Antioxidant activity of some fresh vegetables and fruits juices

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Abstract
This paper presents the determination of some vegetables and fruits juices antioxidant activity, using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, and correlation of the results with the C vitamin concentration in the sample. It was determined, by the iodometric method, the vitamin C concentration both in the raw materials (apple, beetroot, red cabbage, tomatoes and pink grapefruit) and in the juices obtained from this. It was observed that vitamin C concentration in the juices are higher than in the raw materials, the richest in ascorbic acid being the pink grapefruit juice (81,612 mg/100ml), followed by the beetroot juice (68.014 mg/100ml). The lowest vitamin C concentration was found in the apple juice (20,401 mg/100ml). Analysing the obtained results it was conclude that between antioxidant activity and juices vitamin C concentration exists a direct correlation..
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Journal of Agroalimentary Processes and
Technologies 2011, 17(2), 163-168
Journal of
Agroalimentary Processes and
Technologies
_________________________________________________
Corresponding author: e-mail: delia_dumbrava@yahoo.com
Antioxidant activity of some fresh vegetables and fruits juices
Delia - Gabriela Dumbravă*, Nicoleta-Gabriela Hădărugă, Camelia Moldovan,
Diana- Nicoleta Raba, Mirela -Viorica Popa, B. Rădoi
1
Banat’s University of Agricultural Sciences and Veterinary Medicine, Faculty of Food Processing Technology,
Food Quality Department, 300645-Timişoara, C. Aradului 119, Romania
Received: 04 March 2011; Accepted: 14 May 2011
______________________________________________________________________________________
Abstract
This paper presents the determination of some vegetables and fruits juices antioxidant activity, using the
free radical 2,2- diphenyl- 1-picrylhydrazyl (DPPH) method, and correlation of the results with the C
vitamin concentration in the sample. It was determined, by the iodometric method, the vitamin C
concentration both in the raw materials (apple, beetroot, red cabbage, tomatoes and pink grapefruit) and in
the juices obtained from this. It was observed that vitamin C concentration in the juices are higher than in
the raw materials, the richest in ascorbic acid being the pink grapefruit juice (81,612 mg/100ml), followed
by the beetroot juice (68.014 mg/100ml). The lowest vitamin C concentration was found in the apple juice
(20,401 mg/100ml). Analysing the obtained results it was conclude that between antioxidant activity and
juices vitamin C concentration exists a direct correlation..
Keywords: vitamin C, antioxidant activity, DPPH, beetroot, red cabbage, apple, tomatoes, pink grapefruit
______________________________________________________________________________________
1. Introduction
Now, in the new millenium, the life conditions
determine that the food biologically active
substances intake be more important than energy
intake. Many diseases specific to the current
civilisation, ever-decreasing immunity, have
determined the development of a new therapeutic
concept, consisting in food-drug use for different
diseases prevention or treatment [1-3].
Plants contain high concentrations of numerous
redox-active antioxidants, such as polyphenols,
carotenoids, tocopherols, glutathione, ascorbic acid
and enzymes with antioxidant activity, which fight
against hazardous oxidative damage of plant cell
components. In animal cells, antioxidant
production is much more limited and oxidative
damage is involved in the pathogenesis of most
chronic degenerative diseases (including cancer
and heart diseases) and aging [4-7].
Therefore, plant-sourced food antioxidants like
vitamin C, vitamin E, carotenes, phenolic acids,
phytates and phytoestrogenes have been recognized
as having the potential to reduce disease risk.
Within a juices diet, the amount of potassium
inserted is about 6 times more than that in traditional
food. Following, the vegetabe juices act favorably on
the cardiac muscle whole activity, enhances the labor
of heart and have salutary effects in the
cardiovasculare diseases. In this regard the fruit
juices act better than food without salt [8,9].
Mineral substances, especially the alkali ions, have
an alkalising effect, neutralizing the hydrochloric
acid from the stomach mucosa. This action,
complementary to the pectic substances, makes that
fruit juices to be indicate for the hyperacidity control,
in the case of digestive diseases.
Delia -Gabriela Dumbravă et. al. / Journal of Agroalimentary Processes and Technologies 2011, 17(2)
164
First, absence of fat, and the large amount of
sugars and vitmanins, on the other hand, make of
fruit and vegetable juices valuable adjuvants in
liver and gall bladder diseases treatment. Due to
the low nitrogenous substances content and of
alkalizing action, juices are indicated in acute and
chronic kidney diseases, especially in those that
begins by retaining albumine, are recommended
and for pregnant women [1,9].
