Chemical Composition of Selected Beetroot Juices in Relation to Beetroot Production System and Processing Technology

Abstract

Market offer of vegetable juices in Europe is growing, and the vegetable species and processing technologies used become more diversified resulting in a large range of juice types. At the same time consumers look for natural and safe products with pro-health properties. The aim of this study was to evaluate the nutritional composition of selected juices based on beetroots coming from different agricultural systems and processed according to different technologies. Research material consisted of conventional and organic juices marketed in Poland, in that pure pressed juices, fermented juice and juices from concentrate, pure and combined with apple or lemon juice. The concentration of vitamin C, organic acids, total and reducing sugars, phenolic acids, flavonoids and betalains has been determined in the juices. All beetroot juices were abundant in betalains, with higher concentrations of these compounds found in pure beetroot juices when compared to juices combined with apple or lemon. Highest concentration of betanin-3-O-glucoside was found in pure conventional juice from concentrate, while highest betanidin content was found in pure organic fermented juice. Highest vitamin C contents were found in pressed organic juices combined with apple and lemon. All juices were abundant in polyphenols, mainly phenolic acids, with highest concentrations of these antioxidants found in conventional pure pressed juice. The study shows that beetroot juices, independently on the beetroot processing technology and agricultural production system, are very valuable products due to the presence of numerous bioactive compounds, especially betalains, in their composition. Therefore beetroot juice consumption should be promoted among consumers.

Full text

Original Article
Chemical Composition of Selected Beetroot Juices in Relation to Beetroot
Production System and Processing Technology
Renata KAZIMIERCZAK*, Agata SIŁAKIEWICZ, Ewelina HALLMANN,
Dominika ŚREDNICKA-TOBER, Ewa REMBIAŁKOWSKA
Warsaw University of Life Sciences WULS - SGGW, Faculty of Human Nutrition and Consumer Sciences, Department of Functional Food,
Ecological Food and Commodities, 159c Nowoursynowska Street, 02-776 Warsaw, Poland; renata_kazimierczak@sggw.pl (*corresponding
author); agatka0411@wp.pl; ewelina_hallmann@sggw.pl; dominika_srednicka_tober@sggw.pl; ewa_rembialkowska@sggw.pl
Abstract
Market offer of vegetable juices in Europe is growing, a
nd the vegetable species and processing technologies used become
more diversified resulting in a large range of juice types. At the same time consumers look for natural and safe products with
pro-health properties. The aim of this study was to evaluate the nutritional composition of selected juices based on beetroots
coming from different agricultural systems and processed according to different technologies. Research material consisted of
conventional and organic juices marketed in Poland, in that pure pressed juices, fermented juice and juices from concentrate,
pure and combined with apple or lemon juice. The concentration of vitamin C, organic acids, total and reducing sugars,
phenolic acids, flavonoids and betalains has been determined in the juices. All beetroot juices were abundant in betalains, with
higher concentrations of these compounds found in pure beetroot juices when compared to juices combined with apple or
lemon. Highest concentration of betanin-3-O-glucoside was found in pure conventional juice from concentrate, while highest
betanidin content was found in pure organic fermented juice. Highest vitamin C contents were found in pressed organic juices
combined with apple and lemon. All juices were abundant in polyphenols, mainly phenolic acids, with highest concentrations
of these antioxidants found in conventional pure pressed juice. The study shows that beetroot juices, independently on the
beetroot processing technology and agricultural production system, are very valuable products due to the presence of numerous
bioactive compounds, especially betalains, in their composition. Therefore beetroot juice consumption should be promoted
among consumers.
Keywords: beetroot juice, betalains, betanidin, betanin, organic production, phenolic compounds
Available online:
www.notulaebotanicae.ro
Print ISSN 0255
-
965X; Electronic 1842
-
4309
Not
Bot Horti Agrobo, 2016, 44(2):491
-
498
. DOI:10.15835/nbha442
10372
Introduction
Vegetables and fruit have an important role in t
he human
diet, and increasing of their consumption is recommended by
WHO/FAO and by nutritional experts around the world
(WHO, 2003). Sufficient daily consumption of these
products could help prevent major diseases, such as
cardiovascular diseases and cert
ain cancers (Key, 2011; Wang
et al
., 2014). A very important group of products in this
context are the processed fruit and vegetables, and vegetable
juices among them. The market offer and the availability of
these products are getting wider (AIJN Liquid F
ruit Market
Report, 2015). These allow both to expand the consumption
of vegetables, and at the same time to enlarge the intake of
their bioactive components during the year. Therefore,
nutritionists recommend
increasing consumption of
vegetable juices ins
tead of replacing natural products with
synthetic vitamin-
mineral supplements (Liu, 2013). Drinking
vegetable juice is one of the ways to increase a dose of essential
microelements, vitamins and other antioxidants as well as
fiber delivered to the organism
(Groele, 2010). Vegetable
juices are more easily assimilated in an organism than fresh
vegetables, as the squeezing process destroys the fiber
structure and releases bound phytonutrients (Rakin et al
.,
2004). Market offer of vegetable juices in Poland is
growing,
and the vegetable species, as well as the processing
technologies used, become more diversified, resulting in a
large range of juice types (Wołosiak and Miłosz, 2012).
