Content uploaded by Grzegorz Zaguła
Author content
All content in this area was uploaded by Grzegorz Zaguła on Jan 02, 2017
Content may be subject to copyright.
BALTIC FORESTRY
230
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
Introduction
In the olden days, the sap of spring trees was fre-
quently used in traditional medicine in forested areas of
northern hemisphere. In Europe, the main source of tree
sap was birches: Betula pendula Roth. (silver birch), Bet-
ula pubescens Ehrh. (downy birch) (Jones 2011, Svanberg
et al. 2012). Birch sap was known as valuable antidote
against scurvy, kidney, stomach and liver diseases, for
gall stones, skin diseases and as a nutritional drink. It was
used also in veterinary and as a cosmetic product – hair
conditioner. Nowadays, the birch sap has become more
and more popular as natural probiotic, after fermenta-
tion (Semjonovs et al. 2014). Its tapping is carried out
in Russia, Belarus, Ukraine, Latvia, Estonia and also in
Korea, Japan and China at large scales (Svanberg et al.
2012, Kūka et al. 2013). The best time for the birch sap
harvesting depends on geographical location, climate and
weather course. In central Europe it is late March and ear-
ly April, with later start toward the north. Generally, birch
tree can secrete sap from two to four weeks and its yield
depends on birch species (Kallio and Ahtonen 1989, Jiang
et al. 2001, Peev et al. 2010). Birch sap is a transparent
The Bioactive and Mineral Compounds in Birch Sap
Collected in Different Types of Habitats
DOROTA GRABEK-LEJKO1*, IDALIA KASPRZYK2, GRZEGORZ ZAGUŁA3,
AND CZESŁAW PUCHALSKI3
1University of Rzeszów, Department of Biotechnology and Microbiology, Zelwerowicza 4 St., 35-601 Rzeszów,
Poland
2University of Rzeszów, Department of Environmental Biology, Zelwerowicza 4 St. 35-601 Rzeszów, Poland
3University of Rzeszów, Department of Bioenergy Technology, Zelwerowicza 4 St. 35-601 Rzeszów, Poland
*Correspondence author: dorobek@o2.pl; phone: 0048 17 7855438.
Grabek-Lejko, D.*, Kasprzyk, I., Zaguła, G. and Puchalski, Cz. 2017. The Bioactive and Mineral Compounds in
Birch Sap Collected in Different Types of Habitats. Baltic Fo restry 23(1).
Abstract
Birch sap is used as a traditional drink and in traditional medicine in many countries in the northern hemisphere. However,
there are scarce data on the antioxidant properties, nutrients and the mineral content of birch saps. In this study, the above-mentioned
properties were analyzed in two different birch species Betula pendula Roth (silver birch) and Betula pubescens Ehrh. (downy birch)
in various areas (suburban, trafc and industrial). The current study evidenced signicant differences between the antioxidant, nutri-
tion and mineral content depending on the type of habitat, not on species. It was shown that higher antioxidant properties, sugar and
protein content were detected for silver birch sap from industrial area, which may be due to the response of plants to environmental
stress. Moreover, heavy metals presenting in soil were not detected or detected at low concentrations in the sap. Birch sap can be
used as a valuable natural beverage, which is especially important nowadays, when there is a pressure to minimize the use synthetic
and articial food ingredients.
Keywords: Antioxidants, Betula pendula, Betula pubescens, birch sap, minerals, nutrients, heavy metals.
or a slightly opalescent uid. It tastes similar to water and
is slightly sweetish (Peev et al. 2010). It contains many
bioactive compounds. The total amino acid concentration
ranges from 100–500 mg.L-1. Among free amino acids
glutamine, citrulline, glutamic acid, isoleucine, valine and
asparagine are the most often detected. They represent
92–96 % of the total amino acid content. Their concentra-
tions change during ow season (Kallio et al. 1985, Kallio
and Ahtonen 1989). In Japan, the maximum of the total
amino acid content of silver birch was above 50 mg.L-1
and reached this value at the end of the ow season (Jiang
et al. 2001, Jeong et al. 2012).
The total sugar content oscillates from 1% in Finland
and 2.5-2.6% in Poland. The dominant carbohydrates are
glucose and fructose. Their concentrations range between
2-5 g L -1 in equal proportions each of them representing
over 80% of total sugar. The content of sucrose is three to
ten time less than fructose or glucose content (Kallio et al.
1985, Kallio and Ahtonen 1987, Kūka et al. 2013, Łuczaj
et al. 2014).
Birch sap also contains valuable minerals. Calcium
and potassium occur in the highest concentrations. In Lat-
vian silver birch sap, the mean content of Ca ranged from
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
231
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
41 to 150 mg L-1 and K from 41 to 142 mg L-1 (Kūka et
al. 2013, Vincēviča-Gaile 2014). In many samples, Zn,
Mg, Mn, Cu, Cd, Fe and Na were detected (Jeong et al.
2012, Kūka et al. 2013, Vincēviča-Gaile 2014, Bilek et al.
2015a). In Polish samples, the contents of these minerals
were lower and the variability between individual trees
was much higher (Bilek et al. 2015a).
The problem of the chemical composition of tree sap
was frequently investigated in the 80s and 90s of the 20th
century. Much less attention has been paid to the bioactive
properties (Klinger et al. 1989). Lee et al. (2009) observed
a weak inhibitory effect on microbial growth, as well as
phagocytosis-inuencing, antiphlogistic and antipyretic
activities. The question of impact of the type of habitat
on the nutrient and mineral content was also very rarely
investigated (Vincēviča-Gaile 2014). Due to the increas-
ing use of birch sap, an exact knowledge of its properties
seems to be justied.
This research was aimed to evaluate antioxidant
properties, nutrient and mineral content of fresh sap of
two birch species B. pendula Roth. and B. pubescens
Ehrh. The goal of this study was to verify the prelimi-
nary hypothesis that the type of habitats (like soils with
heavy metals content) and birch species affect the above-
mentioned properties. The purpose of this study was also
to evaluate whether birch sap, so popular lately, can be a
valuable natural beverage.
