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 91–97for the Polish market (Bastek Coffee & Tea, Mokate,Unilever Polska, Teekanne Polska, Roger Sp. z o.o.,Amber Spark, William’s Nature Products, Bio-activeSp. z o.o., Herbapol-Lublin S. A., Posti S.A., Himalaje– Najlepsze herbaty, Tata Global Beverages PolskaSp. z o.o.) and purchased in retail stores. In particular,we experimentally tested 5 white teas (W), 15 green teas(G), 5 red teas (R), 15 black teas (B), and 5 other teas,rooibos and yerba mate (Ro, YM). The names of theteas were assigned digital (chosen randomly in the fivegroups mentioned above) and letter designations.Methodology of analyses. One gram of teawas mixed with 100 mL of boiling distilled water,covered, and brewed for 10 min. The extracts werefiltered through a medium-sized filter. The infusionswere assayed for the total polyphenol content(o-dihydroxyphenols expressed as an equivalent ofcaffeic acid) using the spectrophotometric method ofSingleton and Rossi and the flavonoid content (expressedas an equivalent of quercetin) according to PolishPharmacopoeia VIII [13, 14].Furthermore, we determined the antioxidant activityof tea by using the FRAP method of Benzie and Strain(the capacity of reducing 1 mole of Fe (III) to Fe (II)expressed as μmoles of antioxidant compounds in 1 g ofraw material) and the modified DPPH Brand-Williamset al. method using a free radical of 1,1-diphenyl-2-picrylhydrazyl [15, 16]. The results were presented as %of free radical scavenging.Brewing time and freshness effects on antioxidantactivity and polyphenols. The samples under analysiswere brewed for 10 and 30 min and stored at roomtemperature for 24 h. Next, we assessed their antioxidantactivity using the FRAP method and determined thetotal polyphenol content. All assays for each samplewere performed in triplicate.Statistical analysis. All the data were subjected tovariance analysis. The significance of the differencesbetween mean values were verified with Tukey’s test(n = 3) at a significance level of 95%. Statistica 9.0(StatSoft) program was employed for the calculations.Additionally, we used Excel to calculate the coefficientsof simple correlations between the phytochemicalfeatures of the infusions and their antioxidant properties.RESULTS AND DISCUSSIONThe analyzed samples of teas available on the Polishmarket differed significantly in both the total polyphenoland flavonoid contents and their antioxidant propertiesevaluated after 10 min brewing (Table 1).As we can see, the content of flavonoids in theinfusions assayed with the methodology provided inFP VIII ranged from 0.06% for sample 12 BL (loose-leafblack tea) to 0.53% for sample 26GL (loose-leaf greentea) [14]. In general, the lowest values of the flavonoidcontent were found for red teas (0.17–0.19%) and rooibos(0.09–0.2%), whereas the average value in the otherTable 1 Polyphenols content, flavonoids content, FRAPand DPPH antioxidant activity of tea after 10 min of brewingSamplenumberPolyphenolscontent(caffeic acidequivalentmg g–1 dryweight)FRAPantioxidantactivity(equivalentμmol FeSO4g dm–1)DPPHantioxdantactivity(%scavengingfor 1gdry matter)Flavonoidscontent, % gdry matter-1(calculatedasquercetin)1 BL 39.46 880.96 47.96 0.252 BL 83.40 982.64 91.76 0.473 BE 73.80 941.42 83.05 0.414 BL 71.40 930.43 68.63 0.425 BL 37.17 590.45 44.54 0.236 BL 81.08 578.28 66.53 0.497 BL 65.52 788.70 65.23 0.258 BL 57.56 645.41 60.49 0.289 BE 64.64 685.45 55.09 0.3610 BE 75.72 515.12 3.76 0.0811 BL 71.36 505.96 55.01 0.2012 BL 32.16 461.53 72.54 0.0613 BE 97.02 1035.66 57.15 0.3914 BL 103.53 1317.66 66.01 0.4415 BL 83.64 1148.91 53.39 0.21Mean for B 69.17 800.57 59.41 0.3016 GL 61.41 874.29 60.78 0.3117 GL 121.50 1304.95 76.05 0.3818 GE 114.32 1337.54 69.94 0.4319 GL 78.69 1167.55 67.70 0.4020 GE 85.60 1183.65 76.71 0.3521 GE 107.03 899.82 37.38 0.2422 GL 96.55 748.12 47.84 0.1623 GL 86.67 379.59 24.35 0.3024 GE 119.98 1033.55 30.12 0.1425 GL 67.16 657.03 74.30 0.3826 GL 126.35 2257.19 93.29 0.5327 GE 94.55 1451.43 81.27 0.3428 GL 126.04 1251.54 43.95 0.3729 GL 114.23 1993.17 85.20 0.4630 GL 107.69 1944.46 89.89 0.25Mean for G 100.52 1232.26 63.92 0.3431 WE 105.69 1388.97 79.16 0.3532 WE 105.32 1300.64 70.92 0.4033 WL 87.97 1311.89 64.42 0.2334 WL 70.84 1400.81 61.26 0.1935 WE 116.54 1630.40 81.27 0.36Mean for W 97.27 1406.54 71.40 0.3036 RE 38.99 676.42 52.24 0.1737 RE 61.99 606.53 25.77 0.1938 RL 42.85 707.69 25.34 0.1839 RL 45.21 534.90 20.97 0.1840 RL 46.29 622.39 29.08 0.18Mean for R 47.07 629.59 30.68 0.1841 RoE 45.81 723.54 54.88 0.1442 RoE 29.06 603.01 29.62 0.0943 YML 60.95 997.95 76.71 0.2744 RoL 41.59 535.05 20.38 0.2045 YML 75.19 895.75 46.15 0.26Mean for RoY 50.52 751.06 45.55 0.19LSD0.05 ** ** ** **B – black tea; G – green tea; W – white tea; R – red tea; Ro – Rooibos tea;YM – Yerba Mate, L – loose-leaf tea; E – bagged tea***, **, * – significant at P ≤ 0.001, 0.01 or 0.0593Kolodziej B. