Bioactive compounds in the peel of camu camu genotypes from Embrapa’s active germplasm bank

Abstract

Our objective in this work was to evaluate the contents of the major bioactive compounds in the peel of three genotypes of camu camu at different maturity stages. The genotypes had high concentration of ascorbic acid in the peel ranging from 13.73% to 24.02%. In the ripe maturity stage the genotypes 17 and 44 presented the highest concentration of phenolics (3,299.97 mg GAE.100 g-1) and anthocyanins (165.91 g.100 g-1). Flavonols and carotenoids showed a distinct and statistically different behavior in each genotype. Genotype 44 in the ripe stage had the highest content of carotenoids (105.88 mg.100 g-1). The high contents of vitamin C and phenolic compounds make the residue of camu camu fruit processing a rich source of antioxidants to the food and/or pharmaceutical industries.

Full text

Food Sci. Technol, C ampinas, 1
Food Science and Technology ISSN 0101-2061
OI:Dhttp://dx.doi.org/10.1590/1678-457X.33716
1 Introduction
Camu-camu (Myrciaria dubia (HBK) McVaugh), belonging
to the family Myrtaceae, is a bush native to the Amazon rainforest
with round berries averaging 2.5 cm in diameter. is fruit
has high antioxidant capacity because of its high vitamin C
(2,280 mg 100 g-1) and total phenolic (1,420 mg GAE 100 g-1)
content. e pulp of camu camu is exported mainly to Japan,
Europe, and the USA (Zanattaetal., 2005; Chirinosetal., 2010;
Yuyama, 2011).
A study carried out by Chirinoset al. (2010) found the
presence of 30 dierent phenolic compounds in the camu camu
fruit, especially avan-3-ols, ellagic acid, and its derivates,
avonols and avanones. Besides polyphenols, camu camu also has
carotenoids, mainly trans-lutein and β-carotene (Azevedo-Meleiro
& Rodriguez-Amaya, 2004; Zanatta & Mercadante, 2007).
e bioactive compounds in camu camu can vary according
to the fruit’s maturity stage, detected through the peel color,
which changes during the ripening process from green to
shades of red and purple (Zanatta & Mercadante, 2007), with
an increase in the contents of ascorbic acid and anthocyanins
(Villanueva-Tiburcioetal., 2010).
Bioactive compounds exert a powerful biologic activity
and play several roles in beneting human health. ey are, on
average, secondary metabolites related with the plant defense
system against ultraviolet radiation and aggressions from insects
and pathogens (Manachetal., 2004), and with the biosynthesis
of substances that signal pollination (Rice-Evansetal., 1996).
ese naturally occurring phytochemicals are complex mixtures
that dier among plants, plant parts, and development stages
(Wink, 2004).
e goal of this study is to quantify and correlate the main
bioactive compounds and the in vitro antioxidant capacity of
camu camu peel as a function of the maturity stage in fruits of
three dierent genotypes.
2 Materials and methods
e camu camu fruit samples were collected from dierent
mother plants from the Germoplasm Bank of Embrapa Eastern
Amazon, located in Belém, state of Pará, Brazil (1°28’ S, 48°29’ W).
e genotypes named 17, 38 and 44 were chosen by its high
productivity and plague resistance. Fruits of three genotypes
were randomly chosen at three maturity stages according to the
to the color characteristics of the peel: green (90 to 100% green),
semi-ripe (10 to 80% red), and ripe (above 80% red), according
described in Table1. e whole fruits were selected, hygienized,
and manually depulped to separate the pulp, peel, and seed.
e peel was homogenized, placed in laminated plastic vacuum
packages, and stored at freezing temperature (-20 °C) until the
analyses were performed.
2.1 Ascorbic acid
AOAC method 43.065 (Association of OfficialAnalytical
Chemists, 1984), based on the reduction of
2,6-dichlorophenolindophenol sodium (DCFI) by ascorbic
acid. e results were expressed as g 100 g-1 of peel.
