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Citation: Najman, K.; Rajewski, R.;
Sadowska, A.; Hallmann, E.; Buczak,
K. Changes in the Physicochemical
and Bioactive Properties of Yerba
Mate Depending on the Brewing
Conditions. Molecules 2024,29, 2590.
https://doi.org/10.3390/
molecules29112590
Academic Editors: Marica T.
Engström and Maarit Karonen
Received: 8 May 2024
Revised: 28 May 2024
Accepted: 30 May 2024
Published: 31 May 2024
Copyright: © 2024 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/).
molecules
Article
Changes in the Physicochemical and Bioactive Properties of
Yerba Mate Depending on the Brewing Conditions
Katarzyna Najman 1, * , Rafał Rajewski 1, Anna Sadowska 1, Ewelina Hallmann 1,2 and Krzysztof Buczak 3
1Department of Functional and Organic Food, Institute of Human Nutrition Sciences, Warsaw University of
Life Sciences, Nowoursynowska 159c, 02-776 Warsaw, Poland; anna_sadowska@sggw.edu.pl (A.S.)
2Bioeconomy Research Institute, Agriculture Academy, Vytautas Magnus University, Donelaicio 58,
44248 Kaunas, Lithuania
3Department of Surgery, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life
Science, Pl. Grunwadzki 51, 50-366 Wroclaw, Poland
*Correspondence: katarzyna_najman@sggw.edu.pl
Abstract: 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 (
∆
E) 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
µ
g/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
µ
M 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
µ
g/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
µ
M 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.
Keywords: yerba mate; Paraguayan holly (Ilex paraguariensis A. St.-Hil.); single and double brewing;
color parameters L*a*b*; tannins; caffeine; carotenoids; polyphenols; antioxidant activity
1. Introduction
Yerba Mate is a drink made from the dried and fragmented leaves and twigs of
Paraguayan holly (Ilex paraguariensis A. St.-Hil.), a plant belonging to the holly family
(Aquifoliaceae), the holly genus (Ilex), which includes over 450 species, such as Ilex brevicuspis,
Ilex dumosa,Ilex integerrima,Ilex affinis, occurring in South America [1–3].
Yerba Mate is the national drink of Brazil, Argentina, Uruguay, and Paraguay [
3
,
4
],
and its consumption is deeply rooted in the tradition of these countries, referring to the
old customs of the Guarani Indians, who treated this drink as a symbol of reconciliation
and friendship [
1
,
2
,
5
]. Yerba Mate is closely related to the culture and customs of South
Molecules 2024,29, 2590. https://doi.org/10.3390/molecules29112590 https://www.mdpi.com/journal/molecules
Molecules 2024,29, 2590 2 of 27
American countries [
2
,
4
], but in recent years its consumption outside the home continent,
mainly in Europe [4,6], in particular Poland [7], has been rapidly increasing.
The beneficial effects of Yerba Mate consumption on health were already appreciated
by its discoverers [
2
]. Nowadays, the literature describes Yerba Mate as a valuable source of
biologically active substances supporting the body functioning and playing an important
role in the prevention as well as in the treatment of various diseases, including lifestyle
diseases [
8
]. The pro-health properties of Yerba Mate, widely described in the literature may
contribute to the prevention of diseases such as obesity [
8
], insulin resistance, or diabetes [
9
],
e.g., by reducing body weight and the amount of food consumed, increasing the rate of
gastric emptying, lowering insulin level, and improving glucose and lipid metabolism
(closely related to adipose tissue), as well as increasing the concentration of glucagon-like
peptide 1 (GLP-1) and leptin, factors responsible for the feeling of satiety [
8
,
9
]. Many
studies confirm also the important role of Yerba Mate in the prevention of cardiovascular
diseases [
6
,
10
]. Yerba Mate may also have anti-mutagenic, anti-proliferative, cytotoxic, and
anti-cancer effects in relation to various cancers [
9
,
11
,
12
]. The beneficial effect of Yerba
Mate in the course of neurological and neurodegenerative diseases is also known [
13
]. The
flavones, caffeine, theobromine, and theophylline present in this plant and in its infusions
have a neuroprotective effect, improve mood, cognitive functions, concentration, and
stimulate and support mental work, as well as affecting the increase in the number of
synapses and extend the life of nerve cells [13,14].
Paraguayan holly (Ilex paraguariensis A. St.-Hil.) is a plant characterized by a high
content of bioactive ingredients such as purine and xanthine alkaloids, polyphenols, and
other antioxidants or tannins that have a positive effect on human health [4,8,9,15–19].
The content of purine alkaloids, mainly including caffeine, also present in coffee, tea or
cocoa [
13
], in Yerba Mate is from 41.82 to 82.4 mg of caffeine per 150 mL, which, in terms of
the content of this ingredient, puts it on par with green tea (from
11.83 to 51.57 mg/150 mL
)
or coffee (from 42.27 up to 120.89 mg/150 mL) [14].
Yerba Mate has strong antioxidant properties, resulting from a high content of carotenoid
and phenolic components [
4
,
8
,
9
,
15
–
17
,
20
–
23
]. Common antioxidants in Yerba Mate are
phenolic acids such as chlorogenic, caffeic, feluric, and gallic acids [
24
]. Other phenolic
components with antioxidant activity are flavonoids, among which rutin, quercetin 3-
rhamnoside and 3-glucoside, kaempferol 3-rhamnoside and 3-glucoside, and luteolin
diglycoside are the most common in Yerba Mate [25–27].
A very rarely described group of phenolic components in Yerba Mate are tannins [
18
,
19
].
These include compounds with a molecular weight from 500 to even 3000 Da and a large
number of functional groups, thanks to which they bind to proteins, polysaccharides [
28
,
29
],
metal ions, or alkaloids, forming water-insoluble complexes [30,31].
Many beneficial properties are attributed to tannins, including astringent and alkaloid-
binding properties (helpful in the treatment of diarrhea and food poisoning) [
29
,
32
,
33
] or
antifungal and antiviral properties (thanks to binding of the microorganisms’ cell wall
polysaccharides and proteins) [
32
–
34
]. The ability to complex metals inhibits, e.g., the
activity of hyaluronidase, lipoxygenase, protein kinase C, or ACE (angiotensin converting
enzyme), which is why tannins also have anti-inflammatory properties [
35
]. The antidia-
betic properties of tannins are known from their ability to slow down glucose absorption
and lower blood sugar levels [
36
]. Tannins shape the appropriate astringent, sour, or bitter
taste characteristics of wine or tea [37].
Due to the richness of ingredients and their high content and biological activity, Yerba
Mate is increasingly used as an ingredient of functional food, which is confirmed by the
appearance of products with Yerba Mate additions on the market, such as pasta, bakery
and pastry products, ice cream, smoothies and shakes, lemonades, dessert coffees, alcoholic
cocktails, and others [
38
]. Due to the high caffeine content, it is also used in the production
of energy drinks and various types of cold drinks [
14
]; however, both in South America
and Europe, Yerba Mate is most often consumed as a traditional brew [2,4,5,16].
Molecules 2024,29, 2590 3 of 27
The optimum brewing temperature for Yerba Mate is 65–80
◦
C, while, according to
the traditional brewing process, 75% of the vessel should be occupied by dried material, in
which case the brew has a heavy, bitter, and astringent taste and a dark, green, sometimes
green-brown color [
4
,
5
]. Also, the mixtures of Yerba Mate products on the market differ in
both the type and composition of the dried material, including the proportions of dried
leaves to twigs and sticks [
1
,
39
,
40
]. Generally, there are two basic types of Yerba Mate,
i.e., “elaborada” (or “elaborada con palo”) containing up to 30% twigs and sticks, and
“despalada” (or “despalada sin palo”), containing up to 10% of these elements [
40
,
41
]. In
practice, commercial products differ in the content of leaves, twigs, sticks, or dust; they
may also contain the addition of dried herbs, fruits, or flowers [
2
,
40
], which makes Yerba
Mate market products extremely diverse, both in terms of organoleptic and bioactive
characteristics [26,40].
The contents of bioactive ingredients, as well as the biological activity and health-
promoting properties of Yerba Mate, depend on many factors, including the origin of the
Paraguayan holly [
23
], plant growth conditions, i.e., substrate, soil type, climate, degree
of insolation or cultivation system [
39
,
42
], plant variety and morphotype [
17
,
43
], different
parts of the plant [
44
], or leaf age [
20
,
45
]. Differences in the content of ingredients and
bioactive properties also result from the composition and degree of fragmentation of
commercially available mixtures [
6
,
25
–
27
,
44
,
46
,
47
], as well as the production technology
and degree of processing of the Yerba Mate [
3
,
16
,
20
,
21
,
42
,
45
,
46
,
48
]. The key factors for the
organoleptic and bioactive properties of Yerba Mate infusions are also the brewing methods
and conditions, including temperature, time, and the number of infusions [16,45,48,49].
Similarly to tea, Yerba Mate is consumed in the form of a warm drink, an infusion
of dried plant leaves, but these drinks are not the same. Tea is an infusion of Chinese tea
leaves (Camellia sinensis), a plant originating in Asia, while Yerba Mate is an infusion of
Paraguayan holly (Ilex paraguariensis), originating in South American countries [
50
]. In
addition, tea is usually brewed in boiling or slightly cooled water, while for Yerba Mate
brewing the water temperature is usually between 65
◦
C and 80
◦
C [
2
]. Most often, the
process of brewing Yerba Mate in optimal temperature conditions lasts from 5 to 10 min,
and, unlike tea, Yerba Mate is brewed many times, depending on consumer preferences [
16
].
From the consumer’s point of view, not only the color, aroma and taste are important,
but also the content of ingredients determining the bioactive properties of Yerba Mate
infusions [
51
–
53
]. While the health-promoting properties of Yerba Mate are well known
and described in the literature, there are no reports on the organoleptic and physicochemical
properties of infusions prepared in different conditions.
There is also a lack of data on changes in the content and bioactive compounds
profile in Yerba Mate infusions, such as tannins, caffeine, and the phenolic acid profile of
flavonoids and carotenoids, as well as total polyphenol content and antioxidant activity
depending on different brewing conditions. Therefore, this study examined the influence
of the temperature optimal for brewing Yerba Mate (i.e., 70
◦
C) and optimal for brewing
most teas (i.e., 100
◦
C) as well as the number of brewing times (single and double) of Yerba
Mate on the organoleptic characteristics (in particular color), physicochemical properties
(ph,
◦
Brix, osmolality), the content of bioactive ingredients, including tannins and caffeine,
the profile of phenolic acids, flavonoids, carotenoids, and the content of total polyphenols
and the antioxidant activity of the infusions obtained in this way.