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 91–97types of tea was about 0.3%. The flavonoid content inthe analyzed teas highly correlated with their antioxidantactivity, determined with the FRAP and DPPH methods(r2 = 0.548–0.666), and with the polyphenol content(r2 = 0.582). These results were in agreement with thosereported by Castiglioni et al., as well as Fernando andSoysa [17, 18].The total polyphenol content determined with theFolin-Ciocalteu method in the 45 analyzed tea infusionsranged from 29.1 (sample 42 RoE – loose-leaf rooibostea) to 126.4 mg·mL–1 (sample 26 GL – loose-leaf greentea), expressed as an equivalent of caffeic acid (Table 1,Fig. 1). The values were comparable with thosereported by Hilal and Engelhardt [19]. The highestcontent of polyphenols was found in the green teas(average 100.5 mg·mL–1), just as in the experimentsdescribed by McAlpine and Ward, Kiran and Kumar,as well as Shannon et al. [20–22]. The white teas werecharacterized by a slightly lower (mean 97.3 mg·mL–1)content of the active compounds.On average, the black teas contained 69.2 mg·mL–1of polyphenols, whereas the red tea as well as rooibosand yerba mate exhibited mean values of 47.1 and50.5 mg·mL–1, respectively. Similar results werereported by a number of researchers [7, 9, 21, 22].However, Plust et al., as well as Hilal and Engelhardt,found higher contents thereof in white teas and lowercontents in green teas and, especially, in black teas[3, 19]. In our experiment, higher total contents ofpolyphenols and flavonoids in green tea, comparedto white tea, might be due to slight oxidation of white(nonfermented) tea polyphenols during production.In fact, white teas do not undergo the inactivation ofenzymes before withering, so enzymes remain activeand white tea polyphenols are oxidized slowly [12].The antioxidant activity (assessed with FRAP andDPPH) and the polyphenol content demonstrated asignificant correlation (r2 = 0.435–0.732) and a considerablediversity of the results. This correlation betweenthe results of the three tests confirmed the validity of theprocedure we used for analysis. However, Almajano et al.found no linear correlation between the antiradicalactivity of the analyzed infusions and the content ofpolyphenolic compounds [9]. They suggested thatantiradical performance was influenced not only bythe content of polyphenols but also by their qualityand presence of other compounds that might enter theinfusions during extraction.A slightly different relationship was discoveredby Rusaczonek et al. and Castiglioni et al., i.e. a linearcorrelation between the total polyphenol content,flavonoids content, and antioxidant properties measuredwith ABST [7, 17]. Similar results were reported byPlust et al., Molan et al. and Aldiab, who used theFRAP method [3, 11, 23]. We should emphasize that theavailable literature describes a variety of methods fordetermination of antioxidant properties and polyphenoliccontent of tea infusions. Also, the authors employdifferent methods of extraction (temperature, time,solvent) while preparing solutions for analyses andexpress their results in different ways. Therefore, theresults are sometimes hardly comparable [1, 9, 11].The antioxidant activity of the teas measuredwith the FRAP method was in the range of 379.6–2257.2 μmol g d.w.–1 The highest antioxidant activity wasexhibited by the white and green tea samples, while thelowest activity was found for the red teas (over twice aslow). A similar trend was observed by Atalay and Ergeas well as Shannon et al. [12, 22].On average, the black teas had 35% weakerantioxidant properties than the green teas and a 43%lower Fe ion reduction ability than the white teas. Theseresults were in line with the findings of Aldiab [23].The antioxidant activity of this group of teas exhibiteda wide range of 461.5–1317.7 μmol g d.w.