Materials and Methods
Sample collection
The study was conducted in three sites that differed
in terms of the type of habitats: industrial area (steel mill,
Ostrowiec), high trafc area (Rzeszów) and suburban area
(Zalesie). Birch sap was collected from 4-5 randomly
chosen individuals of B. pendula and B. pubescens. Soil
samples were taken from one soil layer (0-20 cm) close the
trees from which sap were harvested. The sampling was
carried out at the end of March and the beginning of April
2015. At a height of 30 cm of the trunk, small 8 mm diam-
eter holes were drilled, then, a plastic pipe (15 cm long and
8 mm in diameter) was put into the hole. Underneath each
pipe, a sterile plastic tube was placed (volume of 50 mL).
The tubes were closed after collecting the sap and then l-
tered with 0.45 µm lters and frozen at -80 oC till analysis.
Chemical analysis
Antioxidant activities
Antioxidant activities were determined by two meth-
ods: FRAP and ABTS. For ABTS determination, method
of Re et al. (1996) was used. The results were expressed
as µmoles of Trolox per 1L of birch sap.
A manual assay of ferric reducing/antioxidant power
(FRAP) was used based upon the methodology of Benzie
and Strain (1999). A standard Trolox solution was used
for the calibration curve and the results were expressed as
µmoles of Trolox equivalent per 1L of birch sap.
Total polyphenol content was measured using the
Folin-Ciocalteu colorimetric method (Singleton and Ros-
si 1965). The results were expressed as mg of gallic acid
equivalents (GAE) per 1L of birch sap.
Microbiological assay with Enterococcus hirae
ATCC™ 8043 was used for folic acid determination ac-
cording to Difco™ & BBL™ Manual, 2nd Edition. E. hi-
rae was added to the medium used for this analysis (Folic
Acid Assay Medium - FAAM). E. hirae cannot grow on
FAAM without addition of external folic acid. The addi-
tion of folic acid in specied increasing concentrations
gives a growth response that can be measured turbidi-
metrically. Briey, night culture of E. hirae (previously
washed tree times in order to remove all residues of folic
acid from the medium) was used for inoculation of FAAM
medium with increasing concentrations of folic acid (0-10
ng/10 ml for calibration curve) or with different concen-
trations of analyzed birch saps. After 24 h incubation at
37 oC, bacterial growth was determined turbidimetrically
at OD 660 nm. Concentration of folic acid was calculated
from the calibration curve.
Nutrients determination
Sugars (glucose, fructose, sucrose) were determined
reectometrically according to the appropriate manuals
of Merck Reectoquant®. Results were expressed as g of
sugar per 1L of birch sap. Proteins were determined ac-
cording to the Lowry method (Lowry et al. 1951). For the
calibration curve, bovine serum albumin was used. Re-
sults were expressed as mg of protein in 1L of birch sap.
Total calories were calculated as a sum of calories from
sugars and proteins, where proteins possess 4 kcal g-1 and
sugars 3.8 kcal g-1.
Minerals detection
Mineral elements were analyzed by an inducted cou-
pled plasma optical emission spectrometer (ICP-OES),
ThermoiCAP Dual 6500 (USA). Each time, the dilution
of 1 mL volume of birch sap lled up the tube to 10 mL
with deionised water was performed. For each of the ele-
ments, 3-point calibration curves were created. Selection
of appropriate length measuring line has been validated
by method of standard additions in amount of 10 ppb to
100 ppb give the recovery on selected lines above 98.5%
for each of the elements.
Soil samples were heated at 100 oC till constant
weight. Then 0.2 g of soil samples were lled up with
6 mL of 40 % HCl + 2 mL of HNO3. Microwave miner-
alization procedure with Milstone Ethos One Microwave
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
232
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
Digestion System was used. After mineralization, samples
were lled up to 50 mL with demi water and used for min-
eral elements detection. Mineral elements were analyzed
with the aid of inducted coupled plasma optical emission
spectrometer (ICP-OES), ThermoiCAP Dual 6500 (USA).
Results were expressed as g per kg of dry soil sample.
Data analysis
The comparison of the means of the analyzed pa-
rameters of two species was tested by the parametric Stu-
dent’s T-test. ANOVA or Kruskall-Wallis test (nonpara-
metric) with appropriate post-hoc tests (Tukeya or Dunna
respectively) were applied to compare the means from
three sites. The type of statistical test was chosen after
analysis of the data distribution using Shapiro-Wilk test.
The statistical hypotheses were tested with α ≤ 0.05.
Results
Antioxidant activities
The in vitro antioxidant effect of the investigated
extracts was evaluated by the ABTS assay as a capabil-
ity of ABTS∙+ - compound possessing and antiradical ac-
tivity to scavenge free radicals and by the FRAP assay
as a capability of antioxidants to reduce Fe(III) to Fe(II)
(Liaudanskas et al. 2014). The results obtained from the
study of the antioxidant properties are given in Table 1.
It was shown that birch saps from Ostrowiec contained
the highest levels of antioxidants in comparison with saps
from Zalesie and Rzeszow. Antioxidant activities were
higher by about 45-80% for the FRAP and 54-64% for the
ABTS methods. Analysis of the variance allowed us to
prove that there are statistically signicant differences in
antioxidant activities between different localities of silver
birch trees. Antioxidant properties detected by FRAP and
ABTS methods are different between saps from the indus-
trial area (Ostrowiec) and the trafc area (Rzeszow), and
also between the industrial region (Ostrowiec) and the
suburban region (Zalesie). There are slightly but not sig-
nicant differences in antioxidant activities between saps
from Zalesie and Rzeszów (Table 1). Antioxidant proper-
ties were higher for silver birch sap, but the differences
were not statistically signicant.