Bioactive compounds in the peel of camu camu genotypes from
Embrapa’s active germplasm bank
Aline SOUZA1, aise OLIVEIRA1, Rafaella MATTIETTO2, Walnice NASCIMENTO2, Alessandra LOPES1*
a
Received 12 Jan., 2017
Accepted 06 Aug., 2017
1 Laboratory of Biotechnological Processes – LABIOTEC, Graduate Program in Food Science and Technology – PPGCTA, Universidade Federal do Pará – UFPA,
Belém, PA, Brazil
2 Laboratório de Agroindústria, Empresa Brasileira de Pesquisa Agropecuária – Embrapa Amazônia Oriental, Belém, PA, Brazil
*Corresponding author: alessalopes@ufpa.br
Abstract
Our objective in this work was to evaluate the contents of the major bioactive compounds in the peel of three genotypes
of camu camu at dierent maturity stages. e genotypes had high concentration of ascorbic acid in the peel ranging from
13.73% to 24.02%. In the ripe maturity stage the genotypes 17 and 44 presented the highest concentration of phenolics
(3,299.97 mg GAE.100 g-1) and anthocyanins (165.91 g.100 g-1). Flavonols and carotenoids showed a distinct and statistically
dierent behavior in each genotype. Genotype 44 in the ripe stage had the highest content of carotenoids (105.88 mg.100 g-1).
e high contents of vitamin C and phenolic compounds make the residue of camu camu fruit processing a rich source of
antioxidants to the food and/or pharmaceutical industries.
Keywords: antioxidants; maturity; phytochemicals; residue; vitamins.
Practical Application: Production of the antioxidant extracts for use as food ingredient and/or drugs.

Bioactive compounds in the peel of camu camu genotypes
Food Sci. Technol, Campinas, 2
2.2 Total carotenoids
e total carotenoids was carried out using the method
described by Rodriguez (2001). e assay used 5 g of sample at
each maturity stage and petroleum ether as extraction solvent,
with results expressed as a function of β-carotene, absorbance
peak at 450 nm, and absorption coecient of 2,592 A
1cm
1%
.
eresults were expressed as mg 100 g-1 of peel.
2.3 Total phenolics
e total phenolics was carried out using the Folin-Ciocalteu
method described by Singleton & Rossi (1965) and modied
by Georgéetal. (2005), in which 1 to 3 g of the sample at each
maturity stage were used. To remove interfering substances, the
raw extract (obtained from the dilution of the sample in 70%
acetone and then ltration) was washed twice in Oasis HLB
6cc cartridges (Waters) with distilled water. e polyphenol
content was calculated based on the standard curve of gallic
acid, measured through the dierence between the raw extract
(interfering substances and polyphenols) and the washed extract
(interfering substances). Absorbance was read at 760 nm and
the results were expressed as GAE (gallic acid equivalent) as
mg 100 g-1 of peel.
2.4 Total anthocyanins
Total anthocyanins were quantied according to the single
pH spectrophotometric method as described by Fuleki & Francis
(1968) and revised by Lees & Francis (1972). For the sample of
the ripe and semi-ripe stages, 2 and 3 g of sample were used,
respectively. For anthocyanin extraction, a 95% ethanol solution
was used: HCl 1.5 N (85:15, v/v). Aer the extraction step, the
reading was carried out in a UV-visible spectrophotometer
(ermo Scientic, Evolution 60) with 535 nm wavelength.
eresults were expressed as mg 100 g-1 of peel.
2.5 Flavonols
e aluminum chloride reaction method was used to quantify
the avonols and avones family, as described by Medaetal.
(2005) e results were calculated based on the calibration
curve built with quercertin and expressed as mg of quercertin
equivalent (QE) per g of peel (mg QE g-1).
2.6 Antioxidant capacity
DPPH• assay
The DPPH• assay was assessed using the method of
Brand-Williamset al. (1995). e antioxidant capacity was
expressed as the concentration of extract necessary to decrease
the initial concentration of DPPH• by 50% (EC50) under the
specied experimental condition and values expressed as gpeel
g DPPH•.