–1, whichindicated high variation of tea on the domestic market.Figure 1 Changes in polyphenol content (caffeic acid equivalent mg·g–1 dry weight)0204060801001201401601BL2BL3BE4BL5BL6BL7BL8BL9BE9BE10BL11BL13BE14BL15BL16GL17GL18GE19GL20GE21GE22GL23GL24GE25GL26GL27GE28GL29GL30GL31WE32WE33WL34WL35WE36RE37RE38RL39RL40RL41RoE42RoL43YML44RoL45YMLcaffeic acid equivalent mg g–1 dry weightpolyphenols content after 10 min of brewing polyphenols content after 30 min of brewingpolyphenols content after 24 h of infusion storing050010001500200025001BL2BL3BE4BL5BL6BL7BL8BL9BE9BE10BL11BL13BE14BL15BL16GL17GL18GE19GL20GE21GE22GL23GL24GE25GL26GL27GE28GL29GL30GL31WE32WE33WL34WL35WE36RE37RE38RL39RL40RL41RoE42RoL43YML44RoL45YMLequivalent μmol FeSO4 g dm–1FRAP after 10 min of brewing FRAP after 30 min of brewing FRAP after 24 h of infusion storingС94Kolodziej B. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 91–97These teas had slightly weaker antioxidant propertiesthan green teas due to the oxidation of catechinderivatives during processing and the presence of lessactive theaflavins and thearubigins in the infusions [12].The weaker antioxidant properties and a lowerpolyphenol content in these tea types were confirmed byother authors [12, 19]. Noteworthily, the loose-leaf whiteand red teas were characterized by lower activity thanthe bagged teas, while Plust et al. reported an oppositetrend for other tea types [3].Generally, the analyzed red teas had a significantlylower content of polyphenols and exhibited weakerantioxidant activity. This result was probably due to thedifferences in the manufacturing process, which involvesadditional drying of tea leaves before they are twisted,leading to slight fermentation of tea. Additional dryingmay result in an increased loss of active substances.Incomplete fermentation causes polymerization ofsimple polyphenols, as in black teas, but it does not lastlong. Another difference is the absence of heat treatmentfor black tea, which may induce differences in thecomposition of the pu-erh type teas.DPPH is a stable free radical that antioxidants canreact with, providing it with electrons or hydrogenatoms. As presented in Tables 1 and 2, the value ofantioxidant activity determined with the DPPH methodwas closely related to the results obtained using theFRAP method (r2 = 0.668).Concurrently, there were substantial differencesin the antioxidant activity of the analyzed extracts(from 3.8 to 93.3% radical scavenging). Just as in thestudy of McAlpine and Ward, the lowest DPPH radicalscavenging percentage was found for red tea (20.9–52.2%) and rooibos (20.4–54.9%), while the highestvalues were reported for white (61.3–81.3%) andgreen teas (24.4–93.3%) [21]. Similarly, Shannon et al.confirmed a higher DPPH radical scavenging capacity ofgreen tea, followed by black tea [20].The higher antioxidant activity of green teadetermined by both methods can be attributed to anepigallocatechin gallate content, showing a greater freeradical scavenging capacity than the other catechins [12].Our study found that the more processed the tea was,the lower its antioxidant capacity. Similar results werereported by Kiran and Kumar, as well as Cleverdon et al.[21, 24]. However, they did not agree with the findingsof Fik and Zawiślak, possibly due to the application ofa different solvent during preparation of infusions anddifferences in the geographical regions of tea cultivation,harvesting periods, or storage conditions [8].The most considerable differences between theantioxidant activities of the analyzed extracts wereobserved for the black teas. The loose-leaf typesexhibited higher activity than the bagged teas (Table 1).Additionally, just as in Cleverdon et al., true teas hadat least a two-fold greater polyphenol content than theherbal varieties [24]. The weaker free radical scavengingcapacity of rooibos tea (originating from Aspalathuslinearis L.) may result from its chemical composition:unlike Camellia sinensis L., it does not contain catechinsbut aspalathin, isoorientin, orientin, and rutin [24, 25].Similarly, yerba mate (produced from Ilexparaguariensis L.) does not contain catechins butsubstantial amounts of chlorogenic acid [26]. Wefound that the antioxidant activity of yerba mate wassubstantially lower than that reported by Boji et al. [26].However, as emphasized by Komes et al., yerba matecan exhibit low antioxidant activity compared to whiteand green teas [27].It seems that the differences between the polyphenolprofiles of “true” and herbal or rooibos teas could bethe direct cause of the differences