Phenolic compounds
The total phenolic content of the birch saps was
estimated by using the Folin-Ciocalteu reagent. Table 1
summarizes that average concentration of total pheno-
lic compounds in birch saps varied widely ranging from
35.41 mg GAE.L-1 for silver birch from Zalesie to 55.15
mg GAE.L-1 for silver birch sap from Ostrowiec. When
comparing the concentration of phenolic compounds de-
pending on the locality, where sap was taken, there have
been revealed statistically signicant differences between
the industrial region – Ostrowiec and the suburban re-
gion – Zalesie, which are in correlation with antioxidant
activities (Table 1). Authors did not detect statistically
signicant differences in phenolic compounds concentra-
tion between the birch species.
Folic acid concentration
Folic acid is one of the vitamins, which also possess
antioxidant activities. The highest values were obtained
from silver birch sap from Ostrowiec, and values subse-
quently decreased in the following order: silver birch –
Zalesie < silver birch – Rzeszow < downy birch (Table 1).
Nutrients
Among sugars, which were analyzed, the lowest glu-
cose and fructose concentrations were detected for downy
birch sap and the highest ones for silver birch sap from Os-
trowiec. Differences between glucose concentrations are
from 36% to 55%, and for fructose concentrations from
24% to 60%. The concentration of sucrose is also the low-
est for the downy birch sap. Saps from silver birch trees lo-
calized in Rzeszow and Ostrowiec were the same in terms
of the sucrose content and the highest sucrose concen-
tration was detected for sap from Zalesie. However, it is
worth to state that the standard deviation in these samples
is very high. On the other hand, the highest protein con-
centration was detected for silver birch sap but differences
between the protein concentrations are quite low, around
6 – 12% (Table 1). Comparing the saps of the two birch
species, it can be stated that statistically signicant dif-
ferences were detected only in the content of glucose and
sucrose (Student’s T-test; p = 0.0014; Table 1). Birch sap is
a low-calorie diet beverage. Calorie content of silver birch
sap from suburban and industrial sites was in the range
from 29.95 to 47.68 kcal L-1, respectively, and the average
calorie content for downy birch sap is 39.45 kcal.L-1.
Minerals in the birch sap
Of all the investigated minerals, calcium presented
the highest content especially in the trafc area, where its
concentration was signicantly higher than at the other
sites (above 75%). In the industrial and suburban areas, its
concentrations were similar oscillating around 165 mg per
litre. Also, a quite high potassium content was noted. Its
concentrations ranged on average from 100 to 180 mg L-1.
Authors stated signicant differences in the potassium
concentration at sites with the lowest content in the sub-
urban area. Concentrations of manganese and zinc in sil-
ver birch sap were similar and on average ranged from 2
to 4 mg L-1. It was stated that concentrations of certain
microelements depended on the habitats. Mean concentra-
tion of sodium was the highest in the industrial area, and
of iron and phosphorus in the trafc one. Copper concen-
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
233
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
trations differed at each of the habitats (Table 2). Silver
and downy birches differed in phosphorus and iron con-
tent, which were higher for the latter species (Student’s
T-test; 0.046, p = 0.0049 respectively; Table 2). In downy
birch sap, sodium was not detected. Concentrations of
cadmium, chromium, lead, nickel and aluminium were
below their levels of determination.
Species Sites
FRAP
Trolox
(µmoles.L-1)
ABTS
Trolox (µmoles.L-1)
Phenolic
compounds
Gallic acid (mg.L-1)
Folic acid
(µg.L-1)
Mean ± SD
Z 41.10±18.89a313.03±67.95a35.41±19.82a5.79±2.49ab
B. pendula Ra49.45±8.38a305.92±60.18a40.39±9.91ab 4.39±1.04a
O 71.95±15.51b481.36±73.83b55.15±15.89b7.10±2.43b
B. pubescens Rb40.00±14.62 294.32±46.44 38.13±7.26 3.93±1.83
Species Sites Glucose (g.L-1) Fructose (g.L-1) Sucrose (g.L-1) Proteins (g.L-1)
Mean ± SD
Z 5.23±3.47 5.36±2.95 0.63±0.71 0.272±0.105
B. pendula Ra4.72±2.09 4.82±1.82 0.28±0.12 0.272±0.117
O 5.38±1.11 6.23±3.11 0.28±0.19 0.287±0.130
B. pubescens Rb3.46±0.61 3.88±0.38 0.014±0.023* 0.307±0.073
Species Sites Ca (mg.L-1) K (mg.L-1) Mg (mg.L-1)
Mean ± SD
Z 169.270±68.987a107.366±58.401a18.635±11.538a
B. pendula Ra212.767±16.238b174.569±53.820b25.307±4.6107a
O 162.587±29.356a179.136±60.641b31.196±12.646b
B. pubescens Rb217.874±67.501 149.087±43.746 24.9627±6.642
Species Sites Zn (mg.L-1) P (mg.L-1) Na (mg.L-1)
Mean ± SD
Z 2.967±0.995a 7.008±2.054a0.266±0.359a
B. pendula Ra4.115±1.72a 23.522±7.447b 0.158±0.279a
O 3.243±0.775 a 19.916±6.124b 1.974±1.689b
B. pubescens Rb4.498±1.608 a 34.992±8.44* nd
Species Sites Cu (µg.L-1) Fe (mg.L-1) Mn (mg.L-1)
Mean ± SD
Z 0.048±0.019a0.198±0.042a 2.955±2.363
B. pendula Ra0.099±0.015b0.249±0.049b4.092±6.977
O 0.138±0.021c0.203±0.034a1.929±1.910
B. pubescens Rb0.089±0.020 0.304±0.089* 7.923±3.61
Table 2. Mean concentrations of chosen minerals for Zalesie (Z), Rzeszów (Ra – B. pendula ,Rb – B. pubescens) and Ostrowiec (O)
Notes: (a, b and c mark statistically signicant differences between the sites according to ANOVA or Kruskal-Wallis tests and post
hoc tests, α≤ 0.05;
* the statistically signicant differences between species according to Student’s t-test (with α ≤ 0.05).