2. Results and Discussion
2.1. Physicochemical Properties of Dried Yerba Mate and Its Different Infusions
The general appearance of dried Yerba Mate samples are shown in Figure 1. In the
organoleptic assessment, all the tested Yerba Mate samples were loose and dry, but they
differed in the degree of fragmentation and the structure of the mixture, resulting from the
share of leaves, twigs and dust. The highest degree of fragmentation was found in YM-A
(Figure 1a), with a small, but clearly visible, amount of fragmented twigs. This sample
was also characterized by the highest dust content. The YM-C sample (Figure 1c) was
Molecules 2024,29, 2590 4 of 27
characterized by a lower degree of decomposition of the mixture, a moderate content of
dust and an average content of visible fragments of twigs with a large predominance of
quite finely ground leaves. The sample with the lowest degree of fragmentation and the
smallest dustiness, with fragments of finely cut twigs and sticks clearly visible and present
in a relatively large amount in the mixture was the YM-B sample (Figure 1b).
Figure 1. General appearance of dried Yerba Mate samples: YM-A (a), YM-B (b), YM-C (c).
All dried Yerba Mate samples had a strong, sweet, grassy, fresh hay-like aroma, with
noticeable smoky notes. The most intense aroma was found in the YB-A sample, while the
least aromatic was in the Yerba Mate YM-B sample.
In the organoleptic evaluation, the dried samples were characterized by a similar,
green-brown, quite heterogeneous color, resulting from the varying degree of fragmentation
of the mixture, and thus from the varying proportion of fragments of brightly colored twigs
and sticks or dust. Samples with a greater share of twig fragments brightening of the
mixture, were optically brighter. The most optically homogeneous composition of the
mixture was distinguished by YM-A (with the highest degree of fragmentation), while YM-
B was characterized by the least uniform color and its shade. No lumps, solid impurities or
pests were found in any of the tested died samples. Foreign, non-specific aromas were also
imperceptible, which proved the correct conditions of transport and storage.
One of the most important attributes of the appearance of food products, strongly af-
fecting consumer acceptance, is color. Undesirable colors may induce the consumer to reject
such products [
54
,
55
]. This attribute is the basic selection criterion for tea consumers [
51
]. In
the case of Yerba Mate, color preferences depend on the country, with consumers in Brazil
preferring light green, while in Argentina, Paraguay and Uruguay light olive, obtained as a
result of the chlorophyll degradation during the Yerba Mate production [52].
From the point of view of the organoleptic assessment and the overall quality of
products, it is important to determine the color of dried Yerba Mate and the effect of various
brewing conditions of Yerba Mate on the color parameters of the infusions.
Table 1presents the basic physicochemical parameters, such as moisture content and
water activity (a
w
), as well as chromatic coordinates in the CIE LAB color space (L*a*b*) and
browning index (BI) of dried Yerba Mate samples.
Dried Yerba Mate products were characterized by low water activity (average
0.38
±
0.01) and low moisture content (average 5.50
±
0.36%). Considering that the optimal
a
w
for the development of most microorganisms is higher than 0.60 [
56
], low a
w
in the Yerba
Mate samples proved the high durability and microbiological safety of these products, as
well as the correct production, transport or storage process [
19
]. In the available literature,
there is little data on water activity and moisture content in dried Yerba Mate, however,
Frizon and Nisgoski (2020) [
19
] showed a similar moisture content in Yerba Mate products,
ranging from 5.05
±
0.8% (organic) to 5.21
±
0.4% and even 5.94
±
0.3% (conventional).
These authors showed that at various stages of Yerba Mate production, the moisture content
in green leaves from organic (65.27
±
2.0%) and conventional (
60.62 ±1.7%
) cultivation
was reduced (by approx. 92%), also determining the color changes in dried products [19].
Molecules 2024,29, 2590 5 of 27
Table 1. Moisture content (%), water activity (a
w
), chromatic coordinates in the CIE LAB color space
(L*a*b*) and browning index (BI) of dried Yerba Mate samples.
Sample Moisture
(%)
Water Activity
(aw)
L*
(Lightness)
a*
(Greenness)
b*
(Yellowness)
BI
(Browning Index)
YM-A 5.58 ±0.04 b0.38 ±0.00 b48.78 ±5.04 b−0.58 ±0.17 c34.87 ±3.48 b110.93 ±6.10 b
YM-B 5.86 ±0.04 c0.37 ±0.00 a37.63 ±1.63 a−1.45 ±0.14 b27.95 ±1.30 a115.64 ±2.12 b
YM-C 5.05 ±0.02 a0.38 ±0.00 b74.00 ±3.31 c−2.25 ±0.38 a32.52 ±1.84 b52.91 ±2.28 a
Mean values
±
standard deviation with different letters (
a–c
) in the same column differ significantly (Duncan’s
test, p ≤0.05).
As the research shows, the dried Yerba Mate samples (Table 1) differed (p
≤
0.05) in
color L*a*b* parameters. The L* parameter, defining the lightness, ranged from 37.63
±
1.63
to 74.00 ±3.31, with the darkest YM-B, the brighter YM-A, and YM-C the brightest.
All dried Yerba Mate samples showed negative values of the a* parameter, which
meant that they were characterized by a color shift towards shades of green, with the
highest intensity of this color noted in the case of YM-C (
−
2.25
±
0.38), significantly
(p≤0.05) lower for YM-B and YM-A.
The tested droughts were also characterized by clear shades of yellow color, reaching
positive values of the b* parameter (defining yellow tones), which on average for all
analyzed Yerba Mate samples amounted to 31.78
±
3.71. The highest values for this
parameter were found in samples YM-A and YM-C (average 33.69
±
2.93), which meant
that their color was mostly shifted towards yellow shades, unlike YM-B, for which the
value of parameter b* were significantly (p≤0.05) the lowest (27.95 ±1.30).
In the literature, there are few studies on the color parameters of Yerba Mate. Frizon
and Nisgoski (2020) [
19
] showed that the color of fresh holly leaves varied depending on
the growing conditions and changed during the different steps of Yerba Mate production.
Green leaves were characterized by negative (
−
a) values in the range from
−
8.50
±
0.69 to
4.48
±
1.16, after bleaching (2–3 min burning at 500–600
◦
C) the values of the a* component
ranged from
−
7.96
±
0.66 to
−
6.04
±
1.31 (organic and conventional cultivation, respec-
tively). On the other hand, the drying and grinding processes gradually led to the loss
of green color, reaching values from
−
3.92
±
1.74 to 3.49
±
0.65, and after storage from
−
2.03
±
0.19 to 0.12
±
0.47 [
19
], which was close to the values in this study. A similar trend
was found by Schmalko and Alzamora (2001) [
47
], although their values for the coordinate
(−a) were much lower (from 9.13 in fresh to −5.46 in dried Yerba Mate leaves).
As a result of heat treatment, in addition to the loss of green color (
−
a*), the intensity of
yellow color (b*) and lightness (L*) also increase [
19
]. In the studies of Frizon and Nisgoski
(2020) [
19
], in the industrial Yerba Mate production, dried samples reached values for the
chromatic coordinate b* from 17.87
±
1.87 to 31.59
±
3.77, and therefore similar to those in
this study (Table 1), lower values for parameter b* (from 17 to 21) was found by Schmalko
and Alzamora (2001) [
47
]. These differences can be explained by age of leaves, varied
content of chlorophyll a and b in fresh leaves and the rate of degradation of these pigments
depending on the time and temperature of leaf drying [
19
,
47
], as well as the degree of
fragmentation and the rate of tissue dehydration during the Yerba Mate production [
47
].
Differences in color, especially in the brightness of dried Yerba Mate, also depend on the
growing conditions (conventional vs. organic), storage time, or moisture content [19].
According to the literature, higher moisture content is accompanied by a decrease
in the value of L* and b* color parameters [
19
], which was confirmed by the research
conducted in this study (Table 1). The YM-C with the significantly (p
≤
0.05) lowest
moisture content (5.05
±
0.02%) was characterized by the significantly highest value of the
L* parameter (74.00
±
3.31) and the lowest browning index (52.91
±
2.28), and therefore
the highest brightness. In turn, the YM-B sample, with significantly (p
≤
0.05) the highest
moisture content (5.86
±
0.04%), was characterized by the lowest value of the L* parameter
(
37.63 ±1.63
) and was the darkest, displaying the highest browning index (115.64
±
2.12).
Molecules 2024,29, 2590 6 of 27
Yerba Mate is usually consumed in the form of a warm drink, prepared at a temper-
ature of 65–80
◦
C [
2
], similarly to tea, but usually brewed in boiling or slightly cooled
water [
50
]. In addition, unlike tea, Yerba Mate is brewed many times (depending on
consumer preferences) [
16
]. Which is why, in this study, the effect of the temperature,
optimal for brewing Yerba Mate (70
◦
C) and optimal for brewing most teas (100
◦
C), and
brewing numbers (1-time and 2-times) on the organoleptic, physicochemical and bioactive
properties of Yerba Mate infusions obtained in this way were evaluated.
Figure 2shows the general appearance of filtered Yerba Mate infusions prepared at
70
◦
C and 100
◦
C after the first brewing, while Figure 3shows the infusions obtained after
the second brewing at both temperatures.
In the organoleptic evaluation, the infusions obtained as a result of the first brewing
(Figure 2) were characterized by an intense green-brown color, which they clearly lost
during the double brewing (Figure 3).
Figure 2. General appearance of filtered Yerba Mate infusions obtained as a result of single brewing
at 70
◦
C and 100
◦
C: YM-A-1-70 (a), YM-B-1-70 (b), YM-C-1-70 (c), YM-A-1-100 (d), YM-B-1-100 (e),
YM-C-1-100 (f).
Figure 3. General appearance of filtered Yerba Mate infusions obtained as a result of double brewing
at 70
◦
C and 100
◦
C: YM-A-2-70 (a), YM-B-2-70 (b), YM-C-2-70 (c), YM-A-2-100 (d), YM-B-2-100 (e),
YM-C-2-100 (f).
Yerba Mate infusions obtained after single brewing were characterized by an intense,
smoky aroma and noticeable woody notes. The taste of YM-A and YM-B infusions was from
the beginning expressive, intense, sour, slightly tart, with a hint of bitterness reminiscent of
the aftertaste of fresh walnut peel, while the intensity of the YM-A flavor faded quickly,
clearly softening in the second brewing. YM-B infusion retained its flavor much longer,
losing little on the second brewing, which made it a perfect Mate for multiple brews. On
the other hand, the YM-C infusion was initially quite smooth in taste, quickly becoming
creamy or even thick, with vegetable, sweet and sour and smoky notes.