Beetroot is one of the valuable vegetables in terms of
nutritional value and i
s increasingly used for juice production.
Poland is the largest EU producer of beetroots, with the share
of beetroots in the general vegetable harvests reaching nearly
67% (Eurostat, 2016). In recent years, with
the increase in
R
eceived: 15 Apr 2016. Received in revised form: 09 Nov 2016. Accepted: 11 Nov 2016. Published online: 14 Dec 2016.

Kazimierczak R et al / Not Bot Horti Agrobo, 2016, 44(2):491-498
compared to t
heir conventional counterparts. The differences
concern mainly higher sensory quality of organic fruits and
vegetables, as well as the higher content of polyphenolic
compounds and vitamins in organic agricultural crops
compared to conventional ones (Asami et al., 2003; Bavec
et
al
., 2010; Hallmann and Rembiałkowska, 2012; Średnicka
-
Tober et al., 2013; Kazimierczak et al
., 2014). This is mainly
due to different fertilization and crop protection regimes used
in organic and conventional production systems. The use of
mineral fertilizers, espe
cially nitrogen, in conventional
farming stimulates high biomass production by plants. This
can lead to disruption of other processes in plants, resulting in
poorer chemical composition of the plant materials (Heeb
et
al
., 2006; Bloksma et al., 2007). The
organic production
system, based on organic fertilization, generally favours the
synthesis of higher amounts of antioxidant substances in
plants. Therefore it can be assumed that the preserves and
juices obtained from organic vegetables are richer in these
pro-health components.
The aim of this study was to evaluate the nutritional
composition (i.e.
concentration of nutrients and bioactive
substances, especially betalains) of selected beetroot juices
available in the retail sales in Poland. The tested sampl
es
included conventional and certified organic products, in that
pure pressed juices, fermented juice and juices from
concentrate, pure and combined with apple or lemon juice.
Materials and Methods
Research material
The research was carried out in 2015 in the
Warsaw
University of Life Sciences (Poland). Research material
consisted of six commercial beetroot juices available on the
Polish market. Three of them were produced from organic
certified beetroots or beetroots combined with apple and
lemon, accordi
ng to organic farming and processing standards
(ORG-L – pressed combined with lemon, ORG-A –
pressed
combined with apple, ORG-B –
pressed fermented pure
beetroot juice) and three from conventional raw materials
(CONV-B – pressed pure beetroot juice, CONV-A –
pressed
combined with apple and CONV-CB –
pure beetroot juice
from concentrate). Organic juices were purchased in
specialized organic shop, while conventional ones –
in the
conventional supermarket. All information about the
production system, compositi
on and processing of the juices
provided by the juice producers are presented in Table 1.
Chemical analyses
Beetroot juice samples were analysed for dry matter
content, vitamin C, organic acids, total and reducing sugars,
polyphenols (flavonoids and pheno
lic acids) and betalains. All
the analyses were carried out in the analytical laboratory of the
Faculty of Human Nutrition and Consumer Science, Warsaw
University of Life Sciences, using validated protocols and
methods.
Dry matter content was determined us
ing gravimetric
method according to the Polish standard (PN-
EN
12145:2001).
Vitamin C (L-
ascorbic acid) content was determined using
a spectrophotometric method according to the relevant Polish
standard (PN–A-04019:1998).
The method involves the
oxidation of L-
ascorbic acid to dehydroascorbic acid in the
consumer income, the average
yearly consumption of fresh
beetroots in Poland decreased from 4.5 kg to 2.5 kg per capita,
partly in favour of more expensive, imported fruit and
vegetables, but also in favour of processed and semi
-
processed
vegetable products. This is most evident in b
ig cities where
processed and semi-
processed foods, allowing for quick and
easy preparation of meals, gain in popularity and where their
assortment is constantly growing (Strojewska, 2015).