Table 1. Mean concentrations of chosen parameters of antioxidants and nutrients for Zalesie (Z), Rzeszów (Ra – B. pendula ,Rb – B. pubescens)
and Ostrowiec (O)
Notes: (a, b and c mark statistically signicant differences between the sites according to ANOVA or Kruskal-Wallis tests and post
hoc tests, α ≤ 0.05;
* the differences between species according to Student’s t-test with α ≤ 0.05;
nd stands for “not detected”.
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
234
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
Minerals in soil
It can be stated that soil samples from Ostrowiec dif-
fers from soil samples from other places containing high-
er concentrations of some elements. They are richer in Ca,
Zn, P, Ca, Cu, Fe and Na (Table 3). Among heavy metals,
Pb, Cd and Cr concentrations are higher in soil from Os-
trowiec too. Ni and Al concentrations are similar in all
types of soils varying from 0.01 to 0.024 and from 4.1 to
6.38 g kg- 1, respectively. Pb concentration is 5-11 times
higher than in soils from the trafc area, and more than
30 times higher than in soil from the suburban area. Cd
concentration is 20 times higher than in suburban area and
one soil from the trafc area was around 10 times higher
than in the soil from other trafc area. Cr concentration
is 1.5 times higher than in the trafc area, and 3.5 times
higher than in the suburban area. Heavy metals (HM) like
Ni, Pb, Cd, Cr, Al and Zn were determined in all analysed
soil samples. But it can be stated that in most cases HM
concentrations in soil from the industrial area (Ostrowiec)
were higher than from ones of the other localities.
Discussion
Nowadays, there is a tremendous resurgence in the
interest and use of natural healthy products, foods, me-
dicinal plants etc. According to the World Health Orga-
nization (WHO), as many as 80 % of the world’s people
depend on traditional medicine for their primary health-
care needs (WHO 1993, Škrovánková et al. 2012). The
number of consumers interested in healthy food continues
to grow, which corresponds with an increasing number
of health-food and specialty stores, in which different
healthy products are available (Briskin 2000). Birch sap
is an example of such a product that is becoming more and
more popular in Poland. It is available in special healthy
food stores but lately also in supermarkets, the advertising
campaign was extended in the popular media, and more-
over, there are more and more distributors and producers
of this product.
The present study quantitatively determined the con-
centration of bioactive and nutrition compounds as well
as mineral substances in saps obtained from two species
of birch trees, B. pendula (silver birch) and B. pubescens
(downy birch). We have attempted to nd out if there are
any differences in these parameters depending on the
birch species and localities (between the trafc, suburban
and industrial areas).
According to these studies, authors can easily detect
that antioxidant properties of saps from the industrial re-
gion are signicantly higher than those from the trafc
and suburban areas both for FRAP and ABTS methods,
respectively. It is known that different stress factors, en-
Sites Ca (g.kg-1) K (g.kg-1) Mg (g.kg-1) Zn (g.kg-1) P (g.kg-1)
Mean ± SD
Z 1.234±0.014a0.801±0.014a1.318±0.014a0.026±0.001a0.246±0.003a
Ra4.842±0.066b3.609±0.029b3.418±0.014b0.0797±0.000b0.607±0.014b
O 12.284±0.014c1.220±0.014c2.635±0.043c0.806±0.014c8.091±0.052c
Rb1.600±0.054d2.309±0.052d2.510±0.025d0.056±0.001d0.632±0.014b
Sites Na (g.kg-1) Cu (g.kg-1) Fe (g.kg-1) Mn (g.kg-1) S (g.kg-1)
Mean ± SD
Z 0 0.007±0.000a7.404±0.052a0.2696±0.001a0.059±0.001a
Ra0.097±0.003a0.023±0.003b17.229±0.076b0.382±0.014b0.287±0.001b
O 0.088±0.004b0.063±0.001c22.463±0.413c0.479±0.009c0.812±0.014c
Rb0.041±0.004c0.035±0.001d13.238±0.090d0.338±0.013d0.158±0.001d
Sites Ni (g.kg-1) Pb (g.kg-1) Cd (g.kg-1) Cr (g.kg-1) Al (g.kg-1)
Mean ± SD
Z 0.010±0.000a0.004±0.000a0.00009±0.000a0.015±0.001a4.100±0.025a
Ra0.024±0.001b0.029±0.001b0.0002±0.052b0.037±0.000b6.375±0.025b
O 0.016±0.001c0.138±0.001c0.00193±0.000c0.053±0.001c5.350±0.025c
Rb0.018±0001c0.012±0.000d0.00008±0.000a0.030±0.001d6.300±0.05b
Table 3. Mean concentration of chosen minerals in soil from Zalesie (Z), Rzeszów (Ra – B. pendula ,Rb – B. pubescens) and Ostrowiec (O)
Notes: (a, b and c mark statistically signicant differences between the sites according to ANOVA or Kruskal-Wallis tests and post
hoc tests with α ≤ 0.05;
* the statistically signicant differences between species according to Student’s t-test with α ≤ 0.05.
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
235
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
vironmental pollution etc. causing oxidative stress are
connected with reactive oxygen species (ROS) formation.
Living organisms like plants possess several antioxidative
defense systems to scavenge toxic-free radicals in order
to protect themselves from the oxidant stress (Zeneli et al.
2013). It was reported that the tolerance of plants for oxi-
dative stressing conditions may be explained by the en-
hanced activity of antioxidative enzymes preventing cell
and tissue damage (Shi et al. 2006). Higher antioxidant
properties of saps from the industrial region may have re-
ected higher environmental stressing conditions in com-
parison with saps from other sites (Krishnaveni 2013).