Fruit and vegetable juices also prevent the
formation of kidney and gall stones, due to their
potassium salts richness. Are recommended in
acidosis, diabetes, undernutrition, gout, aging
tissues. Recent scientific studies have also claimed
that the antioxidants found in most fruits and
vegetable juices can help lower a person's risks of
developing Alzheimer's disease [10].
Vegetable juices, especially those that are low in
calories, are affective in obesity treatment, because
it attenuates hunger and allows water excess
remove, due to the potassium salts [11].
In the infants and children foods, fruit and
vegetable juices provides to the body the needs of
mineral substances and vitamins [12].
The fruit or vegetable juices with pulp are very
important, thase being richer in nutrients,
cellulose, pectic substances, than the clear juices.
In the fruit and vegetable juices are found
relatively high amounts of isothiocyanate, phenolic
antioxidants, indoles and flavones that have a
proven anti-cancer action. Epidemiological studies
has consistently linked abundant consumption of
fruits and vegetables to a reduction of the risk of
developing several cancers. The mechanisms
responsible for this chemopreventive effect still
remain largely unknown but is likely related to the
presence of phytochemicals associated with fruits
and vegetables [13].
Complex therapeutic effects of fruit and vegetables
are correlated with the presence of plant
polyphenols, particularly bioflavonoids with
different structures and complex biological
functions. Thus, of the over 500 known flavonoid
compounds, 150 have biological activity, and act
as vitamin P, with protective effect in
cardiovascular diseases, with antioxidant,
antiinflammatory and antitumor action [14].
Many analytical methods have been used for
antioxidant monitoring, for instance phenolics in fruit
have been monitored by HPLC [15,16] or
colorimetrically using the Folin Ciocalteu reagent
[17]. The total antioxidant capacity of foods and
plant extracts has been assessed by using
spectrophotometric methods with DPPH· (2,2-
diphenyl-1-picrylhydrazyl) [18-20], ABTS+· (2,2’-
azinobis(3-ethylbenzothiazo-line- 6-sulfonic acid))
[18,19] or Fe3+-TPTZ (2,4,6-tripyridyl-s-triazine)
[21].
The purpose of this paper is to analyze comparatively
several types of fruit and vegetable juices, respecting
the antioxidante activity (by the DPPH method) and
C vitamin content.
.2. Materials and methods
It was used raw materials from the domestic market.
Juices were obtained from fresh raw materials
undergo operations of scraping, squeezing and
filtering. For each samples of raw material and juice
it was determinated the vitamin C content and for
each juice sample was eavaluated the antioxidant
activity using the free radical DPPH method.
Determination of vitamin C. In order to determine the
C vitamin content, it was used the adapted iodometric
method. The method principle is color reaction
between starch and KI + I solution. Determination of
C vitamin is made with the aid of K
2
Cr
2
O
7
in the KI-
starch presence. Initially, C vitamin is oxidized and
then the following reaction takes place:
Cr
2
O
7
2-
+ 6 I
-
+ 14 H
+
= 3 I
2
+ 2 Cr
3+
+ 7 H
2
0
Thus liberated iodine stains starch blue. Was weighed
a sample on analytical balance, then was brought
quantitatively into a titration vessel, were added 10
ml of 2n hydrochloric acid, diluted to 50 ml with
distilled water, triturated, added 1 ml of 1% starch
solution (freshly prepared) and 1 ml 0.1 N potassium
iodide, after which the solution was titrated with 0.1
N potassium dichromate until persistent blue color.
Quantification of vitamin C content was done
according to the relation: 1 ml 0.1 N potassium
dichromate is equivalent to 0.008806 g vitamin [22].
All determinations were performed in triplicate,
calculating their arithmetic mean.
Antioxidant activity determination.DPPH (2,2-diphenyl-
1-pycrylhydrazyl) is one of the most stable organic
nitrogen radicals and commercially available and has
maximum UV-VIS absorbance at 517 nm, giving a
bluish color.
Delia -Gabriela Dumbravă et. al. / Journal of Agroalimentary Processes and Technologies 2011, 17(2)
165
In time of reduction process, solution fade from
purple to yellow, the DPPH free electron mating
with an antiradical antioxidant hidrogen, passing in
reduced DPPH-H:
DPPH DPPH-H
purple yellow
Unfolding reaction was
monitored
spectrophotometrically
[23].
It was determined the antioxidant activity of pink
grapefruit, apple, beetroot, red cabbage and
tomatoes natural juices (clear, without pulp).
Materials used were:
- solution 1mM DPPH (2,2-diphenyl-1-
pycrylhydrazyl free radical, MP
Biomedicals, LLC-Germany, in ethanol);
- ethanol 96% (Merck).