Owning to high concentrations of minerals, vitamins,
flavonoids,
phenolic acids, organic acids, sugars, essential oils
and dietary fiber, but especially betalains, beetroot has an
important role in the human diet (Bogacz, 2010; Petek et al
.,
2012). From a chemical point of view, betalains are
ammonium conjugates of betalamic acid with cyclo-
DOPA
(betacyanins) and aminoacids or amines (betaxanthins). They
can be found in seeds and flowers of plants of most families of
the Caryophyllales as well as in fruit of Opuntia ficus-
indica
and Hylocereus polyrhizus (Strack et al., 2003; Moreno et al
.,
2008). However, in Europe, the main natural
source of
betalains (particularly betacyanins) in the human diet is
beetroots (Moreno et al., 2008).
Betacyanins rank among water-
soluble pigments. Their
stability is low, particularly during
heating and storage.
Therefore, next to the usually used thermal preservation
methods, lactic acid fermentation, both spontaneous and
with the use of starter bacteria
cultures
can be an alternative
method of preservation of the beetroot juices squished un
der
high pressure. During lactic acid fermentation of beetroot red
pigments are partially recovered, due to the decrease in pH to
approximately 4.0. The beetroot juice pigments are optimally
stable in an acidic environment (Klewicka et al
., 2009). Lactic
a
cid fermentation of vegetables is a common practice to
improve shelf life of foods, but also to maintain and improve
their nutritional and sensory features (Di Cagno et al
., 2013).
A great number of lactic acid bacteria were isolated from a
variety of trad
itional naturally fermented foods (Anandharaj
and Sivasankari, 2013). Availability of certain nutrients such
as minerals, vitamins, as well as acidic nature of vegetables,
provides
a good medium for lactic acid bacteria. With the
success and popularity of
sauerkraut, fermentation of many
other vegetables, such as e.g. cucumbers, cauliflower, turnips,
radishes, celery, carrots and beetroots is gaining in popularity
in many countries (Swain et al., 2014).
Vegetable as well as fruit juices are commonly clarifi
ed
during processing in order to avoid undesirable turbidity,
haze, and sediments in the final products. However nowadays
there is a rising demand for fruit and vegetable juices with the
original characteristics of the fresh products (Hongvaleerata
et al.,
2008). Therefore such a demand leads to a search for
new technologies that are able to improve the quality of the
juices. At the same time consumers more often search for
freshly pressed juices, which are richer in pectin and bioactive
substances coming f
rom raw vegetables, than for clarified
products. The turbidity of pressed juices is the result of
suspended pectin particles stemming from the plant cell walls,
and other disrupted cell materials (Pinelo et al., 2010).
In recent years, the quality of food
from organic and
conventional farming is a frequent subject of researc
h
(Rembiałkowska, 2007; Brandt et al., 2011; Hunter et al
.,
2011; Barański et al
., 2014). Most of the studies indicate
higher quality of raw materials from organic farming
492

Kazimierczak R et al / Not Bot Horti Agrobo, 2016, 44(2):491-498
493
acidic environment using 2,6
-
Dichlorofenoloindofenol. This
dye is reduced to the colourless form and at pH 4.2 is pink; the
reaction proceeds quantitatively. The weighted fresh beetroot
juice samples were
extracted in 2% oxalic acid. The solution
was filtered. The filtrate was collected and then the acetate
buffer (pH 4.0) and xylene were added to the sample. Organic
layers were separated and upper layer was transferred to
spectrometric cuvette. The light a
bsorbance was measured with
wavelength of 500 nm. The result was read from the standard
curve.
Total acidity was determined according to the relevant
Polish standard (PN-
EN 12147:2000) based on the
neutralization of the total content of acids present in t
he
solution. Water solution of fresh juice sample was titrated with
sodium hydroxide until the pH reached 8.0.
Total acidity is
converted into a corresponding acid, in this case lactic acid. The
result was calculated using a formula described in the standa
rd
(PN-EN 12147:2000).
Total sugars and reducing sugars content was determined
according to the Luff-Schoorl method (Fortuna et al
., 2003). A
fresh beetroot juice sample (2 ml) was placed in a beaker, next
mixed with 100 ml of distilled water. The beaker’s
content was
transferred to a measuring flask. 5 ml of Carrez I and Carrez II
liquids were added, mixed and filled with distilled water. The
content of the flask was filtered into a conical flask. The filtrate
was taken and then 5 ml of concentrated HCl wa
s added. Next
step was the acid hydrolysis in a hot (68
o
C) water bath. 15 ml
of NaOH was added to neutralize the sample. The content of
the flask was transferred to a measuring flask and filled with
distilled water. The extract was collected from the flas
k and 25
ml of Luff liquid was added. The sample was heated (in a flask
with reflux condenser) until it came to the boil. Then 10 ml of
30% KI, 25 ml of 25% H
2
SO
4
, and a few drops of starch were
added to the sample. Na
2
S
2
O
3
was titrated until having
obtain
ed the white colour of the solution. At the same time, a
blank test was performed without the addition of the filtrate.