After preparing the infusions, it was noticed that the samples differed in the intensity
of the bitter, sour and smoked taste, with the infusions prepared at a higher temperature
(100
◦
) being more bitter than those brewed at 70
◦
C. YM-A-1-100 infusion was characterized
by the most intense bitter taste.
Molecules 2024,29, 2590 7 of 27
All the infusions obtained during the second brewing, both at 70
◦
C and 100
◦
C,
became clearly softened, less intense, more delicate and watery in taste. The infusion that
retained its taste and aroma from the first brewing to the greatest extent was YM-C.
In the organoleptic evaluation, the infusions obtained as a result of double brewing
(Figure 3) were characterized by a clearly weaker color intensity and its much less color
differentiation, as well as lighter shades or greater clarity than infusions obtained during
single brewing (Figure 2). Therefore, in Yerba Mate infusions prepared at different tempera-
tures (70
◦
C and 100
◦
C), color parameters in the L*a*b* color space, various color functions,
i.e., browning index (IB) and total color difference (
∆
E) were evaluated, and the obtained
results are presented in Table 2(single brewing) and in Table 3(double brewing).
All infusions obtained as a result of double brewing (Table 3) were characterized
by much greater brightness (by almost 60%) than those brewed once (Table 2). The L*
parameter, was on average 36.46
±
4.46 and 57.55
±
1.65 (for double and single infusions,
respectively) with samples brewed once at a lower (70
◦
C) temperature being slightly
lighter (on average 38.13
±
5.06) than those brewed in higher (100
◦
C) temperature (average
34.78
±
3.22). In addition, the L* parameter in the case of infusions brewed twice showed
much less variability than in infusions brewed once.
Considering the single brewing (Table 2), the darkest shade was found in the YM-A-
1-100 infusion (30.60
±
0.20), while the YM-B-1-70 infusion was significantly (p
≤
0.05)
the brightest (43.80
±
1.70). The lowest L* value in infusions brewed twice (Table 3)
were recorded in YM-C-2-70 (55.05
±
0.25), higher (p
≤
0.05) in YM-A-2-100, YM-B-2-70,
YM-B-2-100 and YM-C-2-100, while the brightest was YM-A-2-70 infusion (60.00 ±0.20).
Comparing the number of Yerba Mate brews effect on the color parameters, the
greatest differences were found in the case of chromatic coordinate a*. Yerba Mate brewed
once (Table 2) showed positive (+a*) values (on average 13.57
±
2.31), and therefore a
predominance of red shades, while those brewed twice (Table 3) showed negative (
−
a*)
values, which means that they were dominated by shades of green (average
−
1.65
±
0.89).
Yerba Mate infusions with the highest (p
≤
0.05) red color saturation were YM-A-1-100
and YM-C-1-70 (average 15.56
±
0.28), followed by YM-B-1-100 and YM-C-1-100 (mean
14.43
±
0.62) and YM-A-1-70 (12.10
±
0.40). The lowest (p
≤
0.05) degree of saturation with
red color was characteristic of the YM-B-1-70 infusion (9.35
±
0.15), which was at the same
time the lightest among those brewed once.
Table 2. Chromatic coordinates in the CIE LAB (L*a*b*)color space, browning index (BI) and total
color difference (
∆
E) of Yerba Mate infusions obtained as a result of single brewing at 70
◦
C and
100 ◦C.
Sample L*
(Lightness)
a*
(Redness)
b*
(Yellowness)
BI
(Browning Index)∆E
YM-A-1-70 32.30 ±0.10 b12.10 ±0.40 b39.95 ±0.15 b360.26 ±0.31 e21.41 ±0.28 b
YM-B-1-70 43.80 ±1.70 e9.35 ±0.15 a45.10 ±0.60 e235.74 ±12.72 a21.22 ±0.90 ab
YM-C-1-70 38.30 ±0.40 d15.40 ±0.30 de 44.75 ±0.35 e316.68 ±2.24 d41.66 ±0.37 d
YM-A-1-100 30.60 ±0.20 a15.72 ±0.19 e34.05 ±0.25 a290.60 ±8.19 b24.43 ±0.26 c
YM-B-1-100 36.15 ±0.65 c14.68 ±0.63 cd 40.75 ±0.05 c293.85 ±10.22 bc 20.66 ±0.48 a
YM-C-1-100 37.60 ±0.30 d14.18 ±0.60 c43.45 ±0.25 d308.39 ±9.45 cd 41.41 ±0.44 d
Mean values
±
standard deviation with different letters (
a–e
) in the same column differ significantly (Duncan’s
test, p≤0.05).
In the case of double brewing (Table 3), all Yerba Mate infusions obtained negative a*
values, which means that they were characterized by a predominance of green (
−
a*) over red
(+a*) shades, and the highest share of green color was noted in YM-C-2-100 (
−
2.85
±
0.05),
lower in YM-B-2-70 and YM-A-2-70 infusions. The smallest color shift towards green shades
was found in YM-B-2-100 and YM-A-2-100 infusions (average −0.64 ±0.09).
Taking into account the chromatic coordinate b*, the instrumental color measurement
showed the smallest differences between Yerba Mate brewed once and twice. This parame-
Molecules 2024,29, 2590 8 of 27
ter for all infusions had positive values (+b*), meaning that they had more yellow (+b*) than
blue (
−
b*) shades, with a slightly larger color shift towards yellow in a double infusion
(average 44.25 ±4.00) than in a single one (average 41.34 ±3.90).
Table 3. Color parameters in the CIE LAB (L*a*b*)color space, browning index (BI) and total color
difference (∆E) of Yerba Mate infusions obtained as a result of double brewing at 70 ◦C and 100 ◦C.
Sample L*
(Lightness)
a*
(Redness)
b*
(Yellowness)
BI
(Browning Index)∆E
YM-A-2-70 60.00 ±0.20 c−1.88 ±0.13 c43.60 ±0.40 b112.06 ±0.93 b14.28 ±0.41 a
YM-B-2-70 57.30 ±1.60 b−2.55 ±0.15 b39.15 ±0.35 a100.32 ±5.72 a22.68 ±1,21 d
YM-C-2-70 55.05 ±0.25 a−1.38 ±0.13 d45.10 ±0.70 c138.62 ±2.57 c22.77 ±0.17 d
YM-A-2-100 57.15 ±0.35 b−0.58 ±0.08 e49.15 ±0.35 d152.87 ±3.65 d16.56 ±0.12 b
YM-B-2-100 57.65 ±0.85 b−0.70 ±0.05 e48.65 ±0.15 d147.45 ±3.07 d28.81 ±0.70 e
YM-C-2-100 58.15 ±0.65 b−2.85 ±0.05 a39.85 ±0.40 a100.23 ±0.21 a17.48 ±0.42 c
Mean values
±
standard deviation with different letters (
a–e
) in the same column differ significantly (Duncan’s
test, p≤0.05).
In the case of single-brewed infusions, higher saturation with yellow shades was noted
in samples brewed at a lower temperature (70
◦
C), for which b* value was 43.27
±
2.52, with
the highest (p
≤
0.05) values in YM-C-1-70 and YM-B-1-70 (mean 44.93
±
0.48). Yerba Mate
brewed once at 100
◦
C reached an average of 39.42
±
4.20 for this parameter, with the lowest
(p
≤
0.05) value for YM-A-1-100 (34.05
±
0.25). In the case of double brewing, the opposite
trend was found. When brewing at a higher temperature (100
◦
C), higher b* values were
obtained (average 45.88
±
4.54) than at a lower temperature (70
◦
C) (average 42.62
±
2.72).
The highest (p
≤
0.05) b* values were recorded in YM-A-2-100 and YM-B-2-100 (average
48.90 ±0.36
), and the lowest in YM-B-2-70 (39.15
±
0.35). The available literature does not
contain data on a detailed analysis of color parameters in Yerba Mate infusions prepared in
different thermal conditions, i.e., brewed at 70
◦
C and 100
◦
C, or obtained during a single and
double brewing process.
The research showed significant (p
≤
0.05) differences in the total color difference (
∆
E),
with definitely greater color changes compared to the dried Yerba Mate samples during a
single (average 28.46
±
9.60) than a double (average 20.43
±
5.04) of the brewing process.
Single-brewed Yerba Mate infusions (Table 2) were more than 3 times darker than the
dried samples, because the average BI was 300.93
±
38.77 and 93.16
±
29.59, respectively
(Table 1). The highest (p
≤
0.05)
∆
Evalues were found in YM-C-1-70 infusion (41.66
±
0.37),
which was also characterized by a very high IB (316.68
±
2.24). Double-brewed Yerba Mate
infusions (Table 3) showed an average of almost 30% lower
∆
Evalues than those brewed
once and were almost 2.5 times brighter (the average IB was 125.26
±
22.62). In the case
of double-brewed Yerba Mate infusions, the largest changes (p
≤
0.05) in color compared
to dried samples occurred in the YM-B-2-100 infusion, with the highest
∆
E(28.81
±
0.70)
(Table 3).
In the infusions obtained as a result of different temperature conditions (brewing at
70
◦
C and 100
◦
C) and the number of infusions (1-fold and 2-fold), basic physicochemical
parameters such as pH, total soluble solids (
◦
Brix) and osmolality were assessed and the
results are shown in Table 4(single brewing) and Table 5(double brewing).
Table 4. Physicochemical properties of Yerba Mate infusions obtained as a result of single brewing at
70 ◦C and 100 ◦C.
Sample pH
◦Brix
(%)
Osmolality
(mOsm/kg•H2O)
YM-A-1-70 5.56 ±0.03 d2.07 ±0.06 ab 47.33 ±0.58 b
YM-B-1-70 5.41 ±0.01 b2.07 ±0.06 ab 46.33 ±0.58 ab
YM-C-1-70 5.39 ±0.01 ab 2.07 ±0.06 ab 45.33 ±0.58 a
Molecules 2024,29, 2590 9 of 27
Table 4. Cont.
Sample pH
◦Brix
(%)
Osmolality
(mOsm/kg•H2O)
YM-A-1-100 5.52 ±0.01 c2.17 ±0.06 b55.33 ±0.58 d
YM-B-1-100 5.38 ±0.00 a2.07 ±0.06 ab 51.00 ±1.00 c
YM-C-1-100 5.39 ±0.00 ab 2.03 ±0.06 a51.33 ±0.58 c
Mean values
±
standard deviation with different letters (
a–d
) in the same column differ significantly (Duncan’s
test, p≤0.05).