in their antioxidantcapacity found in our study. We should take into accountthat the differences observed in these studies can berelated to different sample preparation methodologiesand use of different brewing times and tea-to-waterratios. What is more, the comparison of results issometimes difficult due to the lack of uniformity in theproperties of green tea, manufacturing and brewingconditions. Leaf age and size, harvesting season, andmanufacturing conditions are all important factors thatcan affect the results [4].Thus, according to our study, the teas tested with theFRAP and DPPH methods exhibited antioxidant activityin the following order: white teas > green > black > red> other teas (yerba mate > rooibos).In all the infusions, the total polyphenol contentincreased (from 6.9% in red teas to 19.7% in blackteas) with the infusion time, with higher values notedfor bagged teas (Fig. 1). These findings are in line withother studies conducted on different brands of looselypacked and bagged teas. In particular, Armoskaite et al.found that longer periods of extraction of green tea(30 min) led to higher quantities of phenolic compounds[2]. Nikniaz et al. reported similar results for blackteas [10]. However, storing infusions for 24 h at roomtemperature had a varied effect on the content of theseactive substances. Increased polyphenol contents weredetected in rooibos, yerba mate, red and white teas.In our study, we found black and green tea sampleswith increased polyphenol contents (1 BL, 2 BL, 4 BL,5 BL, 7 BL, 8 BL, 12 BL, 13 BE, 14 BL, 15 BL andTable 2 Single correlation coefficients between chosenfeatures of teasFRAP 10 DPPH 10 FV 10PL 10 0.732*** 0.435** 0.582***FRAP 10 0.668*** 0.548***DPPH 10 0.666***PL 10 – polyphenols content after 10 min of brewing; FRAP 10 –FRAP antioxidant activity after 10 min of brewing; DPPH 10 – DPPHantioxidant activity after 10 min of brewing; FV 10 – flavonoidscontent after 10 min of brewing***, **, * – significant at P ≤ 0.001, 0.01 or 0.0595Kolodziej B. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 91–9716 GL, 19 GL, 20 GE, 27 GE, 28 GL), while in the othergroups, the content declined from 4 to 42%. Similarly,increased quercetin, flavonoids and total polyphenolcontents were recorded along with prolonged teabrewing in Molan et al., Castiglioni et al., Fernandoand Soysa, as well as Palanivel et al. [11, 17, 18,28]. According to Armoskaite et al., flavonoids (andcatechins, their fraction) are basic phenolic compoundsin green tea responsible for antioxidant activity [2].What is more, Saklar et al. reported that greentea catechins may be converted from epi forms tonon-epi forms due to epimerization reactions at longbrewing times [4]. Jin et al. proved that concentrationsof epicatechins peaked at 10 min, after which theydecreased drastically, while levels of non-epicatechinsincreased steadily for 5 h [5]. However, the antioxidantactivity was more dependent on brewing temperaturethan brewing time. It is worth emphasizing that teacatechins can act as antioxidants by donating hydrogenatoms or by chelating metals, but epicatechins areknown to be stronger than their corresponding non-epiisomers [9].Further, we assessed the Fe ion reduction ability ofthe infusions brewed for 10 and 30 min (Fig. 2).In the 45 teas analyzed, both a decline and an increasein antioxidant activity (particularly in red teas andyerba mate) were detected over the prolonged brewingtime. These results were in line with Nikniaz et al.who reported higher values for bagged teas [10]. Themost substantial differences were found among the blackteas. In particular, infusions 1 BL, 2 BL, 3 BE, 4 BL,and 5 BL exhibited a decreased Fe ion reduction abilityin a range of 4.2–26.6%, whereas the other infusionswere characterized by an increased ferric reducingantioxidant power FRAP (from 1.4 to 44.5%). Increasedantioxidant activity was detected in the infusions of theother tea types (except for green tea samples 23 GL,25 GL, and 26 GL).Previously published studies reported that theantioxidant capacity and total polyphenols in teaextracts correlated with the extraction time [10, 11, 19].It is worth underlining that according to Armoskaiteet al. and Pastoriza et al., the time of extraction andantioxidant activity may not always be in directproportion: longer extraction time results in lowerantioxidant activity in some green teas and higher inothers [2, 6].In our study, the FRAP antioxidant