The amount of the sodium thiosulfate used was subtracted
from the value of the blank test and the sugar content from the
sugar table enclosed to the methodology was read out.
The content of polyphenols (flavonoids and phenolic
acids) in beetroot juices was determined by HPLC method,
with identification of individual phenolic compounds
according to the Fluca and Sigma Aldrich standards with
a
purity of 99.5% (Shimazu equipment, USA Manufacturing
Inc, USA: two pump LC-20AD, controller CBM-
20A,
column oven SIL-20AC, spectrometer UV/Vis SPD-
20 AV)
(Hallmann, 2012).
Weighted amounts of beetroot juice
samples were put into the plastic test tubes,
then 1 ml of
methanol with 1% ascorbic acid were added, mixed thoroughly
by vortex and incubated in an ultrasonic bath (20 min at
20 °C). Then the samples were centrifuged at the speed of
3,920 × g. From the test tube 1 ml of extract was collecte
d and
re
-
centrifuged at the speed of 22,579
×
g. The amount of 500
µl of extract was taken into HPLC vials and analysed. To
analyse the phenolic compounds Synergi Fusion-
RP 80i
column (250 ×
4.60 mm) was used. The gradient flow was
applied along with two mobile phases –
acetonitrile/deionized
water (55% and 10%), pH 3.00. Time of the analysis: 36 min,
flow: 1 ml min
-1
, wavelength: 280-
370 nm. HPLC
chromatogram showing a profile of polyphenols in the tested
beetroot juice is presented on Fig. 1.
The concentr
ation of betalains in the samples was
determined by HPLC method (Slatnar et al
., 2015) (Shimazu
equipment described above). Betacyanins (betanin-5-O
-
glucoside and betanidin) were identified based on Fluka
standards with a purity of 85%. Samples of beetroot
juice were
poured into plastic tubes with 80% ethanol, next mixed
thoroughly by vortex and incubated in an ultrasonic bath (at
30 °C, in darkness). Then the samples were centrifuged at the
speed of 3,920 x g. 2.5 ml of supernatant were taken from every
p
lastic tube, next 10n HCl was added and topped up to 10 ml
with ethanol. The samples were kept in the fridge for 10 min,
next 1 ml of extract was taken up to HPLC vial and analysed.
Betacyanins (betanin-5-O-
glucoside and betanidin) have been
identified on
the basis of standards of Fluca with a purity of
85%. The column Synergi Fusion-
RP 80i (250 x 4.60 mm)
(Shimazu) has been used. The isocratic flow was applied along
with one phase: 5% acetic acid, methanol and acetonitrile (70 :
10 : 20 v/v). Time of the analysis: 12 min, flow: 1 ml min
-1
,
wavelength: 530
-
540 nm. HPLC chromatogram showing a
profile of betalains in the tested beetroot juice is presented on
Fig. 2.
Statistical procedures
Three independent replicates of each beetroot juice were
analyzed. The
results are presented as mean ± standard
deviation (SD). Using a Statgraphics 5.1. software (StatPoint
Technologies, Inc, Warrenton, Virginia, USA), the data were
subjected to a one-
way analysis of variance ANOVA, followed
by a parametric post-hoc Tukey’s test (α = 0.05). The p-
values
are given in the tables; if the result of the analysis was not
statistically significant it was designated as ‘ns’.
Results and Discussion
The results on concentration of the analysed compounds in
the beetroot juice samples are presented in Tables 2-
4 and on
Figure 3.
Betalains
All beetroot juices were abundant in betalains, however,
individual products differed significantly with regard to the
concentrations of these chemical compounds. Betanin-3-O
-
glucoside concentrations ra
nged between 156.45 and 532.42
Table 1. Production system, composition and processing technology of beetroot juices selected for the study
Symbol Production system Beetroots (%) Fruit (%) Processing
ORG-L Organic 98 2% lemon juice Pressed, pasteurized
ORG-A Organic 70 30% apple juice Pressed, pasteurized
ORG-B Organic 100 - Pressed, lacto-fermented*, pasteurized
CONV-B Conventional 100 - Pressed, pasteurized
CONV-A Conventional 50 50% apple juice Pressed, pasteurized
CONV-CB Conventional 100 - From concentrate, pasteurized
Note: *Natural, spontaneous lactic acid fermentation

Kazimierczak R et al / Not Bot Horti Agrobo, 2016, 44(2):491-498
mg 100 g
-
1
, while betanidin concentrations between 16.75 and
89.72 mg 100 g
-1
. The identified concentrations were in a range
reported in previously published studies (Cz
yżowska et al.,
2006; Szopińska and Gawęda, 2013; Kazimierczak et al
.,
2014). Higher concentrations of betalains were found in pure
beetroot juices when compared to juices combined with other
components (apple, lemon). The highest concentration of
betanin-3-O-glucoside was found in CONV-CB
–
conventional pure juice from concentrate (higher compared to
both pure pressed conventional and the organic juice).