Yerba Mate infusions were characterized by a similar pH, with a single brewing the pH
was on average 5.44
±
0.07, and with a double brewing it was slightly higher (5.56
±
0.08 on
average). The highest (p
≤
0.05) pH was found in the same Yerba Mate infusion (YM-A),
during single (5.56
±
0.03) (Table 4) and double brewing at 70
◦
C (5.72
±
0.01) (Table 5).
These pH results are confirmed by other authors. Alcarraz et al. (2021) [
57
] obtained the
pH of Yerba Mate infusions from 4.5 to 5.0, while others at the level of about 4.3
±
0.01 [
58
].
Table 5. Physicochemical properties of Yerba Mate infusions obtained as a result of double brewing
at 70 ◦C and 100 ◦C.
Sample pH
◦Brix
(%)
Osmolality
(mOsm/kg•H2O)
YM-A-2-70 5.72 ±0.01 e0.83 ±0.15 c18.33 ±0.58 d
YM-B-2-70 5.54 ±0.01 c0.60 ±0.00 a12.33 ±0.58 b
YM-C-2-70 5.48 ±0.00 a0.70 ±0.00 ab 11.67 ±0.58 a
YM-A-2-100 5.61 ±0.02 d0.77 ±0.06 bc 14.67 ±0.58 c
YM-B-2-100 5.51 ±0.01 b0.70 ±0.00 ab 14.33 ±0.58 c
YM-C-2-100 5.50 ±0.00 b0.70 ±0.00 ab 12.67 ±0.58 b
Mean values
±
standard deviation with different letters (
a–e
) in the same column differ significantly (Duncan’s
test, p≤0.05).
The tested Yerba Mate infusions were characterized by an acidic reaction (pH < 7.0),
which could indicate good microbiological quality of the dried products and their greater
durability due to the inhibition of the development of microorganisms responsible for
product rotting during improper storage conditions [56].
The average soluble solids content in single-brewed Yerba Mate infusions (Table 4)
was 2.08
±
0.06%, in double-brewed (Table 5) it was almost 3 times lower (0.72
±
0.09%).
The highest
◦
Brix was found in YM-A-1-100 (2.17
±
0.06%), and significantly lowest
(p
≤
0.05) in YM-B-2-70 (0.60
±
0.00%). The obtained
◦
Brix values were consistent with the
results of other authors who, in studies on the phytochemical composition of Yerba Mate
(chimarrão) extracts, showed ◦Brix at the level of 1.29 ±0.19% to 3.47 ±0.38% [59].
The tested infusions were also characterized by very low osmolality, with over 3.5 times
higher in single brewing (Table 4) (mean 49.44
±
3.60 mOsm/kg
•
H
2
O) compared to dou-
ble brewing of Yerba Mate (Table 5) (mean 14.00
±
2.33 mOsm/kg
•
H
2
O). The highest
(
p≤0.05
) osmolality, similarly to
◦
Brix, was found in a single-brewed YM-A-1-100 infusion
(55.33
±
0.58 mOsm/kg
•
H
2
O), whereas the lowest (p
≤
0.05) was observed in both, single
(45.33
±
0.58 mOsm/kg
•
H
2
O) and double Yerba Mate brewing (11.67
±
0.58 mOsm/kg
•
H
2
O)
at 70
◦
C. The osmolality of the tested Yerba Mate infusions obtained by double brewing was
similar to the results of other authors, who showed the value of this parameter at the level of
12.8 mOsm/kg•H2O in Yerba Mate infusions [57].
The available literature lacks of data on the effect of brewing conditions, i.e., tem-
perature and number of brewing, on physicochemical parameters such as pH,
◦
Brix or
osmolality in Yerba Mate infusions. Considering the very low
◦
Brix and osmolality val-
ues, the tested infusions could be classified as hypotonic drinks, next to products such as
mineral or spring waters [
60
]. Their absorption from the digestive tract into the cells takes
place very quickly, leading to equally rapid hydration of the body [61].
Molecules 2024,29, 2590 10 of 27
2.2. Bioactive Properties of Different Yerba Mate Infusions
This study investigated the influence of brewing conditions on the content of bioactive
ingredients and the antioxidant activity of Yerba Mate infusions.
2.2.1. Tannins
Figure 4shows the tannin content in Yerba Mate infusions obtained as a result of
single (a) and double (b) brewing at 70 ◦C and 100 ◦C.
The tannin content in single-brewed Yerba Mate infusions ranged from 1.13
±
0.06 up
to 1.51
±
0.02 g/100 g d.m. (mean 1.36
±
0.14 g/100 g d.m.) (Figure 4a), with the tested
samples significantly (p
≤
0.05) differing in this parameter. The lowest tannin concentration
was found in the YM-B-1-70 infusion, significantly higher in YM-C-1-70 and YM-B-1-100
infusions (mean 1.31
±
0.04 g/100 g d.m.), while the highest one was in YM-C-1-100 and
YM-A-1-100 (mean 1.50
±
0.02 g/100 g d.m.). In double-brewed infusions, the tannin
content decreased by about 43.4%), and the average content of these components was
1.36
±
0.12 g/100 g d.m. As in the case of single-brewed samples, the lowest (p
≤
0.05)
tannin content was found in YM-B-2-70 (0.58
±
0.04 g/100 g d.m.) and the highest in
YM-A-2-100 (0.92
±
0.03 g/100 g d.m.). In the available literature, there are no reports on
the influence of conditions such as temperature, time and the number of infusions on the
content of tannins in Yerba Mate infusions. Studies on the tannin content in Yerba Mate in
general are also isolated [19,62].
Figure 4. Tannin content (g/100 g d.m.) in Yerba Mate infusions obtained as a result of single (a)
and double (b) brewing at 70
◦
C and 100
◦
C. Mean values marked in bars by different letters differ
significantly (Duncan’s test, p ≤0.05). (a–d)—values for different samples and brewing temperature
in single (a) and double (b) brewing; (
A–B
)—differences between single (a) and double (b) brewing
for each Yerba Mate sample.
In the studies by Pizarro et al. (1994) [
62
] on the tannin content in herbal teas commonly
consumed in Chile and other Latin American countries, the amount of these ingredients
was higher (11.7 g/100 g d.m.) than in our study. In turn, in the study by Frizon and
Nisgoski (2020) [
19
], the content of these ingredients was similar to that obtained in this
study and ranged from 0.38 up to 3.20 g/100 g d.m. (depending on growing and storage
conditions of Yerba Mate). However, in both cited studies, other techniques were used to
determine the tannin content (i.e., Folin-Denis in the study by Pizarro et al. (1994) [
62
] or
the Prince method in the study by Frizon and Nisgoski (2020) [
19
], not the titration method
(as in experiment), which makes it very difficult to compare quantitative results.
The conducted research also showed the effect of temperature on the tannin content,
both in single (Figure 4a) and double (Figure 4b) Yerba Mate infusions. A higher brewing
temperature (100
◦
C) was accompanied by a higher tannin concentration compared to
infusions obtained in 70
◦
C, i.e., by approx. 12.5% and 16.9% (single and double brewing).
However, the available literature does not contain any data on the effect of temperature on
Molecules 2024,29, 2590 11 of 27
the content of these bioactive ingredients in Yerba Mate infusions. Nevertheless, there are
(albeit single) reports on the effect of brewing conditions on the tannin content in tea [
18
],
an equally common beverage consumed in the form of hot infusions [50].
Dmowski et al. (2011) [
18
] showed significant differences in the content of tannins in
various tea infusions depending on the temperature of the water used for their preparation.
The tannin content in teas brewed at a higher (90
◦
C) temperature ranged from 3.33 to
9.03 g/100 g and was significantly higher than for infusions prepared at a lower (70
◦
C)
temperature (from 1.63 up to 1.97 g/100 g d.m.) [
18
]. Despite the definitely higher tannin
content in tea compared to Yerba Mate infusions, the tendency of changes in the amount of
these components under the influence of temperature in various types of tea was analogous
to our study. Dmowski et al. (2011) [
18
] also showed significant differences in the tannin
content depending on the region of tea origin, with teas from Vietnam and Mozambique
having the highest tannin content, from Argentina lower, and from Malawi the lowest [
18
].
In other study, Jyotismita et al. (2015) [
63
] showed the differences in tannin content
depending on tea production technology, especially on the degree of leaves fermentation
(oxidation) [
63
]. The highest tannin content was found in black tea (mean 13.36% in dry
matter), lower in Oolong, and the lowest in green tea (mean 2.65% in dry matter). Black
teas are the result of complete fermentation of tea leaves, leading to the formation of a
typical brown-black color, resulting from the enzymatic oxidation of catechins present in
tea leaves. Oolong teas are made as a result of incomplete fermentation, while green teas
are produced without this process. Therefore, an important step in the production of green
teas is the phenol oxidase deactivation by using high-temperature heat treatment (steaming
or roasting), which allows the green tea color to be preserved [63].
Comparing the quoted results of the tannin content in various tea types with the
results obtained in this work, it can be concluded that Yerba Mate samples were the most
similar to green teas. Also, in the Yerba Mate production technology, similarities can be
seen. Similarly to the green tea production process, the first (after harvesting holly leaves) is
the heat treatment process (bleaching). It consists in short (2–3 min) smoking at 500–600
◦
C
in order to inactivate the enzymes responsible for oxidation and preserve the characteristic
sensory features, i.e., the color, aroma and taste of the leaves [
2
,
40
,
64
]. As Frizon and
Nisgoski (2020) [
19
] reported, the tannins content in Yerba Mate was significantly different
at different stages of Paraguayan holly treatment. Fresh (green), unheated leaves had
the lowest tannins content (from 0.39 to 0.56 g/100 g d.m.), significantly higher-leaves
subjected to bleaching (from 0.96 up to 2.35 g/100 g d.m.) and the highest (from 1.59 to
3.20 g/100 g d.m.) leaves subjected to preliminary drying at high temperatures.
Also grinding had an impact on the content of these ingredients, changing the
tannin concentration (from 2.21 to 2.25 g/100 g d.m.) as well as storing (from 1.96 to
2.25 g/100 g d.m.