For each analyzed juice were taken samples which
were diluted with distilled water 1:100, because at
lower dilutions happening instantly fading
samples.
In an stoppered tube
were introduced:
0,3 ml diluted sample, 2,6 ml solvent (ethanol) and
then 0,3 ml DPPH 1mM solution, after wich this
blend was introduced in the spectrophotometer
cuvette, for compensation using ethanol or
acetone. The absorbance at 517 nm
and
its
variation over time was recorded. The records
were made with the Perkin Elmer, Lambda 25
spectrophotometer.
Based on VIS absorption spectra of the different
concentration DPPH solutions (figure 1.) was
obtained calibration curve: Absorbance (517 nm) =
f (c, mM) (figure 2.).
To quantify the antioxidant activity, slope was
calculated for solutions of DPPH and reaction rate
was determined as the ratio between DPPH
concentration derived as a function of time,
according to equation:
v = c/t
If the reaction rate is higher, the better antioxidant
capacity.
Figure 1. DPPH standard solution VIS spectra
Figure 2. DPPH calibration curve
3. Results and discussions
Vitamin C level. In the table 1. and 2. (figures 3. and
4.) are the results on vitamin C content of juices and
raw materials.
Table.1. Vitamin C content of raw materials
Abs
Linea r (Abs)
Delia -Gabriela Dumbravă et. al. / Journal of Agroalimentary Processes and Technologies 2011, 17(2)
166
Figure 3. Vitamin C content of raw materials
Between fruits and vegetables examined, the
highest vitamin C content was found in the pink
grapefruit (35,359 mg/100g), followed by the
beetroot (33,840 mg/100g) and red cabage (23,706
mg/100g), the lowest vitamin C content was in
apple (7,016 mg/100g). This results are well
corelated with the literature data [
24-26].
Table 2. Vitamin C content of juices
Sample Vitamin C (mg/100ml suc)
Apple juice 20,4
Pink grapefruit juice 81,6
Beetroot
juice
68,0
Red cabbage juice 60,4
Tomatoes juice 23,3
Figure 4.Vitamin C content in juices
There is a higher concentration of vitamin C in
juices than in raw materials, the richest in ascorbic
acid being pink grapefruit juice (81,612
mg/100ml), folowed by the beetroot juice (68.014
mg/100ml).
The lowest value of the vitamin C concentration was
obtained for apple juice (20,401 mg/100ml).
Antioxidant activity. The results concerning
antioxidant activity of the samples, expressed by the
average reaction speed of DPPH reaction, in µM/s,
are presented in the table 3 (figure 5.). Values were
calculated using calibration DPPH curve pentru
DPPH and Microsoft Excel programme, on basis of
the spectrophotometric curves recorded on for each
sample (figures 6-10).
Table 3. Average reaction speed of DPPH in the presence
of the analized sample
Figure 5. Average reaction speed of DPPH in the presence
of the analized sample
The greater reaction speed of DPPH was in the
presence of pink grapefruit juice (5,235 µM/s), that
can appreciate such as having the strongest
antioxidant activity of all samples analyzed. This is
followed, in descending order, beetroot juice (v=
5,087 µM/s), red cabbage juice (v=5,040 µM/s),
tomatoes juice (v=3,154 µM/s) and apple juice
(v=3,133 µM/s).
Correlating results concerning the antioxidant
activity with those concerning the vitamin C content,
can be seen as the antioxidant activity varies in direct
proportion to the vitamin C concentration, for all the
analysed samples.
Delia -Gabriela Dumbravă et. al. / Journal of Agroalimentary Processes and Technologies 2011, 17(2)
167
Figure 6. Time variation of the DPPH 1mM solution in
the presence of pink grapefruit juice diluted 1:100
Figure 7. Time variation of the DPPH 1mM solution in
the presence of apple juice diluted 1:100
Figure 8. Time variation of the DPPH 1mM solution in
the presence of beetroot juice diluted 1:100
Figure 9. Time variation of the DPPH 1mM solution in
the presence of red cabbage juice diluted 1:100
Figure 10. Time variation of the DPPH 1mM solution in
the presence of tomatoes juice diluted 1:100
4. Conclusions
This paper aimed to determine the comparative
antioxidant activity (using the DPPH free- radical
method) of some natural, fresh vegetable and fruit
juices (pink grapefruit, apple, beetroot, red cabbage,
tomatoes). Knowing that vitamin C is one of the most
powerful natural antioxidants we try to establish a
correlation between antioxidant activity and vitamin
C content of the analysed juices. The results of
experiments may be summarized as:
Between fruits and vegetables examined, the
highest content of vitamin C is present in
pink grapefruit, followed by the beetroot and
red cabbage and the lowest vitamin C content
is found in apple.