Different trend was observed for betanidin. ORG-
B and
CONV-CB juices were richest in this bioactive com
pound
(Fig. 3). On average, conventionally produced juices contained
significantly more betanin-3-O-
glucoside than organic ones. In
contrast, organic juices, on average, were richer in betanidin.
However, it should be pointed that the differences in
formul
ations and processing methods of tested individual
organic and conventional juice samples cause that the
observations with regard to production system effects should
be interpreted cautiously. Kazimierczak et al
. (2014) found a
higher content of betanin-3-O-
glucoside in organic versus
conventional beetroots. However, this was true only for fresh,
raw produce, while fermented beetroot juices contained similar
levels of betanin-3-O-
glucoside, independently on the beetroot
cultivation system (organic or conven
tional). As shown by
Sakuta et al
. (1987), increasing soil nitrogen concentration
resulted in higher betacyanin accumulation in the American
plant Phytolacca americana
L. It is so because betalains
(including betacyanins) belong to nitrogen-
containing
colorants (Moreno et al., 2008; Petek et al
., 2012). Brandt and
Mølgaard (2001) explained that in growing environments rich
in readily assimilable nitrogen, i.e.
conventional systems,
metabolism of plants changes in the direction of intensive
production of nitrogen-
containing compounds such as
proteins and others.
Vitamin C and organic acids
Vitamin C and organic acids contents (Table 2) were
found to significantly differ between the tested juice variants.
Vitamin C concentrations ranged between 4.43 and 20.3
6 mg
100 g
-1
, while organic acids between 0.34 and 0.81 mg 100 g
-1
.
494
ORG
-
B
–
fermented pure beetroot juice was the most
abundant in organic acids. At the same time ORG-L –
pressed
juice combined with lemon and ORG
-A –
pressed juice
combined with apple conta
ined the highest levels of vitamin C,
as lemon and apple fruit are richer vitamin C sources compared
Fig. 1. Chromatographic profile of polyphenols in beetroot
juice: (1) gallic acid
; (2) chlorogenic acid; (3) caffeic acid;
(4)
ferulic acid; (5) rutinoside-3-O-quercetin; (6) glucoside-3-O
-
quercetin; (7) myricetin; (8) luteolin; (9) quercetin;
(10)
kaempferol
Fig. 2. Chromatographic profile of betalains in beetroot juice:
(a) glucoside-5-O-betanine; (b) betanidine
Fig. 3. Betanin-3-O-
glucoside (Panel A) and betanidin (Panel B)
concentration in selected commercially available organic (ORG) and
conventional (CONV) beetroot juices (mean ± SD). ORG-L
–
organic pressed beetroot juice combined with lemon, ORG-A
–
organic pressed beetroot juice combined with apple, ORG-B
–
organic pressed fermented pure beetroot juice, CONV-B
–
conventional pressed pure beetroot juice, CONV-A –
conventional
pressed beetroot juice combined with apple, CONV-CB
–
conventional pure beetroot juice from concentrate;
means with the
same letter are not significantly different at the 5% level of probability
(Tukey‘s test, p < 0.05)
(7)
(1)
(8)
(6)
(5)
(4)
(2) (3)
(10)
(9)
0,0
2,5
5,0
7,5
10,0
12,5
15,0
17,5
20,0
22,5
25,0
27,5
30,0
32,5
35,0
min
0
100
200
300
400
500
600
700
800
mV
Detector A Ch2 370nm
Detector A Ch1 250nm
0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0 11,0 min
0
25
50
75
100
125
150
175
mV
Detector A Ch2 540nm
Detector A Ch1 530nm
(a)
(b)

Kazimierczak R et al / Not Bot Horti Agrobo, 2016, 44(2):491-498
495
to beetroots and significantly enriched the juices in this
particular compound. However, surprisingly, CONV-A
–
conventional pressed beetroot juice combine
d with apple
contained the lowest vitamin C level within all tested juices,
despite being mixed with an apple juice.