) of ready-made Yerba Mate blends [
19
]. In addition, the same authors
showed that the tannin content varied depending on the growing conditions of Paraguayan
holly, with products obtained from conventional cultivation (usually open areas with more
exposure to light) having higher tannin content than those from organic cultivation (regions
with more shade) at various stages of leaf processing and Yerba Mate production [19].
Tannins present in Yerba Mate, similarly to those in tea, are responsible for the charac-
teristic bitterness and astringency of these infusions [
18
,
19
]. According to the literature, the
optimum water temperature for brewing Yerba Mate is usually between 65
◦
C and 80
◦
C,
and the higher the water temperature, the stronger and bitterer the brew obtained [
2
]. The
organoleptic evaluation of the infusions carried out in this study showed that YM-A-1-100
infusion was marked by the greatest bitterness and astringency, which at the same time had
a significantly (p
≤
0.05) highest tannin content (Figure 4a). It can be concluded that tannins
present in Yerba Mate and the conditions for preparing the infusions play an important
role in shaping the organoleptic characteristics and bioactive properties of the beverages
obtained in this way.
Molecules 2024,29, 2590 12 of 27
2.2.2. Caffeine
Figure 5shows the caffeine content in Yerba Mate infusions obtained as a result of
single (a) and double (b) brewing at temperatures of 70 ◦C and 100 ◦C.
Figure 5. Caffeine content (mg/g d.m.) in Yerba Mate infusions obtained as a result of single (a)
and double (b) brewing at 70
◦
C and 100
◦
C. Mean values marked in bars by different letters differ
significantly (Duncan’s test, p
≤
0.05). (
a–e
)—values for different samples and brewing temperature
in single (a) and double (b) brewing; (
A–B
)—differences between single (a) and double (b) brewing
for each Yerba Mate sample.
The caffeine content in the infusions obtained as a result of single brewing ranged from
13.51
±
0.02 mg/g d.m. up to 22.02
±
0.95 mg/g d.m. (average 17.79
±
3.49 mg/g d.m.)
(Figure 5a), and the tested samples differed significantly (p
≤
0.05) in terms of this component.
The lowest caffeine content was found in YM-B-1-100, YM-C-1-100 and YM-B-1-70 infusions
(average 14.66
±
1.12 mg/g d.m.), significantly higher in YM-A-1-100 (
19.20 ±0.48 mg/g d.m.
),
and the highest in YM-C-1-70 and YM-A-1-70 (average 21.79
±
1.16 mg/g d.m.). As a result of
double brewing, a reduction in caffeine content was found. The average content of this alkaloid
in twice-brewed samples was 14.28
±
5.80 mg/g d.m. and (similarly to those brewed once) the
lowest (p
≤
0.05) content was found in YM-B-2-100 infusion (
5.86 ±0.01 mg/g d.w.
), while the
highest in YM-A-2-70 (20.50 ±0.16 mg/g d.w.) (Figure 5b).
According to the literature, the caffeine content in Yerba Mate is usually in the range
of 1 to 2% in dry matter [
2
,
53
] and can range from approx. 25 to 175 mg/g d.m. [
6
,
26
,
65
],
which was confirmed by the research conducted in this study (0.6% to 2.2% in dry matter).
In the literature, there are single studies on the influence of Yerba Mate brewing condi-
tions, such as temperature, time and number of brewings, on the caffeine content in Yerba
Mate [
53
,
66
]. Meinhart et al. (2010) [
53
] showed a significant decrease in caffeine concentration
during multiple brewing of Yerba Mate at 75
◦
C for 30 s, i.e., from 13.7–26.4 mg/100 mL of
infusion (during a single brewing) to 1.5–6.6 mg/100 mL in 30-brewed Yerba Mate chimarrão.
These authors showed a similar tendency for multiply brewed Yerba Mate tereréat a lower
(11
◦
C) temperature at the same time (30 s). In this case, the caffeine content in single infusions
was approx. 35.8 mg/100 mL, while after 30 infusions it was only 2.9 mg/100 mL [
53
]. This
tendency was also confirmed by the research conducted in this study, as double brewing
resulted in a reduction in the caffeine content by approx. 19.7% compared to single-brewed
Yerba Mate infusions.
Kruszewski et al. (2012) [
66
] also showed that the caffeine content in Yerba Mate
infusions increases with the extension of the brewing time, from 15 mg/100 mL of the
infusion prepared in 15 min to 25.8 mg/100 mL in 60 min at 70
◦
C, while for Yerba Mate
brewed in boiling water (100
◦
C) from 11.8 mg/100 mL (15 min.) to 15.8 mg/100 mL
(60 min.). The research of these authors also shows that the concentration of caffeine in
infusions prepared at a higher temperature (100
◦
C) is significantly lower compared to
infusions obtained at 70
◦
C, which was confirmed by our research. Yerba Mate samples
Molecules 2024,29, 2590 13 of 27
brewed once at 100
◦
C had lower caffeine content, on average by 1.87
±
0.04 mg/g d.m.
(YM-B-1), 2.82
±
0.75 mg/g d.m. (YM-A-1) and 6.48
±
0.71 mg/g d.m. (YM-C-1) than
those brewed at 70
◦
C. A similar relationship was found in double-brewed Yerba Mate infu-
sions, for which the caffeine concentration was lower, on average by
2.23 ±0.04 mg/g d.m.
(YM-B-2), 2.60
±
0.55 mg/g d.m. (YM-A-2) and 5.78
±
1.52 mg/g d.m. (YM-C-2) in the case
of samples steamed at a higher temperature, i.e., in boiling water (100 ◦C) than at 70 ◦C.
The results of the qualitative and quantitative analysis of selected bioactive com-
pounds, i.e., carotenoids, phenolic acids and flavonoids identified by HPLC in Yerba Mate
infusions are presented in Table 6(single brewing at 70
◦
C and 100
◦
C) and in Table 7
(double brewing at 70 ◦C and 100 ◦C).
Table 6. Selected phenolic compounds identified by the HPLC method in the tested Yerba Mate
infusions obtained as a result of single brewing at 70 ◦C and 100 ◦C.
Bioactive Compounds
(mg/g d.m.) YM-A-1-70 YM-B-1-70 YM-C-1-70 YM-A-1-100 YM-B-1-100 YM-C-1-100
Gallic acid 0.45 ±0.00 a2.25 ±0.03 c2.45 ±0.08 d0.47 ±0.00 a0.55 ±0.02 b2.40 ±0.01 d
Chlorogenic acid 25.64 ±0.36 c24.47 ±0.03 b27.05 ±0.86 d24.15 ±0.16 b7.94 ±0.12 a25.30 ±0.43 c
Caffeic acid 3.82 ±0.08 b35.86 ±2.54 a0.62 ±0.03 a3.68 ±0.04 b23.11 ±0.56 c0.43 ±0.04 a
p-coumaric acid 38.15 ±0.04 e32.20 ±0.39 b36.81 ±0.14 d38.56 ±0.29 e12.86 ±0.86 a34.01 ±0.44 c
Ferulic acid 1.87 ±0.02 c0.31 ±0.02 a0.36 ±0.00 a1.64 ±0.02 b3.31 ±0.09 d0.30 ±0.01 a
Salicylic acid 1.98 ±0.02 d0.51 ±0.06 a0.69 ±0.02 b0.56 ±0.01 a0.91 ±0.05 c0.56 ±0.00 a
t-cinnamic acid 7.03 ±0.08 c7.48 ±0.03 e7.30 ±0.07 d2.77 ±0.01 a8.43 ±0.09 f6.08 ±0.05 b
Total phenolic acids * 78.95 ±0.49 f67.58 ±0.82 b75.29 ±0.92 e71.83 ±0.18 d57.10 ±0.61 a69.09 ±0.45 c
Rutoside-3-O-quercetin 2.60 ±0.04 e2.11 ±0.07 d2.02 ±0.01 c1.18 ±0.04 b0.93 ±0.01 a0.93 ±0.03 a
Glycoside-3-O-quercetin 4.08 ±0.07 e3.19 ±0.03 c3.54 ±0.03 d1.40 ±0.07 a1.87 ±0.02 b1.90 ±0.03 b
Myricetin 0.94 ±0.01 d0.75 ±0.01 b0.90 ±0.01 c1.64 ±0.02 e0.65 ±0.01 a0.63 ±0.00 a
Apigenin 0.10 ±0.01 b0.54 ±0.02 c0.70 ±0.01 d0.06 ±0.00 a0.09 ±0.00 ab 0.09 ±0.00 b
Total flavonoids * 7.71 ±0.09 e6.59 ±0.12 c7.16 ±0.06 d4.28 ±0.05 b3.54 ±0.03 a3.56 ±0.03 a
Lutein #8.49 ±0.03 c8.02 ±0.07 a8.19 ±0.03 b8.40 ±0.04 c7.99 ±0.05 a8.27 ±0.08 b
α-carotene #3.50 ±0.01 c3.37 ±0.01 a3.46 ±0.01 b3.48 ±0.02 bc 3.36 ±0.01 a3.47 ±0.01 b
β-carotene #1.10 ±0.05 b0.81 ±0.05 a1.27 ±0.08 bc 1.70 ±0.04 d1.32 ±0.04 c1.19 ±0.23 bc
Total carotenoids *#13.09 ±0.07 c12.20 ±0.08 a12.92 ±0.04 c13.58 ±0.08 d12.67 ±0.08 b12.93 ±0.28 c
Mean values
±
standard deviation with different letters (
a–f
) in the same line differ significantly (Duncan’s test,
p
≤
0.05). *—total phenolic acids, total flavonoids and total carotenoids expressed as the sum of identified
bioactive compounds. #—lutein, α-carotene, β-carotene, total carotenoids expressed in µg/g d.m.
Table 7. Selected phenolic compounds identified by the HPLC method in the tested Yerba Mate
infusions obtained as a result of double brewing at 70 ◦C and 100 ◦C.