Moreover, it was reported that antioxidant properties may
depend on the species or even individuals. Some plants,
growing near cement factory and exposed to cement dust
pollution, exhibited higher antioxidant properties than
control plants, but other species have a lower defense
system against cement dust pollution and lower antioxi-
dant potential than appropriate control plants (Mutlu et al.
2009). Therefore, higher antioxidant capacities of birch
sap from the industrial area can be explained as a high tol-
erance of birch to environmental pollution, manifested by
an increased content of antioxidants protecting the plant
against different environmental stresses. Therefore, in
theory, variations in antioxidant responses throughout the
life cycle occur, making the plant more or less susceptible
to seasonal variations in diverse environmental stressors.
Variations in the levels of antioxidants may also oc-
cur during the aging of the plant (Ferreira and Domingos
2012). The authors chose the trees randomly so this can
be an explanation for large differences in maximum and
minimum values of these parameters at one location. It is
difcult to compare results obtained in our study to oth-
ers because there is little information about antioxidants
in birch saps or researchers used different methods to es-
timate the antioxidant capacity with different standards,
incubation time and concentrations. Kūka et al. (2013) de-
tected the antioxidant concentration of Latvian birch saps
at 0.35 mg L-1 of quercetin equivalent.
It is known that the concentrations of phenolic com-
pounds in many plants are strictly correlated with their an-
tioxidant properties (Piluzza and Bullitta 2011, Jeong et al.
2013). Observed differences between the phenolic content
in analyzed saps showed that phenolic compounds were
important antioxidant components. Concentration of folic
acid along with antioxidant properties (Joshi et al. 2001)
is much higher in saps from the industrial region, which
means that in all methods used for antioxidant detection,
authors observed statistically signicant difference in their
concentration in saps from the industrial region compared
with saps from the trafc and suburban areas.
The formation and level of antioxidants may be sea-
sonality marked in response to changes in the environ-
mental conditions. This is plausible because the seasonal-
ity is reected in solar irradiation, photoperiod, tempera-
ture, relative humidity and actions of other meteorologi-
cal factors. Some authors also observed that antioxidants
concentration can be a response to the meteorological
characteristics of each season of the year (Ferreira and
Domingos 2012). The differences in the antioxidant con-
centration between localities can be explained by some
differences in the course of weather in 2015 during ow
season in different regions of Poland as well as the micro-
climate (Meteoblue Weather 2016).
Analyzing the sugar concentration, authors observed
that the saps contained mainly fructose and glucose, how-
ever, sucrose was also found in lower amounts. Sugar pro-
portions were similar to those found in northern Europe
and in Poland (Kūka et al. 2013, Łuczaj et al. 2014). Sug-
ar, protein and mineral concentrations obtained by other
authors were shown in Table 4.
These results are also similar to those detected by
Korean researchers for white birch sap (Jeong et al.
2012). They detected that its sugar content varied from
3.6 to 4.3 g L-1 and from 4.9 to 6.6 g L-1 for glucose and
fructose, respectively. In results presented in this paper,
glucose concentration was slightly higher for silver birch
sap from Zalesie and Ostrowiec. Polish silver birch sap
contains more glucose and fructose than birch sap pro-
duced in Lithuania and in Finland (Kūka et al. 2013). Glu-
cose and fructose concentrations in downy birch sap is
approximately 30 % lower than in saps from Polish and
Table 4. Concentration of sugars, proteins and selected minerals in birch saps
Parameter Object Analytical results Reference
Glucose (g·L-1)
B. pendula 3.6 to 4.3 Jeong et al. (2012)
B. pendula 9.3±3.9 Łuczaj et al. (2014)
B. pendula 3.55-4.96 Bilek et al. (2015b)
B. pendula 4.46±0.04 Kûka et al. (2013)
B. pubescens 1.99-3.016 Bilek et al. (2015b)
B. pubescens 9.6±2.9 Łuczaj et al. (2014)
B. platyphylla var. japonica 2.5 Jeong et al. (2013)
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
236
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
Fructose (g·L-1)
B. pendula 4.9 to 6.6 Jeong et al. (2012)
B. pendula 5.39±0.05 Kûka et al. (2013)
B. pendula 12.1±4.9 Łuczaj et al. (2014)
B. pendula 4.03-4.77 Bilek et al. (2015b)
B. pubescens 13.5±3.3 Łuczaj et al. (2014)
B. pubescens 1.83-2.77 Bilek et al. (2015b)
B. platyphylla var. japonica 3.3 Jeong et al. (2013)
Sucrose (g·L-1)
B. pendula 0.07 Jeong et al. (2013)
B. pendula 0-1.509 Bilek et al. (2015b)
B. pendula 0.58±0.01 Kûka et al. (2013)
B. pendula 3.2±2.4 Łuczaj et al. (2014)
B. pubescens 3.1±1.4 Łuczaj et al. (2014)
Protein (mg·L-1)
B. pendula 127±2 Kûka et al. (2013)
B. platyphylla var. japonica 15-35 Jiang et al. (2001)
B. verrucosa 15-28 Jiang et al. (2001)
Ca (mg.L-1)
B. pendula 41.0-53.3 Kûka et al. (2013)
B.pendula 5.52 -17.28 Bilek et al. (2015)
B. pubescens 15.12±4.74 Bilek et al. (2015)
B. platyphylla var. japonica 25.82±0.12 Jeong et al. (2013)
Betula sp. 42 – 150 Vincēviča-Gaile (2014)
Cu (mg.L-1)
B. pendula 0.15-0.39 Bilek et al. (2015)
B. pendula 0-0.04 Kûka et al. (2013)
B. pubescens 0.48±0.42 Bilek et al. (2015)
B. platyphylla var. japonica 0.82±0.10 Jeong et al. (2013)
Betula sp. 0.02-0.03 Vincēviča-Gaile (2014)
Fe (mg.L-1)
B. pendula 0-0.1 Kûka et al. (2013)
B. platyphylla var. japonica 0.61±0.09 Jeong et al. (2013)
Betula sp. 0.05-0.11 Vincēviča-Gaile (2014)
K (mg.L-1)
B. pendula 10.56-23.76 Bilek et al. (2015)
B. pendula 41.1-66.4 Kûka et al. (2013)
B. pubescens 18.08±18.85 Bilek et al. (2015)