ABTS+ assay
e ABTS+ assay was carried out according to the methodology
proposed by Rufinoetal. (2010), which measures the reduction
in the concentration of the radical ABTS [2,2-azino-bis
(3-ethylbenzothiazoline)-6-sulfonic acid] captured by the
sample’s antioxidants tested and by the water-soluble equivalent
of vitamin E. e extract was prepared from 1 g of sample, using
as solvent 50% methanol, 70% acetone, and distilled water,
which was homogenized, centrifuged (11,000 rpm for 15 min)
and ltered in two steps.
e samples were analyzed in triplicate aer the 2 mM
trolox standard was prepared and read at dierent dilutions
to obtain the standard curve. e reading was performed in a
spectrophotometer at 734 nm aer 6 min of mixing the ABTS
extract with the sample extract at dierent dilutions using ethyl
alcohol as blank. e result was expressed in µM trolox g
-1
of peel.
2.7 Statistical analysis
e results were analyzed through analysis of variance
(ANOVA) and Tukey’s mean comparison test with a 95%
condence interval, using the soware Statistica version7.0
(Statsoft Inc., 2004), to compare the statistical dierences
among the maturity stages and the genotypes studied. Pearson’s
correlation coecient (R) was used to assess the intensity of
the linear association between the bioactive compounds and
antioxidant capacity of the three dierent genotypes.
3 Results and discussion
In the present study, genotypes 38 and 44 had an increase
in ascorbic acid content, comparing the green and ripe stages,
while genotype 17 had a decrease during maturation, with no
Tab le 1. Bioactive compound contents (in dry basis) in camu camu peel as a function of maturity in dierent genotypes.
Genotypes Maturity stage Ascorbic acid
(g 100 g-1)
Total phenolics
(mg GAE 100 g-1)
Total Anthocyanins
(mg 100 g-1)
Flavonols
(mg QE g-1)
Total Carotenoids
(mg 100 g-1)
17 Green 17.80 ± 0.15c1,042.63 ± 17.16dnd 343.63 ± 8.95a75.62 ± 0.42d
Semi-ripe 15.37 ± 0.06e1,213.02 ± 51.72c35.34 ± 0.01d184.27 ± 6.7e73.72 ± 0.08e
Ripe 15.52 ± 0.35e3,299.97 ± 181.55a145.32 ± 0.16c 242.02 ± 3.14b72.1 ± 0.19f
38 Green 16.09 ± 0.05e1,220.71 ± 0.31cnd 184.93 ± 3.27e92.72 ± 0.09c
Semi-ripe 13.73 ± 0.07f1,576.52 ± 241.17b21.58 ± 0.01f166.64 ± 3.30f44.35 ± 0.18h
Ripe 19.06 ± 0.42b1,692.93 ± 179.88b146.88 ± 0.16b138.21 ± 1.23h 48.8 ± 0.07g
44 Green 16.75 ± 0.63e544.83 ± 104.22fnd 216.4 ± 0.51d76.76 ± 0.24d
Semi-ripe 17.06 ± 0.09d797.6 ± 179.98e25.24 ± 0.02e228.66 ± 4.65c98.48 ± 0.23b
Ripe 24.02 ± 0.18a881.46 ± 88.68e165.91 ± 0.39a142.15 ± 7.24g105.88 ± 0.25a
Values are means of triplicate determinations (n = 3) ± standard deviation. Dierent letters in the same column are signicantly dierent (p ≤ 0.05). nd: not detected.

Souzaetal.
Food Sci. Technol, C ampinas, 3
statistical dierence between the semi-ripe and ripe stages
(Table1). Genotype 44 was the one that had the highest ascorbic
acid content at the semi-ripe and ripe stages: 17.06 g 100 g
-1
and
24.02 g 100 g
-1
, respectively. Genotype 17 had the highest ascorbic
acid content at the green stage (17.79 g 100 g
-1
) compared to the
other genotypes at the same maturity stage.
Villanueva-Tiburcioetal. (2010) observed a reduction in
ascorbic acid content during maturation in the vitamin C content
in the peel of fresh camu camu fruits from the region of Ucayali,
Peru. According Chirinosetal. (2010) the ascorbic acid content
was higher in green maturity stage (2,280 mg ascorbic acid
100 g-1 fruit), but at full maturity the value of 2,010 mg ascorbic
acid 100 g-1 fruit presented 11.8% lower than in green stage.
In contrast, Alveset al. (2002) and Yuyama (2011) have
reported increases in ascorbic acid during the maturation and
ripening of the camu-camu fruit.