Bioactive Compounds
(mg/g d.m.) YM-A-2-70 YM-B-2-70 YM-C-2-70 YM-A-2-100 YM-B-2-100 YM-C-2-100
Gallic acid 2.44 ±0.09 e0.43 ±0.00 a0.89 ±0.02 b0.87 ±0.01 b1.23 ±0.04 c1.46 ±0.09 d
Chlorogenic acid 3.28 ±0.11 a15.24 ±0.45 e5.47 ±0.07 b7.89 ±0.08 d6.64 ±0.04 c5.62 ±0.13 b
Caffeic acid 30.90 ±0.22 f12.81 ±0.07 c12.21 ±0.34 b22.63 ±0.07 d2.41 ±0.02 a24.40 ±0.14 e
p-coumaric acid 8.93 ±0.10 a19.92 ±0.12 d39.80 ±0.20 e14.67 ±0.16 b16.92 ±0.11 c8.87 ±0.10 a
Ferulic acid 4.25 ±0.49 c5.33 ±0.06 d3.67 ±0.05 b3.23 ±0.01 a4.14 ±0.06 c5.33 ±0.02 d
Salicylic acid 2.62 ±0.13 d1.57 ±0.05 c0.48 ±0.00 a0.95 ±0.04 b1.47 ±0.03 c3.08 ±0.01 e
t-cinnamic acid 13.50 ±0.29 f1.73 ±0.04 a2.71 ±0.01 b9.06 ±0.05 d7.51 ±0.25 c9.95 ±0.05 e
Total phenolic acids * 65.91 ±0.62 e57.03 ±0.46 b65.23 ±0.18 d59.31 ±0.01 c40.32 ±0.21 a58.71 ±0.37 c
Rutoside-3-O-quercetin 1.25 ±0.02 a1.60 ±0.03 b2.01 ±0.01 c1.58 ±0.02 b1.55 ±0.04 b1.58 ±0.04 b
Glycoside-3-O-quercetin 1.51 ±0.02 d0.99 ±0.01 b1.07 ±0.01 c0.90 ±0.02 a1.00 ±0.03 b0.93 ±0.03 a
Myricetin 2.34 ±0.00 f0.50 ±0.01 b0.68 ±0.00 d0.84 ±0.01 e0.45 ±0.01 a0.52 ±0.01 c
Apigenin 0.08 ±0.00 b0.08 ±0.00 ab 0.13 ±0.00 c0.07 ±0.02 ab 0.06 ±0.00 a0.14 ±0.01 c
Total flavonoids * 5.18 ±0.03 e3.16 ±0.04 b3.89 ±0.00 d3.38 ±0.03 c3.06 ±0.03 a3.18 ±0.04 b
Lutein #9.25 ±0.05 cd 8.11 ±0.07 a8.60 ±0.05 b9.49 ±0.15 d8.20 ±0.28 a9.11 ±0.05 c
α-carotene #3.23 ±0.02 bc 3.15 ±0.01 a3.33 ±0.01 d3.26 ±0.01 c3.21 ±0.03 b3.22 ±0.02 b
β-carotene #0.65 ±0.00 c0.58 ±0.01 b0.82 ±0.02 e0.69 ±0.03 d0.52 ±0.03 a0.59 ±0.03 b
Total carotenoids *#13.14 ±0.05 c11.84 ±0.08 a12.75 ±0.03 b13.44 ±0.17 d11.93 ±0.30 a12.93 ±0.02 bc
Mean values
±
standard deviation with different letters (
a–f
) in the same line differ significantly (Duncan’s test,
p
≤
0.05). *—total phenolic acids, total flavonoids and total carotenoids expressed as the sum of identified
bioactive compounds. #—lutein, α-carotene, β-carotene, total carotenoids expressed in µg/g d.m.
Molecules 2024,29, 2590 14 of 27
2.2.3. Carotenoids
The tested Yerba Mate samples were characterized by a high content of carotenoids,
with the sum of identified ingredients on average 12.90
±
0.44
µ
g/g d.m. in single-brewed
(Table 6) and 12.67
±
0.62
µ
g/g d.m. in double-brewed (Table 7) infusions. The highest
(p
≤
0.05) content of these compounds was found in YM-A samples brewed at 100
◦
C, both
during single (YM-A-1-100) and double (YM-A-2-100) brewing (13.58
±
0.08
µ
g/g d.w. and
13.44
±
0.17
µ
g/g d.w., respectively), the lowest (p
≤
0.05) in YM-B samples brewed at
70
◦
C, both during a single brewing (YM-B-1-70), as well as double brewing (YM-B-2-70)
(12.20 ±0.08 µg/g d.m. and 11.84 ±0.08 µg/g d.m., respectively).
HPLC analysis identified three carotenoid compounds, i.e., lutein,
α
-carotene and
β
-carotene. The dominant ingredient was lutein, 63.79
±
1.35% (single brewing) and
69.36
±
1.27% (double brewing) of total carotenoids.
α
-carotene had a much smaller share
in this fraction of bioactive ingredients (26.70
±
0.65% and 25.56
±
1.06%), while
β
-carotene
accounted for only 9.50
±
1.95% and 5.07
±
0.69% (for samples brewed once and twice,
respectively). According to the literature, lutein is the main carotenoid from the xanthophyll
group, present in green leaves and green vegetables [67,68].
There are few studies in the available literature on the content and profile of carotenoids
in Yerba Mate, and the existing ones indicate a very large diversity of these ingredients. For
example, in studies on the influence of a controlled atmosphere on the quality of Yerba Mate
during long-term (10 months) storage, Thewes et al. (2016) [
69
] showed the carotenoid
content ranging from 92.93
µ
g/g f.w. up to 107.9
µ
g/g f.w. (at the beginning of storage
tests), from 152.6
µ
g/g f.w. to 465.9
µ
g/g f.w. (in various shelf life periods, 1–4 weeks),
or from 139.7
µ
g/g f.w. to 589.9
µ
g/g f.w. (after 10 months of storage), depending on the
type of crop and different storage conditions of Yerba Mate. However, these tests were not
carried out in infusions, but in Yerba Mate samples stored after harvest.
The use of different brewing conditions for Yerba Mate slightly influenced the content
of identified total carotenoids (lower by less than 2% in double-brewed infusions). However,
it is worth paying attention to the profile of these ingredients. Both in infusions brewed
once (Table 6) and twice (Table 7), the content of total carotenoids was higher at higher
temperature (100
◦
C). A similar tendency was shown by da Silveira et al. (2016) [
68
] for
lutein in water extracts in four types of Yerba Mate (commercial products differing, among
others, in the degree of granulation). The degree of lutein migration into aqueous extracts
increased with increasing temperature. In traditional Yerba Mate, brewed at 67
◦
C, 75
◦
C,
85
◦
C and 95
◦
C, it increased from 1.99
±
0.26
µ
g/100 mL to 2.13
±
0.72
µ
g/100 mL. In turn,
in the coarse-ground Yerba Mate, lutein content increased from 2.35
±
0.57
µ
g/100 mL to
5.00
±
1.95
µ
g/100 mL of extract [
68
]. In our research, such a relationship was observed for
lutein during double brewing of Yerba Mate (Table 7).
2.2.4. Phenolic Acids and Flavonoids
According to the conducted research, Yerba Mate infusions were characterized by
a high content of phenolic compounds, with the sum of identified ingredients on aver-
age 75.44
±
8.46 mg/g d.m. in single-brewed (Table 6) and 61.40
±
9.22 mg/g d.m. in
double-brewed (Table 7) Yerba Mate samples. The obtained results coincide with those of
other authors, who showed the content of these compounds in Yerba Mate at the level of
80-97 mg/g d.m. [
25
,
70
]. According to the literature, the fraction of polyphenolic com-
pounds in Yerba Mate leaves may constitute from 7 to 10% of dry matter [71].
Based on the results, it can be concluded that in both once (Table 6) and twice (Table 7)
brewed infusions, the main fraction of phenolic compounds were phenolic acids, the share
of which (in all identified ingredients) was 92.87
±
1.76% and 94.04
±
0.90%, respectively.
In the infusions obtained as a result of single brewing, p-coumaric acids (45.1%) and
chlorogenic acids (31.5%) dominated among the identified phenolic acids. t-cinnamic (9.5%)
and caffeic (8.7%) acids had a much smaller, and gallic (2.0%), ferulic (2.0%) and salicylic
(1.2%) acids had the smallest share. In the case of infusions obtained as a result of double
brewing, the dominant acids were p-coumaric (31.9%) and caffeic (28.9%), while the lower
Molecules 2024,29, 2590 15 of 27
share had chlorogenic (13.2%), t-cinnamic (13.1%), and ferulic (7.7%) acids. The smallest
ones were salicylic (3.0%) and gallic (2.1%) acids.
The obtained results were partially confirmed by other authors. Bravo et al. (2007) [
25
]
found that phenolic acids constitute (as in our work) over 90% of the content of all phenolic
compounds, with quinic acid dominating. According to the authors, 80% of all compounds
were 9 main phenolic components belonging to hydroxycinnamoyl quinic acid esters and
flavonol glycosides [
25
]. Research by Piovezan-Borges et al. (2016) [
72
] also confirmed
that the main fraction of phenolic compounds are hydroxycinnamates, but mainly these
are caffeic acid esters and other hydroxycinnamic acids, such as ferulic, p-coumaric acid,
or caffeic acid, constituting up to 95% of the content of all phenolic compounds. The
remaining 5% of the PC fraction consists of flavonols [
72
]. Piovezan-Borges et al. (2016) [
72
]
also confirmed that the main fraction of phe-nolic compounds are hydroxycinnamates,
but mainly these are caffeic acid esters and other hydroxycinnamic acids, such as ferulic,
p-coumaric or caffeic acids, constituting up to 95% of all phenolic compounds. The remain-
ing 5% of the phenolic compounds consists of flavonols fraction [72]. Also Cheminet et al.
(2021) [
73
] showed over 90% share of phenolic acids in the identified phenolic compounds,
showing the highest share of caffeoylshiquimic (70%), much lower for feruroylquinic
acids (7.0%) and dicaffeoylquinic (5.5%) acids [
73
]. Similarly, in the study by Mateos et al.
(2017) [
70
], the main group of phenolic compounds were phenolic acids with a predominant
share in this fraction of caffeoylquinic acids, of which 3-caffeoylquinic, 5-caffeoylquinic
and 4-caffeoylquinic acids were the dominant compounds (26.8–28.8%, 21.1–22.4% and
12.6–14.2% of all phenolic compounds, respectively) [
70
]. Also, Konieczy´nski et al. (2017) [
50
],
among the main phenolic compounds, mentioned phenolic acids, including caffeic (from
6.92
±
2.22 mg/g d.m. to 9.96
±
0.22 mg/g d.m.), ferulic (from 1.12
±
0.00 mg/g d.m. up
to 1.48
±
0.02 mg/g d.m.), gallic (from 0.45
±
0.01 mg/g d.m. to 0.49
±
0.09 mg/g d.m.)
and p-coumaric (from 0.06 ±0.01 mg/g d.m. to 0.09 ±0.00 mg/g d.m.) acids [50].