B. platyphylla var. japonica 30.10±4.81 eong et al. (2013)
Betula sp. 54 – 142 Vincēviča-Gaile (2014)
Mg (mg.L-1)
B. pendula 4.42-14.36 Bilek et al. (2015)
B. pubescens 13.82±5.55 Bilek et al. (2015)
B. platyphylla var. japonica 11.90±0.15 Jeong et al. (2013)
Betula sp. 0 Vincēviča-Gaile (2014)
Mn (mg.L-1)
B. pendula 0.5-0.52 Kûka et al. (2013)
B. platyphylla var. japonica 2.36±0.02 Jeong et al. (2013)
Betula sp. 0.11-6.16 Vincēviča-Gaile (2014)
Na (mg.L-1)
B. pendula 0.56-0.59 Bilek et al. (2015)
B. pubescens 0.55±0.62 Bilek et al. (2015)
B. platyphylla var. japonica 7.51±0.36 Jeong et al. (2013)
Betula sp.0Vincēviča-Gaile (2014)
Ni (mg.L-1)B. pendula 0-0.03 Kûka et al. (2013)
Betula sp. 0.02-0.16 Vincēviča-Gaile (2014)
Zn (mg.L-1)
B. pendula 0.88-1.85 Bilek et al. (2015)
B. pubescens 1.29±0.17 Bilek et al. (2015)
B. platyphylla var. japonica 3.82±0.47 Jeong et al. (2013)
Betula sp. 0.9-4.96 Vincēviča-Gaile (2014)
P (mg.L-1)Betula sp.3 - 41 Vincēviča-Gaile (2014)
S (mg.L-1)Betula sp. 5 – 12 Vincēviča-Gaile (2014)
Cr (mg.L-1)Betula sp. 0.02 Vincēviča-Gaile (2014)
Co (mg.L-1)Betula sp. 0.05 Vincēviča-Gaile (2014)
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
237
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
Latvian silver birch (Table 4). In contrast to these results,
Łuczaj et al. (2014) did not detect signicant differences
in sugar concentrations between silver birch and downy
birch saps. It can be explained by the fact that the amount
of sugars in tree saps depends on many parameters. The
tree sap sugar concentrations can be affected by the time
of day, stage of ow cycle (beginning/end of the ow),
tree size, age and soil fertility, basal area of ray issue and
weather conditions in the year, or even shifts in gas con-
tents in the atmosphere.
Sucrose concentration in white birch sap detected by
Jeong et al. (2013) was 0.07 g L-1. For these sap, sucrose
concentration was at least four times higher than for sil-
ver birch sap localized in Rzeszow and Ostrowiec, and al-
most ten times higher than for sap from Zalesie. However,
authors observed a great variability between individuals.
On the other hand, sucrose concentration for downy birch
was ve times lower than those detected by Jeong et al.
(2013) (Table 4). For Latvian birch, the sucrose concen-
tration was about 0.58 g L-1, which is twice higher than for
B. pendula from the industrial and trafc areas and slight-
ly lower – around 10 % – than for sap from suburban area
(Kūka et al. 2013). Statistically signicant differences in
glucose and sucrose concentrations between species are
attributed to species factors.
Protein concentrations in our saps are at least twice
higher than those detected for Lithuanian birch saps
(Kūka et al. 2013). Japanese researchers also detected a
very low protein concentration for saps from white and
silver birches at a level of 15-35 mg L-1 depending on the
harvesting time (Jiang et al. 2001) (Table 4). As Łuczaj et
al. (2014) said, relatively high values of sugars in Polish
saps suggest that Poland may be a suitable place for de-
veloping the tree sugar industry.
Birch sap contains over a dozen minerals (Harju and
Hylden 1990). In many scientic works, the authors in-
dicated that among minerals cooper reached the lowest
concentrations, whereas calcium and potassium the high-
est ones (Kūka et al. 2013, Vincēviča-Gaile 2014, Bilek
et al. 2015a) (Table 4). Harju and Hylden (1990) noted
the concentrations of manganese, phosphorus and zinc ex-
ceeded 1 mg L-1. Presented results are in accordance with
them, however, we observed the great variability among
individual trees as well as the sites. It concerned mainly
sodium, what was also detected by Bilek et al. (2015a).
Bilek et al. (2015a) compared the mineral com-
pounds of the sap with the recommended daily allowance
for adults. According to their results, one liter of silver
birch sap covers up to 40 % of daily copper requirements,
zinc up to 17 %, calcium up to 2%, magnesium up to
3-4 % and sodium up to 0.04 %. The authors obtained
different results such as about 11 %, 30 %, 18 %, 8 % and
0.05 %, respectively.
The high variability could be affected by environmen-
tal and anthropogenic factors. In polluted areas, concen-
trations of certain minerals in plants increases (Vincēviča-
Gaile, 2014). The authors noted that the highest iron and
phosphorus concentrations were in the sap harvested from
the trafc and industrial sites. High concentrations of
heavy metals (HM) may negatively affect living organ-
isms, the ecosystems and human health. HMs presented
in soils may be transported through the food chain to the
human body and have a signicant toxic effect to people
(Butkus and Baltrėnaitė 2007, Yan et al. 2012). Harju and
Hylden (1990) found increased concentrations of Pb, Zn,
Ag and Cd in birch sap collected in polymetallic damps in
south western Finland. Generally, in study areas the con-
centration of minerals was higher in soil collected near
steel mill (Ostrowiec) and the lowest ones in soil from
suburban area (Zalesie) but authors did not detect any
connection between mineral concentrations in soils and
in saps. Among HMs only a few ones were detected in
saps. These results conrm that transport of many HMs
from soil to plant is not very active (Kandziora-Ciupa et
al. 2015). Lead is characterized by poor bioavailability
and therefore it was not found in saps. Also very toxic
cadmium was not transported from soils to saps. Copper
and zinc as trace elements are essential for proper metabo-
lism, growth and development of plants, but in the high-
est concentrations are toxic (Wierzbicka 2015). Authors
noted that in soil these elements were presented but their
concentrations in the saps were low. These results are very
important for potential consumer because, regardless of
the heavy metal soil contamination, birch sap is resistant
to toxic minerals.