Vitamin C concentration is higher in the
juices than in the raw materials, the richest in
ascorbic acid being pink grapefruit juice,
followed by the beetroot juice. The lowest
concentration of vitamin C was obtained for
apple juice.
For all the analysed samples the antioxidant
activity varies in direct proportion with the
vitamin C concentration.
References
1. I. Jianu, Delia Dumbravă, Factori de protecţie
alimentari, Ed. Mirton, Timişoara, 2001
2. Costin G.M., Segal R. Alimente functionale, Ed.
Academica, Bucuresti, 1999.
3. Safta, M., Super-antioxidanţii naturali în
alimentaţie şi medicină, Editura Sudura,
Timişoara, 2002.
4. Gey K.F., Puska P., Jordan, P., Moser U.K., Total
antioxidant capacity of plant foods. Inverse
correlation between plasma vitamin E and
mortality from ischemic heart disease in cross-
cultural epidemiology, Am. J. Clin. Nutr., 1991,
53(1), 326S-334S.
Delia -Gabriela Dumbravă et. al. / Journal of Agroalimentary Processes and Technologies 2011, 17(2)
168
5. La Vecchia, C., Altieri, A., Tavani, A.,
Vegetables, fruit, antioxidants and cancer: a
review of Italian studies, Eur. J. Nutr. 2001,
40(6), 261-267, doi: 10.1007/s394-001-8354-9
6. Schaffer S., Schmidt-Schillig, S., Muller,
W.E., Eckert, G.P., Antioxidant properties of
mediterranean food plant extract geographical
differences, J. Physiol. Pharmacol., 2007,
56(Suppl.1), 115-124, PMID: 15800389
7. Pioschi A.M., Cheregi M.C., Danet A.F., Total
antioxidant capacity of some commercial fruit
juices: electrochemical and
spectrophotometrical approaches, Molecules,
2009, 14(1), 480-493, PMID:19158657
8. Alexan M., Bojor O., Fructele şi legumele -
factori de terapie naturala, Ed. Ceres,
Bucureşti, 1983.
9. Adebawo O., Salau B., Ezima E., Oyefuga O.,
Ajani E., Idowu G., Famodu A., Osilesi O.,
Fruits and vegetables moderate lipid
cardiovascular risk factor in hypertensive
patients, Lipids in Health and Disease, 2006,
5, 14, doi:10.1186/1476-511X-5-14
10. Dugan D., The Importance of Fruit and
Vegetable Juices in Nutrition,
http://www.articlesbase.com/nutrition-
articles/the-importance-of-fruit-and-vegetable-
juices-in-nutrition-21760.html
11. Anne Hart, Can vegetable juices lower your
blood pressure and help you lose weight?,
News: Health & Science, 29 oct., 2009,
http://www.groundreport.com/Health_and_Sci
ence/Can-vegetable-juices-lower-your-blood-
pressure-and/2910178
12. Winiarska-Miekzan A., Novak K.,
Determining the content of some minerals in
fruit and vegetable baby juices, J. Elementol.,
2008, 13(3), 433-442
13. Gingras D., Béliveau R., Towards a global
assessment of the anticancer properties of
fruits and vegetables: the Montreal anticancre
nutrinome project, Proc. Ist IS on Hum. Health
Effects of F&V, Ed.: Y. Desjardins, 2007, ISHS
Acta Horticulturae 744,
http://www.actahort.org/members/showpdf?bo
oknrarnr=744_15
14. Segal B., Segal R., Tehnologia produselor
alimentare de protecţiei, vol. I, II, Ed. Ceres,
Bucuresti, 1991.
15. Sakkiadi A.V., Stavrakakis M.N.,
Haroutounian S.A., Direct HPLC assay of five
biologically interesting phenolic antioxidants
in varietal greek red wines, Lebensm.-Wiss. u.-
Technol., 2001, 34(6), 410-413,
doi:10.1006/fstl.2001.0792
16. Tung Y.T., Wu J.H., Kuo Y.H., Chang S.T.
Antioxidant activities of natural phenolic
compounds from Acacia confusa bark, Bioresour.
Technol., 2007, 98(5), 1120-1123,
doi:10.1016/j.biortech.2006.04.017
17. Jayaprakasha G.K., Girennavar B., S. Patil B.S.
Radical scavenging activities of Rio Red
grapefruits and Sour orange fruit extracts in
different in vitro model systems, Bioresour.