HPLC analysis showed that the second significant group of phenolic compounds
in the tested Yerba Mate samples were flavonoids. The average concentration of these
compounds in single-brewed (Table 6) and double-brewed (Table 7) infusions was
5.47
±
1.78 mg/g d.m. and 3.64
±
0.76 mg/g d.m., which represented 7.13
±
1.76% and
5.96
±
0.90% of all phenolic compounds identified by this method, respectively. Of the four
identified flavonoids in single-brewed Yerba Mate infusions, two dominated, i.e., glycoside-
3-O-quercetin (48.3%) and rutoside-3-O-quercetin (29.0%), while myricetin (18.4%) and
apigenin (4.3%) had a smaller share (Table 6). In turn, in double-brewed Yerba Mate
infusions, the dominant flavonoid was rutinoside-3-O-quercetin (45.5%), a much smaller
share had glycoside-3-O-quercetin (29.4%), then myricetin (22.5%) and apigenin (2.6%)
(Table 7).
The obtained results were confirmed in studies by other authors. According to the
literature, in terms of concentration, flavonoids constitute the second fraction of phenolic
components in Yerba Mate (up to 10% of all phenolic compounds) [25–27,46,70,73].
The most frequently identified flavonoids in Yerba Mate include: rutinoside-3-O-
quercetin, glycoside-3-O-quercetin, rhamnoside-3-O-quercetin, 3-rhamnoside and 3-
glycoside of kaempferol, luteolin diglycoside, rutin, catechin, quercetin, myricetin and
apigenin [
2
,
25
–
27
,
46
,
50
,
70
], as well as rutoside and astragalin [
23
], but the literature does
not agree on the compounds dominant in this fraction. Some studies show the dominant
share (up to 90% of identified flavonoids) of rutin [
25
,
70
], others of rutoside [
23
], still others
of quercetin [50], or rutinoside-3-O-quercetin [73].
The conducted research showed significant (p
≤
0.05) differences in the profile and
content of individual fractions of polyphenolic compounds between single-brewed Yerba
Mate samples (Table 6). The highest (p
≤
0.05) content of phenolic acids and flavonoids was
found in the YM-A-1- 70 (78.95
±
0.49 mg/g d.m. and 7.71
±
0.09 mg/g d.m., resp.), lower
in YM-C-1-70 (75.29 0.92 mg/g d.m. and 7.16
±
0.06 mg/g d.m., resp.), the lowest (p
≤
0.05)
in YM-B-1-100 (57.10
±
0.61 mg/g d.m. and 3.54
±
0.03 mg/g d.m., resp.). A similar trend
occurred in double-brewed Yerba mate samples (Table 7). The highest total phenolic acids
Molecules 2024,29, 2590 16 of 27
and flavonoids was found in YM-A-2-70 (65.91
±
0.62 mg/g d.m. and 5.18
±
0.03 mg/g d.m.,
resp.) and YM-C-2-70 (65.23
±
0.18 mg/g d.m. and 3.89
±
0.00 mg/g d.m., resp.), significantly
lower in YM-A-2-100 (59.31
±
0.01 mg/g d.m. and 3.38
±
0.03 mg/g d.m., resp.), and the
lowest (p≤0.05) in YM-B -2-100 (40.32 ±0.21 mg/g d.m. and 3.06 ±0.03 mg/g d.m., resp.).
The available literature does not contain any data on the impact of different brewing
conditions, i.e., the number of brewing or temperature, on the profile and content of phe-
nolic acids and flavonoids in Yerba Mate. It is worth noting here, that YM-A and YM-C
samples brewed at a lower temperature (70
◦
C) were characterized by a higher content of
phenolic acids, i.e., chlorogenic, caffeic, ferulic, salicylic and t-cinnamic acids. In the case of
gallic, chlorogenic and p-coumaric acid, this tendency was also shown by YM-B sample. In
turn, in the case of flavonoids, all Yerba Mate samples brewed at a lower temperature
(70
◦
C) showed a higher content of each of these compounds compared to samples
brewed in boiling water (100
◦
C). The exception was the YM-A sample, where no such
relationship was found only in the case of myricetin. Interestingly, the concentration
of this ingredient was the highest (p
≤
0.05) in YM-A-1-100 sample (brewed at 100
◦
C)
(1.64 ±0.02 mg/g d.m.
) among all the analyzed samples (Table 6). In the case of infusions
obtained as a result of double brewing (Table 7), these relationships were not so clear and
were characterized by greater diversity in the case of individual bioactive compounds.
Taking into account the huge diversity of phenolic compounds, complex biosynthetic
pathways and metabolism of individual components, as well as the significant impact of
both genetic, environmental and processing factors on the profile of phenolic compounds in
Yerba Mate [
50
,
70
,
73
], further research is necessary, in particular to precisely determine the
qualitative and quantitative composition of individual phenolic compounds, for a better
understanding of their bioactivity in the case of consumption of Yerba Mate as a potential
functional food [70,73].
2.2.5. Total Polyphenols
Figure 6shows the total polyphenol content in Yerba Mate infusions obtained as a
result of single (a) and double (b) brewing at 70 ◦C and 100 ◦C.
Figure 6. Total polyphenol content (mg GAE/g d.m.) in Yerba Mate infusions obtained as a result
of single (a) and double (b) brewing at 70
◦
C and 100
◦
C. Mean values marked in bars by different
letters differ significantly (Duncan’s test, p
≤
0.05). (
a–f
)—values for different samples and brewing
temperature in single (a) and double (b) brewing; (
A–B
)—differences between single (a) and double
(b) brewing for each Yerba Mate sample.
Studies have shown a high content of total polyphenolic compounds, both in infusions
obtained as a result of single brewing (average 55.26
±
8.51 mg GAE/g d.M.) (Figure 6a)
and as a result of double brewing (average 32.19
±
6.30 mg GAE/g d.m.) (Figure 6b), while
the average content of these ingredients was significantly (p
≤
0.05) lower (by approx. 40%)
in the infusions obtained in the second brewing. Moreover, differences in the content of
total polyphenols were found depending on the applied temperature. The total polyphenol
content in the infusions obtained as a result of the first brewing (Figure 6a) at 70
◦
C was on
Molecules 2024,29, 2590 17 of 27
average 57.47
±
8.66 mg GAE/g d.m. and was slightly higher than in infusions obtained at
100
◦
C (53.04
±
7.98 mg GAE/g d.m.). A similar trend was also observed after the second
brewing (Figure 6b). Yerba Mate samples brewed at 70
◦
C were characterized by a slightly
higher content of total polyphenols (34.69
±
6.59 mg GAE/g d.m.) than those brewed at
100 ◦C (32.19 ±6.30 mg GAE/g d.m.).
According to the literature, the optimum temperature of water for brewing Yerba
Mate, ensuring moderate bitterness, taste and aroma, is usually in the range of 65
◦
C to
80
◦
C [
2
]. However, in the available literature, there is little research on the effect of brewing
temperature on the content of bioactive ingredients in Yerba Mate. In studies on the effect
of water temperature of chimarrãoinfusions on the content of caffeic acid, five isomers of
chlorogenic acid and rutin in two types of Yerba Mate (traditional and coarse), a significant
effect of temperature on the content of these phenolic compounds was shown, with the
highest concentration of all tested bioactive ingredients at 95
◦
C, approx. 30% lower at
65
◦
C, approx. 33% lower at 85
◦
C, and the lowest at 75
◦
C [
22
]. The authors explained
this relationship with probably better solubility of these components in water at high
(close to boiling) temperature [
74
]. In our study, an inverse relationship was found, but
they concerned the total content of phenolic compounds and not changes in individual
bioactive compounds.
The conducted studies also showed significant (p
≤
0.05) differences in the total
polyphenol content between all Yerba Mate samples brewed once (Figure 6a), with the
highest content of these ingredients found in YM-A-1-70 (64.06
±
1.11 mg GAE/g d.m.),
lower in YM-C-1-70, YM-A-1-100, YM-C-1-100 and YM-B-1-70 and significantly (p
≤
0.05)
lowest in YM-B-1-100 (42.38
±
0.94 mg GAE/g d.m.). Da Silveira et al. (2021) [
22
] showed a
higher content of selected bioactive ingredients in coarse-grained Yerba Mate, compared to
traditional Yerba Mate, which in turn was confirmed in this study, because the sample with
the highest degree of fragmentation (YM-A) (Figure 1a) was characterized by the highest
content of total polyphenols, in contrast to the YM-B sample, with the lowest degree of
fragmentation and the highest share in the mixture of finely cut twigs and sticks (Figure 1b),
showing the lowest content of these phytonutrients.
The results of total polyphenol content in single-brewed Yerba Mate infusions were con-
firmed by other authors [
17
,
49
,
59
]. Comparing various leaf extracts, Pinto et al. (2020) [
59
]
showed from 55.23
±
1.41 to 58.98
±
0.10 GAE/g d.m. total polyphenols in aqueous extracts,
from 54.48
±
1.19 to 58.71
±
0.82 GAE/g d.m. in ethanol extracts, while in ethanol:water
(1:1) extracts, ranged from 58.88
±
1.05 to 65.78
±
1.54 mg GAE/g. Lower values (
29.4 ±0.4
to 39.7
±
0.4 mg GAE/g d.m.) were obtained by Dmowski and Post (2018) [
49
] in single
brewing Yerba Mate infusions. Similar, although slightly higher, values (71.6
±
10.9 to
75.4
±
5.7 mg GAE/g d.m.) were reported by Duarte et al. (2022) [
17
] in dried leaves of var-
ious Yerba Mate morphotypes. In other studies, total polyphenol content ranged from 76.47
to 84.88 GAE/g d.m. (average 80 mg GAE/g d.m.) [
70
], or from 81 to
97 mg GAE/g d.m. [25]
.
According to the literature, the content of total polyphenols varies depending on
different parts of Yerba Mate, and compared to extracts from whole plants or twigs, the
highest content is found in leaf extracts [
6
,
25
–
27
,
44
,
46
]. The total polyphenols content
and other bioactive ingredients in Yerba Mate is also influenced by the methods of leaf
treatment, e.g., the polyphenols in fresh leaves was 4.15 mg GAE/g d.m., in blanched
“zapecada” 98.86 mg GAE/g d.m., in pre-dried 90.23 mg GAE/g d.m., dried-candchada
96.07 mg GAE/g d.m. and in forced aged leaves even 101.00 mg GAE/g d.m. [
20
]. Other
authors showed a much higher share of total polyphenols in extracts from lyophilized
commercial Yerba Mate products, reaching 143.2
±
7.8 mg GAE/g of lyophilisate [
75
],
while De Mejía et al. (2010) [
26
] in commercial samples of traditional Yerba Mate Instant
produced from holly leaves from Argentina and Paraguay recorded the share of these
phytochemicals even at the level of 244.9 ±59.3 up to 321.8 ±74.1 mg GAE/g d.m.