Conclusion
Taking into account its chemical composition, birch
sap should be considered as a low-calorie diet supple-
ment, a good substitute for water: medium and high min-
eralized, which should contain at least 150 mg per litre of
macronutrients like Ca, K and Mg. In respect of miner-
als, antioxidant and nutrient properties the downy birch
sap is just as valuable as the sap of silver birch. Varia-
tion in chemical compounds may be caused by the type
of habitats and inter-individual variability. It seems that
birch sap is quite resistant to heavy metals present in soil.
Heavy metals concentrations in soil, as well as other en-
vironmental stresses such as pollutants of trafc origin
may cause higher antioxidant activity of birch sap. When
preparing to sap harvesting, the potential soil and air pol-
lution in sampling site should be taken into account.
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
238
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
Acknowledgement
The work was partly supported by Cross-border
Cooperation Programme Poland-Belarus-Ukraine 2007-
2013, IPBU.03.01.00-18-452/11-00 and by the Polish
Ministry of Science and Higher Education (No 3020/
PBU/0755/11/13/2014/2). Responsibility for the content
of this publication lies solely with the authors and can-
not,underanycircumstances,beconsideredtoreectthe
position of the European Union in any way.
References
Benzie, I.F. and Strain, J. 1999. Ferric reducting antioxidant power
assay: direct measure of total antioxidant activity of biological
uids and modied version of simultaneous measurement of
total antioxidant power and ascorbic acid concentration. Meth-
ods in Enzymology 299: 15-27.
Bilek, M., Stawarczyk, K., Łuczaj, L. and Cieslik, E. 2015a.
Zawartość wybranych składników mineralnych i anionów
nieorganicznych w sokach drzewnych z terenu Podkarpacia
[Content of selected minerals and inorganic anions in tree saps
from Podkarpacie region]. Żywność. Nauka. Technologia.
Jakość 3 (100): 138-147 (in Polish).
Bilek, M., Stawarczyk, K., Siembida, A., Strzemski, M., Olsze-
wski, M. and Cieślik, E. 2015b. Zawartość cukrów w sokach
drzewnych z terenu Podkarpacia. [Content of sugars in tree
saps from Podkarpacie region]. Żywność.Nauka.Technologia.
Jakość 6 (103): 53-63 (in Polish).
Briskin, D.P. 2000. Medicinal Plants and Phytomedicines. Linking
Plant Biochemistry and Physiology to Human Health. Plant
Physiology 124: 507-514.
Butkus, D. and Baltrėnaitė, E. 2007. Transport of heavy met-
als from soil to Pinus sylvestris L. and Betula pendula trees.
Ekologija 53 (1): 29–36.
Ferreira, M.L. and Domingos, M. 2012. Seasonal characterization
of antioxidant responses in plants of Ipomoea nil cv. Scarlet
O’Hara. Brazilian Journal of Biology 72: 831-837.
Harju, L. and Hylden, S.G. 1990. Birch sap as a tool for biogeo-
chemical prospecting. Journal of Geochemical Exploration 37
(3): 351-365.
Jeong, S.J., Jeong, H.S., Woo, S.H. and Shin, C.H. 2013. Con-
sequences of ultraltration and ultraviolet on the quality of
white birch (Betula platyphylla var. japonica) sap during stor-
age. Australian Journal of Crop Science 7: 1072-1077.
Jeong, S.J., Lee, CH.H., Kim, H.Y., Lee, S.H., Hwang, I.G., Shin,
C.S., Lee, J. and Jeong, H.S. 2012. Quality characteristics of
the white birch sap with varying collection periods. Journal of
the Korean Society of Food Science and Nutrition 1: 143-148.
Jiang, H., Sakamoto, Y., Tamai, Y. and Terazawa, M. 2001. Pro-
teins in The Exudation Sap from Birch Trees, Betula platy-
phylla Sukatchev var. japonica Hara and Betula verrucosa.
Her. Eurasian Journal of Forest Research 2: 59-64.
Jones, A.R.C. 2011. Sap yields, sugar content and soluble carbohy-
drates of saps and syrups of some Canadian birch and maple
species. Canadian Journal of Forest Research 17: 263-266.
Joshi, R., Adhikari, S., Patro, B.S., Chattopadhyay, S. and
Mukherjee, T. 2001. Free radical scavenging behavior of fo-
lic acid: evidence for possible antioxidant activity. Free Radi-
cal Biology and Medicine 30: 1390-1399.
Kallio, H., Ahtonen, S., Raulo, J. and Linko, R.R. 1985. Identi-
cation of the sugars and acids in birch sap. Journal of Food
Science 1: 266-269.
Kallio, H. and Ahtonen, S. 1989. Identication and seasonal varia-
tions of amino acids in birch sap used for syrup production.
Food Chemistry 33: 125–132.
Kallio, H. and Ahtonen, S. 1987. Seasonal variations of the sugars
in birch sap. Food Chemistry 25: 293-304.
Kandziora-Ciupa, M., Nadgórska-Socha, A., Ciepał, R. and
Janowicz, J. 2015. Heavy metals content and biochemical
indicators in birch leaves from polluted and clean areas. Eco-
logical Chemistry Engineering A 22 (1): 83-91.
Klinger, W., Hirschelmann, R. and Süss, J. 1989. Birch sap and
birch leaves extract: screening for antimicrobial, phagocy-
tosis-inuencing, antiphlogistic and antipyretic activity. Die
Pharmazie 44: 558-560.