According Justietal. (2000) dierences in environmental
conditions (e.g., soil and climatic variations) can also aect the
vitamin C content of camu-camu fruit and Correaetal. (2011)
related that the ascorbic acid content in camu-camu fruit decreases
with the maturity stage because of the action of enzymes such
as ascorbate oxidase, phenolase, and cytochrome oxidase.
Regardless of the maturity stage, the vitamin C content
found in camu camu peel is very high compared to other
tropical fruits (Assunção & Mercadante, 2003; Mattaetal.,
2004; Rufinoet al., 2010; Almeidaetal., 2011; Yazawaet al.,
2011), and shows the potential use of this part of the fruit for
applications in the cosmetic, pharmaceutical, and supplement
industries, among others.
Total phenolic content increased in all genotypes during
maturation, but genotype 17 had a much higher increase compared
with the others at the ripe stage (3,298.98 mg GAE 100 g-1).
Genotype 44 had the lowest total phenolic content at all maturity
stages, with no statistical dierence between the semi-ripe and
ripe stages (Table1).
In the study by Villanueva-Tiburcioetal. (2010), the highest
total phenolic content was found in semi-ripe camu camu peel
(77.0 mg GAE 100 g-1). According Chirinosetal. (2010) total
phenolic contents in edible portion (peel and esh) of camu
camu increased from the full green to green–reddish stage and
then decreased by seven percent at the red stage.
Reynertsonetal. (2008) analyzed the phenolic compounds
and antioxidant activity in 14 fruits of the Myrtaceae family and
found that Myrciaria dubia had the higher total phenolic content
(1,010 mg GAE 100 g
-1
) and avonols levels of approximately six
times higher (24 mg 100 g-1) than the other fruits investigated.
e anthocyanin content increased during ripening for
all genotypes. No results were found for the green stage due to
the low amount of anthocyanins at this stage. When semi-ripe,
genotype 17 had the highest anthocyanin content (35.34 mg 100 g
-1
)
compared with the others, while at the ripe stage genotype
44stood out (165.91 mg 100 g-1). No statistical dierence was
found between genotypes 17 and 38 at the ripe stage (Table1).
Villanueva-Tiburcioetal. (2010) found an increase in peel
anthocyanin content in fresh camu camu fruits compared with the
semi-ripe and ripe stages, with values of 3.83 and 46.43 mg 100 g
-1
,
respectively.
Zanattaetal. (2005) found total anthocyanin values
ranging from 30.3 to 54 mg 100 g-1 of fresh peel (ripe stage) in
two regions of the state of São Paulo. is shows that the peel
of camu camu fruit can be considered a potential source of
anthocyanins, especially cyanidin-3-glucoside (89%) followed
by delphinidin-3-glucoside (5%).
Genotype 17 had a reduction in avonols between the green
and semi-ripe stages and an increase in the ripe stage, genotype
38 had a reduction during maturation, while genotype 44 had no
statistically dierent variation between the green and semi-ripe
stages, but a decrease at the ripe stage (Table1). e highest
avonol content was found for genotype 17 at the green stage
(343.63 mg QE 100 g-1) and the lowest was found for genotype
38 at the ripe stage (138.21 mg QE 100 g-1).
Contents in acerola, for instance, range from 175 to 625 µg QE g-1
of edible part (dry basis) (Huber & Rodriguez-Amaya, 2008).
Rutzetal. (2012) investigated some bioactive compounds
of blackberry (Rubus spp.) at dierent maturity stages and they
found the complete loss in quercertin content during maturation.
Jaakolaetal. (2002) had also observed in bilberry fruits a
reduction in quercetin concentration during the maturation.
ese authors showed a correlation between anthocyanin
synthesis and the expression of the avonoid pathway genes of
berries. Procyanidins and quercetin were the major avonoids
in green fruits, however the concentration of these compounds
decreased signicantly during the progress of ripening.
Table1 shows the relationship between carotenoid content
and maturity, which is dierent for every genotype. Genotype
17 had a slight decrease during maturation with no statistical
dierence between the semi-ripe and ripe stages; genotype 38had
a signicant decrease in carotenoid content between the green
and semi-ripe stages and an increase in the ripe stage, while
genotype 44 had an increase throughout maturation. e highest
carotenoid content was found in genotype 44 at the ripe stage,
while the lowest was found in genotype 38 in the semi-ripe stage.