On average, organic juices contained more vitamin C and
organic acids compared to the conventional ones. This
supports many authors finding
s showing higher contents of
vitamin C in organically compared to the conventionally
cultivated fruit and vegetables (Brandt et al., 2011) and can be
explained by the nitrogen fertilization strategy used in
conventional agriculture – increased fertilizatio
n tends to
reduce the contents of ascorbic acid and other carbon
-
containing chemical compounds in plants (Stefanelli et al
.,
2010). The same tendency in terms of vitamin C content was
described by Kazimierczak et al. (2014) –
fermented beetroot
juices from
organic production were found to contain
significantly more vitamin C than the conventional ones.
However, in the cited study no effect of the production system
(organic/conventional) on the content of organic acids in pure
fermented beetroot juices has been identified.
Sugars and phenolic compounds
All the tested beetroot juice samples were a rich source of
both total and reducing sugars, but also phenolic compounds.
However, individual products differed significantly with regard
to the concentrations of
these chemicals. Total sugars ranged
between 1.73 and 7.85 g 100 g
-1
, reducing sugars between 1.21
and 7.31 g 100 g
-1
, total polyphenols between 22.78 and 129.31
mg 100 g
-1
and phenolic acids between 20.43 and 127.30 mg
100 g
-1
. One of the parameters with
relatively low variation
between the analysed samples were flavonoids, with
concentrations ranging from 2.02 to 2.36 mg 100 g
-1
.
Considering the individual products, the highest
concentrations of total sugars, reducing sugars, quercetin-3-O
-
glucoside and quercetin-3-O-rutinoside were found in CONV
-
A –
conventional beetroot juice combined with apple. The
highest contents of total polyphenols, phenolic acids, including
gallic acid, were found in CONV-B –
pure pressed beetroot
juice from conventional productio
n. ORG-L –
organic
beetroot juice combined with lemon was the most abundant in
chlorogenic acid and total flavonoids, including most of the
identified individual compounds from this group. The highest
level of total flavonoids, including myricetin as well
as caffeic
Table 2. Dry matter, vitamin C, sugars and organic acids content (per 100 g of fresh matter) in selected commercially available organic (ORG) and
conventional (CONV) beetroot juices (mean ± SD)
Beetroot juice
variants
Dry
matter
(in g)
Vitamin
C
(in mg)
Total
sugars
(in g)
Reducing
sugars
(in g)
Organic
acids
(in g)
ORG
-
L
9.60 ± 0.33 b
18.33 ± 1.18 a
5.39 ±
0.10 c
1.96 ± 0.26 d
0.70 ± 0.04 b
ORG
-
A
10.40 ± 0.44 a
20.36 ± 2.07 a
6.53 ± 0.88 b
5.41 ± 0.65 b
0.72 ± 0.04 b
ORG
-
B
5.92 ± 0.29 d
13.02 ± 1.18 b
1.73 ± 0.17 e
1.21 ± 0.25 d
0.81 ± 0.02 a
CONV
-
B
7.63 ± 0.10 c
10.75 ± 0.68 c
3.33 ± 0.34 d
3.12
± 0.30 c
0.34 ± 0.01 e
CONV
-
A
9.42 ± 0.11 b
4.43 ± 0.39 d
7.85 ± 0.46 a
7.31 ± 0.71 a
0.48 ± 0.03 d
CONV
-
CB
10.21 ± 0.12 a
15.30 ± 2.45 b
4.05 ± 0.67 d
1.21 ± 0.16 d
0.60 ± 0.02 c
Average
ORG
8.64 ± 2.03
17.24 ±3.49 A
4.55 ± 2.16
2.86 ± 1.92
0.75 ± 0.06 A
CONV
9.08 ± 1.11
10.16 ± 4.79 B
5.08 ± 2.10
3.88 ± 2.65
0.47 ± 0.11 B
p-value
P
roduction system
ns
0.0031
ns
ns
< 0.0001
V
ariant of product
< 0.0001
< 0.0001
< 0.0001
< 0.0001
< 0.0001
Note: ORG-L – organic pressed beetroot juice combined with lemon, ORG-A – organic pressed beetroot juice combined with apple, ORG-B – organic pre ssed
fermented pure beetroot juice, CONV-B – conventional p ressed pure beetroot juice, CONV-A – conventional pressed beetroot juice combined with apple, CONV-
CB – conventional pure beetroot juice from concentrate; means in a column followed by the same letter are not significantly different at the 5% level of probability
(Tukey‘s test, p < 0.05); ns, not statistically significant