Technol., 2008, 99(10), 4484-4494,
doi:10.1016/j.biortech.2007.07.067
18. Thaipong, K., Boonprakob, U., Crosby K.,
Zevallos-Cisneros L., Byrne D.H., Comparison of
ABTS, DPPH, FRAP, and ORAC assays for
estimating antioxidant activity from guava fruit
extracts, J. Food Compos. Anal., 2006, 19(6-7),
669-675, doi: 10.1016/j.jfca.2006.01.003
19. Rivero-Perez M.D., Muniz P., Gonzalez-Sanjose
M.L., Antioxidant profile of red wines evaluated
by total antioxidant capacity, scavenger activity,
and biomarkers of oxidative stress methodologies,
J. Agric. Food Chem., 2007, 55(14), 5476-5483,
doi: 10.1021/jf070306q
20. Molyneux P., The use of the stable free radical
diphenylpicrylhydrazyl (DPPH) for estimating
antioxidant, Songklanakarin J. Sci. Technol.
2004, 26(2), 211-219.
21. Gil M.I., Tomas-Barberan F.A., Hess-Pierce B.,
Kader A.A., Antioxidant capacities, phenolic
compounds, carotenoids, and vitamin C
compounds, carotenoids, and vitamin C and plum
cultivars from California, J. Agric. Food Chem.
2002, 50(17), 4976-4982
22. Morait Gh., „Controlul analitic al
medicamentelor”, Ed. Medicală, Bucureşti, 1977.
23. Huang D., Gu B., Prior R.L., The chemistry
behind antioxidant capacity assays, J. Agric.
Food Chem., 2005, 53(6), 1841-1856, doi:
10.1021/jf030723c
24. *** National Nutrient Database. Nutrient Data
Laboratory of the US Agricultural Research
Service. http://www.nal.usda.gov/fnic/foodcomp/
search/. Retrieved 2007-03-07.
25. *** Vitamin C Food Data Chart. Healthy Eating
Club,http://www.healthyeatingclub.com/info/boo
ks-phds/books/foodfacts/html/data/data4i.html.
Retrieved 2007-03-07
26. *** Natural food-Fruit Vitamin C Content. The
Natural Food Hub. http://www.naturalhub.com
/natural_food_guide_fruit_vitamin_c.htm.Retriev
ed 2007-03-07
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    The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple DPPH. (2,2-diphenyl-1-picrylhydrazyl)/DPPH (2,2-diphenyl-1-picrylhydrazine). Trolox was chosen as a standard antioxidant. In the case of the spectrophometric method, the absorbance decrease of the DPPH. solution was followed. For the biamperometric method, the influence of some parameters like the potential difference, DeltaE, DPPH. concentration, and Trolox concentration was investigated. The calibration graph obtained for Trolox presents linearity between 5 and 30 microM, (y=0.059 x + 0.0564, where y represents the value of current intensity, expressed as microA and x the value of Trolox concentration, expressed as muM; r(2)=0.9944). The R.S.D. value for the biamperometric method was 1.29% (n=10, c=15 microM Trolox). In the case of the spectrophotometric method, the calibration graph obtained for Trolox presents linearity between 0.01 and 0.125 mM (y= -9.5789 x+1.4533, where y represents the value of absorbance and x, the value of Trolox concentration, expressed as mM; r(2)=0.9963). The R.S.D. value for the spectrophotometric method was 2.05%. Both methods were applied to total antioxidant activity determination in real samples (natural juices and soft drinks) and the results were in good agreement.
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    Case-control studies have suggested that a diet rich in fresh fruit and vegetables protects from the risk of most common epithelial cancers, including those of the digestive tract, and also several nondigestive neoplasms; however, selections in cohort studies have been generally weaker. To review the relation between frequency of consumption of vegetables and fruit, estimated intake of selected antioxidants and the risk of cancer at different sites. Systematic overview of data, with specific focus on a network of case-control studies conducted in Italy from 1983 to 1999. The relative risks (RR) of digestive tract neoplasms were reduced in subjects reporting highest vegetable intake. A protective effect of vegetables was also observed for hormone-related neoplasms. Fruit was related to a reduced RR of cancers of the upper digestive tract, stomach and urinary tract. With reference to the role of selected antioxidants, beta-carotene, vitamins C and E showed a significant inverse relation with oral and pharyngeal, esophageal and breast cancer risk. Against colorectal cancer, the most consistent protective effects were provided by carotene, riboflavin and vitamin C, but inverse relations were observed also for calcium and vitamin D. Fruit and vegetable consumption in Mediterranean populations appears to provide protection against several types of neoplasms.
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