activity of thetea infusions stored for 24 h at room temperature variedin a non-uniform manner and the statistical analysisdid not confirm the significance of the differences. Themagnitude of a decrease or an increase in antioxidantactivity was not correlated with the tea type: both werenoted in the groups of the same tea types. On average,the black teas exhibited a 14.8% increase in the Fe ionreduction ability. However, some infusions from thisgroup were characterized by a decreased Fe ion reductionability (samples 10 BE, 13 BE, 14 BL, and 15 BL).In the other tea groups, we noted a decline inantioxidant activity, particularly in the red and greenteas. At the same time, each group comprised somesamples with a Fe ion chelating ability that increasedthroughout storage (samples 16 GL, 17 GL, 18 GE,19 GL, 20 GE, 23GL of the green teas, samples 31 WLand 32 WL of the white teas, sample 36 RE of the redteas, and samples 41 RoE, 42 RoE, and 43 YML of theteas other than Camellia sinensis). According to Komeset al., this variation might be due to a great abundanceand variability of tea constituents that participate invarious reactions during storage in the presence ofoxygen, such as polymerization, or even degradationof some tea compounds [30]. Therefore, as indicatedby Jayabalan et al., the qualitative and quantitativecomposition of tea infusions undergoes change over timewith significant differences detectable only after severaldays of brewing [29].Figure 2 Changes in antioxidant activity of FRAP (Equivalent μmol FeSO4 g·dm–1) in the tested teas0204060801001201401601BL2BL3BE4BL5BL6BL7BL8BL9BE9BE10BL11BL13BE14BL15BL16GL17GL18GE19GL20GE21GE22GL23GL24GE25GL26GL27GE28GL29GL30GL31WE32WE33WL34WL35WE36RE37RE38RL39RL40RL41RoE42RoL43YML44RoL45YMLcaffeic acid equivalent mg g–1 dry weightpolyphenols content after 10 min of brewing polyphenols content after 30 min of brewingpolyphenols content after 24 h of infusion storing050010001500200025001BL2BL3BE4BL5BL6BL7BL8BL9BE9BE10BL11BL13BE14BL15BL16GL17GL18GE19GL20GE21GE22GL23GL24GE25GL26GL27GE28GL29GL30GL31WE32WE33WL34WL35WE36RE37RE38RL39RL40RL41RoE42RoL43YML44RoL45YMLequivalent μmol FeSO4 g dm–1FRAP after 10 min of brewing FRAP after 30 min of brewing FRAP after 24 h of infusion storingE·96Kolodziej B. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 91–97CONCLUSIONOur experiment demonstrated a considerablediversity of teas available on the Polish market,contributing to the variability of active compounds andantioxidant activity of tea infusions. The teas underanalysis were characterized by varied free radicalscavenging abilities, and the amount of antioxidantsdepended primarily on the type of tea. The nonfermentedteas (white and green) exhibited the highestantioxidant activity (measured with the FRAPand DPPH methods) and total polyphenol content.Weaker antioxidant properties and a lower content ofpolyphenols were detected in the black teas. The lowestvalues were found in rooibos and yerba mate, as well asin the red teas.Our study showed a positive correlation between thepolyphenol content and antioxidant activity. In addition,the DPPH antiradical performance of the examinedextracts was comparable to their Fe ion chelatingability. The prolonged brewing time had a significanteffect on the antioxidant activity of the infusions andpolyphenolic compounds contained therein, which wasnot a linear correlation. Similarly, storage for 24 h atroom temperature induced changes in the antioxidantactivity of the infusions and altered their totalpolyphenol content.The information contained in our study can beuseful for tea consumers in their choice of tea, as wellas preparation and storage methods that ensure thebest pro-health properties. In addition, the substantialdifferences in the content of active compounds andantioxidant properties of the examined tea typesmanufactured by various producers suggest a needfor establishing appropriate technological parameters,quality requirements, and systematic control of theircomposition and properties. Given the fact that thereare no standards for teas other than black in Europe, thequality of all types of tea traded on the Polish marketshould be standardized to ensure similar quality ofproducts and fair market competition.CONTRIBUTIONThe authors were equally involved in writing themanuscript and are equally responsible for plagiarism.CONFLICT OF INTERESTThe authors declare that there is no conflict ofinterest.