Table 3. Flavonoids content (mg 100 g-1 of fresh matter) in selected commercially available organic (ORG) and conventional (CONV) beetroot
juices (mean ± SD)
Beetroot juice
variants Total flavonoids Quercetin-3-O-
rutinoside
Quercetin-3-O-
glucoside Myricetin Luteolin Quercetin Kaempferol
ORG
-
L
2.35 ± 0.02 a
0.25 ± 0.004 a
0.24 ± 0.013 a
0.22 ± 0.007 d
0.15 ± 0.001 a
0.14 ± 0.002 a
1.35 ± 0.002 a
ORG
-
A
2.13 ± 0.02 c
0.19 ± 0.003 c
0.17 ± 0.07 b
0.20 ± 0.010 d
0.14 ± 0.003 b
0.12 ± 0.006 ab
1.31 ± 0.002 b
ORG
-
B
2.24 ± 0.03 b
0.16 ± 0.003 d
0.10 ± 0.005 c
0.39 ± 0.014 b
0.14 ± 0.002 bc
0.14 ± 0.025 a
1.30 ± 0.003 b
CONV
-
B
2.02 ± 0.01 d
0.12 ± 0.001 e
0.10 ± 0.006 c
0.27 ± 0.010 c
0.13 ± 0.001 cd
0.10 ± 0.002 c
1.29 ± 0.001 c
CONV
-
A
2.22 ± 0.03 b
0.24 ± 0.014 a
0.25 ± 0.011 a
0.19 ± 0.003 d
0.13 ± 0.002 d
0.12 ± 0.005 bc
1.29 ± 0.003 c
CONV
-
CB
2.36 ± 0.03 a
0.21 ± 0.013 b
0.17 ± 0.011 b
0.44 ± 0.029 a
0.14 ± 0.001 bc
0.10 ± 0.001 c
1.31 ± 0.007 b
Average
ORG
2.24 ± 0.09
0.20 ± 0.036
0.17 ± 0.060
0.27 ± 0.091
0.14 ± 0.004
A
0.13 ± 0.017 A
1.32 ± 0.024 A
CONV
2.20±0.15
0.19±0.054
0.17±0.065
0.30±0.109
0.13±0.003B
0.10±0.009B
1.30±0.009B
p-value
P
roduction system
ns
ns
ns
ns
0.0095
0.0004
0.0135
V
ariant of product
< 0.0001
< 0.0001
< 0.0001
< 0.0001
0.0001
0.0021
<
0.0001
Note: ORG-L – organic pressed beetroot juice combined with lemon, ORG-A – organic pressed beetroot juice combined with apple, ORG-B – organic pre ssed
fermented pure beetroot juice, CONV-B – conventional p ressed pure beetroot juice, CONV-A – conventional pressed beetroot juice combined with apple, CONV-
CB – conventional pure beetroot juice from concentrate; means in a column followed by the same letter are not significantly different at the 5% level of probability
(Tukey‘s test, p < 0.05); ns, not statistically significant

Kazimierczak R et al / Not Bot Horti Agrobo, 2016, 44(2):491-498
496
and ferulic acids was found in CONV
-
CB
–
conventional pure
beetroot juice from concentrate. ORG-B –
fermented organic
beetroot juice was the richest in organic acids and quercetin.
No significant differences were observed between the tested
org
anic and conventional juices (on average) in terms of dry
matter content, total and reducing sugars (Table 2), total
polyphenols, total flavonoids and total phenolic acids contents
(Tables 3, 4). The same was true for most of the identified
individual flavonoids (quercetin-3-O-rutinoside, quercetin-3
-
O-
glucoside, myricetin) (Table 3) and most of the individual
phenolic acids (gallic, chlorogenic and caffeic acid) (Table 4).
However, as already mentioned, the differences in formulations
and processing method
s of the individual organic and
conventional juice samples tested in the study do not allow
drawing strong conclusions with regard to the organic vs.
conventional production system effects on the chemical
composition of juices. Over the last 25 years, a si
gnificant
number of research studies have compared the concentrations
of bioactive compounds (i.e.
phenolics) in plant foods coming
from organic and conventional production systems (Brandt
et
al
., 2011). Authors of the most recent and comprehensive
meta-analysis summarizing results of more than 300 peer
-
reviewed comparison studies have concluded that organic crops
are, on average, characterized by significantly higher
concentrations of antioxidants, including various groups of
phenolic compounds, lower conc
entrations of cadmium and at
least four times lower incidence of pesticide residues than their
conventional counterparts, when compared across regions and
agricultural seasons (Barański et al
., 2014). On the basis of the
above meta-analysis results one could expect health-
promoting
superiority of organic compared to the conventional foods.