It is common to observe in plants dierences in carotenoid
accumulation between tissues and cultivars. Fuetal. (2014)
showed that the dierential expression of carotenogenic genes
was unsatisfactory to justify the large dierence in carotenoid
content between cultivars of loquat, indicating that there may
be another regulatory mechanism underlying this phenomenon.
According to Rufinoet al. (2010), camu camu pulp has
mean carotenoid contents (1.32 mg 100 g-1) lower than those
of acerola (5.19 mg 100 g-1), however, higher than jaboticaba
(Myrciariacauliora) (0.76 g 100 g
-1
) and jambolan (Syzygiumcumini)
(1.13 g 100 g-1).
Genotypes 17 (42.52, 48.28, and 38.95 g peel g
-1
DPPH) and
44 (65.07, 41.03, and 53.78 g peel g-1 DPPH) had the highest
antioxidant capacity through the DPPH method in comparison

Bioactive compounds in the peel of camu camu genotypes
Food Sci. Technol, Campinas, 4
with genotype 38 (91.75, 53.35, and 54.15 g peel g-1 DPPH) at
all maturity stages (Figure1).
e highest antioxidant activity through the ABTS+ method
was found in genotype 44 at the ripe stage (1,701.63 M trolox
g-1) and the lowest was found in genotype 38 at the green stage
(911.44 M trolox g-1) (Figure2).
Rufinoetal. (2010) showed that camu camu had the highest
antioxidant activity compared with the other fruits analyzed,
with 1,237.00 M trolox g-1 (wet basis) of antioxidant activity
for its pulp and peel.
Pearson’s correlation coecient (R) was used to determine
the intensity of the linear association between the bioactive
compounds and antioxidant capacity during maturation and
in the three dierent genotypes. In genotype 17, a positive
correlation (p≤0.05) was observed between ascorbic acid and
avonols content and ABTS+ at 0.95 and 0.99, respectively.
ere was no linear correlation (p>0.05) between phenolics and
ABTS+ (-0.08) and DPPH (-0.30), because of the high content
of ascorbic acid that is sixteen times higher than phenolics
content. e results of ABTS+ and DPPH practically show only
the ascorbic acid variation.
ere is a non-linear relationship between the antioxidant
concentration and the DPPH radical scavenging activity because
of the dierent antioxidant mechanisms contribution in DPPH
radical scavenging (Chenetal., 2013).
Delva & Goodrich-Schneider (2013) found a high correlation
between DPPH and ascorbic acid in acerola juices however this
behavior was not found between DPPH and total phenolics.
For genotype 38, a negative linear correlation (p ≤ 0.05)
was found between total phenolic content and DPPH (-0.97).
enegative association in this case represents a directly
proportional relation between the presence of these bioactive
compounds and antioxidant activity since the result of the
methodology through DPPH is expressed as IC50, i.e., the higher
the antioxidant activity, the lowest its value in IC50.
Genotype 44 had a positive correlation between ascorbic acid
and ABTS+ antioxidant activity with a value of 0.88 (p ≤ 0.05).
e interaction between the bioactive compounds and
antioxidant activity in vitro is complex since it comprises several
factors and substances present in the fruit, their inter-relations,
and the dierent methodology employed in the analysis.
4 Conclusion
e high levels of ascorbic acid, phenolic compounds, and
carotenoids found in camu camu peel combined with antioxidant
capacity shows that this residue may represent a new source of
functional compounds for the improvement of human nutrition.
Clarifying the formation of bioactive compounds at dierent
maturity stages and in dierent genotypes is important since
it may provide information required for the pharmaceutical
and/or functional food industries to optimize the extraction
of these compounds, as well as help camu camu producers
choose a given variety and maturity stage according to their
commercial interests.
Acknowledgements
We are grateful to the Coordenação de Aperfeiçoamento de
Pessoal de Nível Superior (CAPES) for the scholarship. e authors
thank all who contributed directly or indirectly to this study.
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