Yerba Mate samples brewed twice (Figure 6b) were characterized by a slightly lower
total polyphenol content, however, similarly to the first brewing, the highest (p
≤
0.05)
content of these components was found in the YM-A-2-70 (40.11
±
1.72 mg GAE/g d.m.),
Molecules 2024,29, 2590 18 of 27
and the lowest in YM-B-2-100 (23.80
±
1.32 mg GAE/g d.m.). The double brewing process
reduced the polyphenols content of around 22.78
±
2.63 mg GAE/g d.m. (at 70
◦
C) and
20.85
±
2.77 mg GAE/g d.m. (at 100
◦
C). It is worth noting, that despite the lowest content
of polyphenols in the YM-B-2-100, it showed the smallest losses of these ingredients (on
average by approx. 18.58
±
1.81 mg GAE/g d.m.), in contrast to the YM-A-2-70 sample
(with the highest content of polyphenols), in which the losses of these components after the
second brewing were the highest and amounted to 23.97 ±2.42 mg GAE/g d.m.
In the available literature, there are single studies on the influence of the multiplicity
of Yerba Mate infusions on the content of polyphenolic compounds. Dmowski and Post
(2018) [
49
] showed from 27.5
±
02 up to 39.7
±
0.4 mg GAE/g d.m. total polyphenols
during the first brewing and a much higher (by about 55–59%) compared to the present
study decrease in the content of these components during the second brewing (11.4
±
0.4
to 17.1
±
0.1 mg GAE/g d.m.). The next (third) brewing decreased polyphenols content
(an average of another 45–67%), reaching only 3.7
±
0.1 to 9.3
±
0.2 mg GAE/g d.m. [
49
].
A similar trend was also shown by Colpo et al. (2016) [
65
] for commercial Yerba Mate
products from Brazil, Argentina and Uruguay. Compared to the first brewing, the total
polyphenol content in the second brewing decreased (similarly to our study) by about
40–45%, and each subsequent brewing led to further losses of these bioactive ingredients.
In the Meinhart et al. (2010) [
53
] studies, the decrease in polyphenols content between
the second and first brewing ranged from 48.6% to 55.5% in chimarrãoinfusions from
various Yerba Mate commercial samples (smooth, traditional, native, course-ground), and
each subsequent brewing reduced the content of these ingredients [
53
]. However, in the
case of tereré(low-temperature brewing), the first 3–4 brewing resulted in polyphenols
increase, and only the 4–5th brewing resulted in a significant decrease [
53
]. Based on the
literature and conducted research, from the point of view of polyphenol content, apart
from the number of infusions, the temperature and the method of infusion preparation are
also important.
2.2.6. Antioxidant Activity
Considering that the tested Yerba Mate infusions provided a large amount of polyphe-
nolic components, known as a strong antioxidants [
9
,
16
,
17
,
20
,
23
], the effect of single (a)
and double (b) brewing at 70
◦
C and 100
◦
C on antioxidant activity in Yerba Mate was
examined in this study and the results are presented in Figure 7.
Figure 7. Antioxidant activity (
µ
M TEAC/g d.m.) in Yerba Mate infusions obtained as a result of
single (a) and double (b) brewing at 70
◦
C and 100
◦
C. Mean values marked in bars by different
letters differ significantly (Duncan’s test, p
≤
0.05). (
a–f
)—values for different samples and brewing
temperature in single (a) and double (b) brewing; (
A–B
)—differences between single (a) and double
(b) brewing for each Yerba Mate sample.
The infusions obtained during the first brewing (Figure 7a) were characterized by sig-
nificantly higher antioxidant activity (mean 2031.98
±
146.47
µ
M TEAC/g d.m.) compared
Molecules 2024,29, 2590 19 of 27
to the infusions obtained after the second brewing (Figure 7b) (mean 1683.09
±
155.34
µ
M
TEAC/g d.m.), while (as in the case of total polyphenol content) slightly higher antioxidant
potential was found in Yerba Mate samples brewed at 70
◦
C (mean 2081.69
±
144.52
µ
M
TEAC/g d.m. and 1704.24
±
159.64
µ
M TEAC/g d.m., in the first and second brewing,
respectively) than those brewed at 100
◦
C (on average 1982.26
±
138.34
µ
M TEAC/g d.m.
and 1661.93 ±157.42 µM TEAC/g d.m., for the first and second brewing, respectively).
Among the single-brewed infusions (Figure 7a), the lowest (p
≤
0.05) antioxidant
activity was found in YM-B-1-100 (1801.44
±
18.18
µ
M TEAC/g d.m.), higher values were
noted for YM-B-1-70, YM-C-1-100, YM-A-1-100, YM-C-1-70, and the highest (p
≤
0.05)
in the YM-A-1-70 (2213.76
±
7.10
µ
M TEAC/g d.m.). Double brewing of Yerba Mate
caused a significant (p
≤
0.05) reduction in the antioxidant properties. The lowest (p
≤
0.05)
antioxidant activity was recorded for YM-B-2-100 (1452.34
±
9.09
µ
M TEAC/g d.m.) and
the highest for YM-A-2-70 (1823.26 ±5.95 µM TEAC/g d.w.) (Figure 7b).
According to the literature, Yerba Mate is characterized by a high antioxidant po-
tential measured not only by the ability to deactivate ABTS
+•
radicals [
20
,
59
,
70
,
76
],
but also DPPH [
16
,
17
,
23
,
45
,
46
,
48
,
59
,
64
,
75
,
77
], or measured using FRAP [
23
,
25
,
70
,
76
] or
ORAC [
16
,
70
,
75
,
77
]. Most studies used different research methods and analytical proce-
dures (e.g., extraction, standard substances) and the results were expressed in different
units, which makes it very difficult to compare them with the results obtained in this work.
Nevertheless, Mesquita et al. (2021) [
16
] showed similar antioxidant activity (from
1626
±
0.22 to 1924
±
0.16
µ
M TEAC/g) in Mate-Tea extracts, as did Mateos et al. (2018) [
70
]
(2172.96
±
169.15
µ
M TEAC/g to 2433.98
±
241.71
µ
M TEAC/g) in various Yerba Mate
commercial products. However, Mesquita et al. (2021) [
16
] also showed significantly
higher antioxidant potential in tereréextracts (6194
±
0.39 to 7726
±
0.33
µ
M TEAC/g)
or chimarrão(from 8246
±
0.43 to 9106
±
0.42
µ
M TEAC/g). In turn, in other studies, the
antioxidant activity was much lower, i.e., from 830.6
±
64.2 to 925.8
±
99.5
µ
M TEAC/g
d.m., depending on the different Yerba Mate morphotypes [
17
], from 410.50
±
15.97 to
438.15
±
18.39
µ
M TEAC/g d.m.) in various commercial Yerba Mate products, or it varied
depending on the type of extraction used: from 297
±
13 up to 353
±
18
µ
M TEAC/g d.m.
(aqueous extracts), from 275
±
19 up to 352
±
9
µ
M TEAC/g d.m. (ethanol extracts), or
from 176 ±7.0 up to 270 ±11 µM TEAC/g d.m. (ethanol extracts: water, 1:1) [70].
This study showed that the antioxidant activity of Yerba Mate infusions significantly
(p
≤
0.05) decreased during the second brewing, both at 70
◦
C (approx. 18%) and 100
◦
C
(approx. 16%) in compared to single infusions (Figure 7). A similar downward trend was
found in the total polyphenol content, with the much higher losses, reaching almost 40%,
both at 70
◦
C and 100
◦
C (Figure 6). Analogous trends have been confirmed in several
studies by other authors [16,49,65].
Bravo et al. (2007) [
25
] in triple-brewed Yerba Mate samples showed very low an-
tioxidant activity, i.e., from 1.56
±
0.24 up to 1.71
±
0.12
µ
M TEAC/g d.m. in infusions
and from 1.48
±
0.15 up to 1.81
±
0.08
µ
M TEAC/g d.m. in extracts of various commer-
cial Yerba Mate products. Dmowski and Post (2018) [
49
] showed that each of the three
consecutive infusions significantly reduced the total polyphenol content and reduced (al-
though not statistically significant) the antioxidant capacity of the infusions (measured
using DPPH radicals). Also Colpo et al. (2016) [
65
] showed that the concentration of
phenolic compounds significantly decreased with subsequent brewing, and the antioxidant
activity (measured by the ability of the extracts to chelate Fe
2+
iron, remove DPPH and
NO radicals) decreased, but remained at a significant level. Considering that Yerba Mate is
usually consumed in the form of multiple brewed infusions [
16
], the tendency to maintain
significant antioxidant activity, even in fairly diluted infusions, is extremely important from
the point of view of the pro-health potential, in particular the antioxidant activity, of this
drink [65].
According to the literature, both the content of bioactive ingredients, including
polyphenols, and the antioxidant potential of Yerba Mate, fall within very wide limits. The
differences result from, among others: various brewing methods and conditions (including
Molecules 2024,29, 2590 20 of 27
temperature, time or number of infusions) [
16
,
45
,
48
,
49
], botanical part of the plant, com-
position and degree of fragmentation of commercial available mixtures [
6
,
25
–
27
,
44
,
46
,
47
],
from cultivar and morphotype [
17
,
20
,
43
], age of leaves, production technology and de-
gree of Yerba Mate processing [
3
,
20
,
21
,
42
,
45
,
46
,
48
], also from origin [
23
] or plant growth
conditions, soil type, climate and cultivation system [39,42].
The conducted research showed a significant (p
≤
0.05), positive relationship between
the content of total polyphenols and antioxidant activity, both in infusions obtained as a
result of a single (R
2
= 0.9787 a) and double (R
2
= 0.992) of brewing the tested samples of
Yerba Mate, which is presented in Figure 8.
Figure 8. Relation between the content of total polyphenols (mg GAE/g d.m.) and antioxidant activity
(µM TEAC/g d.m.) in Yerba Mate infusions obtained as a result of single (a) and double (b) brewing.
Bassani et al. (2013) [
48
] showed a relationship between the content of flavonoids
and the antioxidant activity measured with the use of DPPH radicals (R
2
= 0.9046 to
R
2
= 0.9972). Deladino et al. (2013) [
75
] found a correlation between chlorogenic acid
vs.