Final considerations and further research
To summarize, the study shows that beetroot juices are very
valuable products due to the presence of numerous bioactive
compou
nds, especially betalains, in their composition. The
concentrations of these compounds, however, seem to be
affected by both the way of processing and the beetroot
agricultural production system, e.g. the organic juice samples
tested in the study, on avera
ge, showed significantly higher
content of vitamin C, organic acids and betanidin, but also
luteolin, quercetin and kaempferol in comparison to
conventional ones. In contrast, conventionally produced juices
had a significantly higher content of ferulic acid and betanin-3
-
O-
glucoside than their organic counterparts. It is at the same
time important to mention that the variation between
individual juice samples representing one production system
was also high, showing the importance of other factors (
i.e. jui
ce
processing and formulation) for the tested parameters of
chemical composition. Further research, including higher
number of tested organic vs. conventional samples and
accounting for other relevant factors (not only processing, but
also e.g. storage, pa
cking and transport conditions known to
affect the quality of processed foods), would be necessary to
confirm the findings and/or explain the background of the
identified differences (Lee and Kader, 2000; Bloksma et al
.,
2007).
Conclusions
Beetroot juices
are very valuable products, mainly due to
the presence of numerous bioactive compounds (i.e.
betalains,
flavonoids, phenolic acids and vitamin C) in their composition.
Comparison of products processed with the use of different
technologies and coming from different (organic
/
conventional) production systems, did not allow
making
conclusions about superiority of a particular product.
However, the obtained results clearly show that introducing
any of the beetroot juices to the consumers’ diet can have a
great impact on their intake of numerous pro-
health
compounds. The beetroot juices consumption should
therefore be promoted among consumers. Special attention
should be paid to organic certified products, which guarantee
high standards of production as well as
high nutritional and
health-oriented value.
Table 4. Polyphenols and phenolic acids content (mg 100 g-1 of fresh matter) in selected commercially available organic (ORG) and conventional
(CONV) beetroot juices (mean ± SD)
Beetroot juice
variants
Total
polyphenols
Total ph
enolic
acids
Gallic
acid
Chlorogenic
acid
Caffeic
acid
Ferulic
acid
ORG
-
L
22.78 ± 0.88
c
20.43 ± 0.90 c
9.32 ± 0.18
d
9.02 ± 1.07
a
1.08 ± 0.05 ab
1.02 ± 0.04 c
ORG
-
A
73.58 ± 3.98 b
71.45 ± 4.00 b
65.50 ± 4.40 b
4.59 ± 0.24
b
0.93 ± 0.19 b
0.42 ± 0.07
d
ORG
-
B
37.39 ± 1.01 c
35.15 ± 1.03 c
34.37 ± 1.03 c
0.39 ± 0.07
c
0.22 ± 0.01
e
0.17 ± 0.04
d
CONV-B 129.31 ± 19.26 a 127.30 ± 19.27 a 120.37 ± 19.28 a 5.11 ± 0.38 b 0.49 ± 0.07 d 1.34 ± 0.10 b
CONV
-
A
66.28 ± 10.26 b
64.06 ± 10.22 b
60.97 ± 10.30 b
1.
32 ± 0.06
c
0.68 ± 0.05
c
1.09 ± 0.09 bc
CONV
-
CB
23.09 ± 0.83 c
20.73 ± 0.84 c
16.44 ± 0.87 cd
0.45 ± 0.03
c
1.13 ± 0.03
a
2.70 ± 0.33
a
Average
ORG
44.58 ± 22.09
42.34 ± 22.18
36.40 ± 23.77
4.67 ± 3.67
0.74 ± 0.40
0.54 ± 0.37 B
CONV
72.90 ± 46.42
70.70 ± 46.56
65.93 ± 45.38
2.29 ± 2.09
0.77 ± 0.28
1.71
± 0.76 A
p-value
P
roduction
system ns ns ns ns ns 0.0009
V
ariant of
product < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001
Note: ORG-L – organic pressed beetroot juice combined with lemon, ORG-A – organic pressed beetroot juice combined with apple, ORG-B – organic pressed
fermented pure beetroot juice, CONV-B – conventional pressed pure beetroot juice, CONV-A – conventional pressed beetroot juice combined with apple,
CONV-CB – conventional pure beetroot juice from concentrate; means in a column followed by the same letter are not significantly different at the 5% level of
probability (Tukey’s test, p < 0.05); ns, not statistically significant

Kazimierczak R et al / Not Bot Horti Agrobo, 2016, 44(2):491-498
Acknowledgements
This research received no specific grant from any funding
agency in the public, commercial, or not-for-profit sectors.
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