Krishnaveni, M. 2013. Air pollution tolerance index and antioxi-
dant activity of Parthenium hysterophorus. Journal of Phar-
macy Research 7: 296-298.
Kūka, M., Čakste, I. and Geršebeka, E. 2013. Determination of
bioactive compounds and mineral substances in Latvian birch
and maple saps. Proceedings of the Latvian Academy of Sci-
ences. Section B. Natural, Exact, and Applied Sciences 4-5
(67): 437-441.
Lee, C.H., Cho, Y.M., Park, E.S., Shin, C.S., Lee, J.Y. and Jeong,
H.S. 2009. In vivo immune of sap of the white birch (Betula
platyphylla var. japonica). Korean Journal of Food Science
and Technology 41: 413-416.
Liaudanskas, M., Viškelis, P., Raudonis, R., Kviklys, D., Uselis,
N. and Janulis, V. 2014. Phenolic composition and antioxi-
dant activity of Malus domestica leaves. TheScienticWorld
Journal, 2014: Article ID 306217, 10 p. Available online at:
http://dx.doi.org/10.1155/2014/306217.
Lowry, O.H., Rosebrough, N.J., Farr, A.L. and Randall, R.J.
1951. Protein measurement with the Folin phenol reagent.
Journal of Biological Chemistry 193: 265-275.
Łuczaj, Ł., Bilek, M. and Stawarczyk, K. 2014. Sugar content in
the sap of birches, hornbeams and maples in south eastern Po-
land. Central European Journal of Biology 9: 410-416.
Meteoblue Weather, 2016. Archiwum pogodowe. Meteoblue AG,
Basel, Switzerland. https://www.meteoblue.com/pl/pogoda/
prognoza/archive (in Polish).
Mutlu, S., Atici, Ö. and Kaya, Y. 2009. Effect of cement dust on
diversity and antioxidant enzyme activities of plants growing
around a cement factory. Fresenius Environmental Bulletin
18: 1823-1827.
Peev, C., Dehelean, C., Mogosanu, C., Feea, S. and Corina,
T. 2010. Spring drugs of Betula pendula Roth.: biologic and
pharmacognostic evaluation. Studia Universitatis “Vasile Gol-
dis”, Seria Stiintele Vietii 20: 41-43.
Piluzza, G. and Bullitta, S. 2011. Correlations between phenolic
content and antioxidant properties in twenty-four plant species
of traditional ethnoveterinary use in the Mediterranean area.
Pharmaceutical Biology 49: 240-247.
Re, R., Pellegrini, N., Proteggente, A., Pannala, A., Yang, M. and
Rice-Evans, C. 1996. Antioxidant activity applying an im-
proved ABTS radical cation decolorization assay. Free Radi-
cal Biology and Medicine 26: 1231–1237.
Semjonovs, P., Denina, I., Fomina, A., Patetko, A., Auzina, L.,
Upite, D., Upitis, A. and Danilevics, A. 2014. Development
of birch (Betula pendula Roth.) sap based probiotic fermented
beverage. International Food Research Journal 21(5): 1763-
1767.
Shi, Q., Zhu, Z., Xu, M., Qian, Q. and Yu, J. 2006. Effect of ex-
cess manganese on the antioxidant system in Cucumis sativus
L. under two light intensities. Environmental and Experimen-
tal Botany 58: 197-205.
Singleton, V.L. and Rossi, J.A. 1965. Colorimetry of Total Phe-
nolics with Phosphomolibdic and Phosphotungstic Acid Re-
2017, Vol. 23, No. 1 (44)
BALTIC FORESTRY
239
2016, Vol. 22, No. 2 (43)ISSN 2029-9230
agents. American Journal of Enology and Viticulture 16: 144-
158.
Škrovánková, S., Mišurcová, L. and Machů, L. 2012. Antioxidant
Activity and Protecting Health Effects of Common Medicinal
Plants. Advances in Food and Nutrition Research 67: 75-139.
Svanberg, I., Soukand, R., Łuczaj, Ł., Kalle, R., Zyryanova,
O., Denes, A., Pann, N., Nedelcheva, A., Seskauskaite, D.,
Kołodziejska-Degórska, I. and Kolosowa, W. 2012. Uses of
tree saps in northern and eastern parts of Europe. Acta Societa-
tis Botanicorum Poloniae 81: 343-357.
Vincēviča-Gaile, Z. 2014. Impact of environmental conditions on
micro- and macroelement content in selected food from Lat-
via: Summary of doctoral thesis. University of Latvia, Rīga.
33 pp.
WHO, IUCN, WWF. 1993. Guidelines on the conservation of me-
dicinal plants. Gland, Switzerland, 38 pp.
Wierzbicka M. (ed.) 2015. Ekotoksykologia, rośliny, gleby, metale.
[Ecotoxicology, plants, soil, metals]. Monograa. Wyd. Uni-
wersytetu Warszawskiego. 544 pp. (in Polish).
Yan, X., Zhang, F., Zeng, CH., Zhang, M., Devkota, L.P. and
Yao, T. 2012. Relationship between Heavy Metal Concentra-
tions in Soils and Grasses of Roadside Farmland in Nepal.
International Journal of Environmental Research and Public
Health 9: 3209-3226.
Zeneli, L., Daci-Ajvazi, M., Daci, N.M., Hoxha, D. and Shala, A.
2013. Environmental Pollution and Relationship Between To-
tal Antioxidant Capacity and Heavy Metals (Pb, Cd, Zn, Mn,
and Fe) in Solanum tuberosum L. and Allium cepa L. Human
and Ecological Risk Assessment 19: 1618–1627.
Received 19 March 2016
Accepted 30 September 2016
THE BIOACTIVE AND MINERAL COMPOUNDS IN BIRCH SAP COLLECTED /.../ D. GRABEK-LEJKO ET AL.
2017, Vol. 23, No. 1 (44)