Chemical characterization, antioxidant properties, and volatile constituents of naranjilla (Solanum quitoense Lam.) cultivated in Costa Rica

Abstract

Naranjilla (Solanum quitoense Lam.) is a native fruit of the Andes, cultivated and consumed mainly in Ecuador, Colombia, and Central America. Because of its pleasant aroma and attractive color, it has high potential as an ingredient of products such as juices, nectars, and jams. The main characteristics of mature naranjilla fruits cultivated in Costa Rica were assessed, including sugar content, total titratable acidity, total soluble solids, oxygen radical absorbance capacity (H-ORAC), and total polyphenolic and ascorbic acid content. Carotenoid and volatile compound identification was also done. The samples showed sucrose, glucose, and fructose content of 1.6 +/- 0.3, 0.68 +/- 0.05, and 0.7 +/- 0.1 g/100 g, respectively. Total titratable acidity was 2.63 +/- 0.07 g citric acid equivalent / 100 g and total soluble solids amounted to 9.1 +/- 0.5 degrees Brix. H-ORAC value was 17 +/- 1 micromol Trolox equivalent /g, total polyphenolic content was 48 +/- 3 mg gallic acid equivalent /100 g and ascorbic acid content was 12.5 +/- 0.0 mg/100 g. Carotenoid content of the whole fruit and pulp was 33.3 +/- 0.6 and 7.2 +/- 0.3 microg/g, respectively. The predominant carotenoid among the compounds identified in the whole fruit was beta-carotene. Ten volatile compounds were identified in naranjillapulp, the predominant being methyl butanoate. The chemical composition of naranjilla cultivated in Costa Rica does not seem to differ from that previously reported in studies at different locations.

Full text

88
ARCHIVOS LATINOAMERICANOS DE NUTRICION
Organo Oficial de la Sociedad Latinoamericana de Nutrición Vol. 59 Nº 1, 2009
Chemical characterization, antioxidant properties,
and volatile constituents of naranjilla (Solanum quitoense Lam.)
cultivated in Costa Rica
Óscar Acosta, Ana M. Pérez, Fabrice Vaillant
Centro Nacional de Ciencia y Tecnología de Alimentos (CITA), Universidad de Costa Rica, San José, Costa Rica.
Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD),
Département Performances des systèmes de production et de transformation tropicaux (PERSYST), France
SUMMARY. Naranjilla (Solanum quitoense Lam.) is a native fruit
of the Andes, cultivated and consumed mainly in Ecuador, Colombia,
and Central America. Because of its pleasant aroma and attractive
color, it has high potential as an ingredient of products such as juices,
nectars, and jams. The main characteristics of mature naranjilla fruits
cultivated in Costa Rica were assessed, including sugar content, total
titratable acidity, total soluble solids, oxygen radical absorbance
capacity (H-ORAC), and total polyphenolic and ascorbic acid content.
Carotenoid and volatile compound identification was also done. The
samples showed sucrose, glucose, and fructose content of 1.6 ± 0.3,
0.68 ± 0.05, and 0.7 ± 0.1 g/100 g, respectively. Total titratable acidity
was 2.63 ± 0.07 g citric acid equivalent / 100 g and total soluble
solids amounted to 9.1 ± 0.5 ºBrix. H-ORAC value was 17 ± 1 μmol
Trolox equivalent / g, total polyphenolic content was 48 ± 3 mg
gallic acid equivalent / 100 g and ascorbic acid content was 12.5 ±
0.0 mg/100 g. Carotenoid content of the whole fruit and pulp was
33.3 ± 0.6 and 7.2 ± 0.3 μg/g, respectively. The predominant
carotenoid among the compounds identified in the whole fruit was
ß-carotene. Ten volatile compounds were identified in naranjilla pulp,
the predominant being methyl butanoate. The chemical composition
of naranjilla cultivated in Costa Rica does not seem to differ from
that previously reported in studies at different locations.
Key words: Solanum quitoense Lam., chemical composition,
antioxidants, volatile compounds.
RESUMEN. Caracterización química, propiedades antioxidantes
y constituyentes volátiles de naranjilla (Solanum quitoense Lam.)
cultivada en Costa Rica. La naranjilla (Solanum quitoense Lam.) es
una fruta nativa de los Andes, cultivada y consumida principalmente
en Ecuador, Colombia y América Central. Las principales
características de frutas de naranjilla maduras cultivadas en Costa Rica
fueron evaluadas, incluyendo contenido de azúcares, acidez titulable
total, sólidos solubles totales, capacidad de absorbancia de radicales
de oxígeno (H-ORAC) y contenido de polifenoles totales y ácido
ascórbico. La identificación de carotenoides y compuestos volátiles
fue también realizada. Las muestras presentaron contenidos de sacarosa,
glucosa y fructosa de 1.6 ± 0.3, 0.68 ± 0.05 y 0.7 ± 0.1 g/100 g,
respectivamente. La acidez titulable total fue 2.63 ± 0.07 g equivalentes
de ácido cítrico / 100 g y los sólidos solubles totales fueron 9.1 ± 0.5
ºBrix. El valor de H-ORAC fue 17 ± 1 μmol equivalentes de Trolox /
g, el contenido de polifenoles totales fue 48 ± 3 mg equivalentes de
ácido gálico / 100 g y el contenido de ácido ascórbico fue 12.5 ± 0.0
mg/100 g. El contenido de carotenoides de la fruta completa y la pulpa
fue 33.3 ± 0.6 y 7.2 ± 0.3 μg/g, respectivamente. El carotenoide
predominante en los compuestos identificados en las frutas completas
fue ß-caroteno. Diez compuestos volátiles fueron identificados en la
pulpa de naranjilla, siendo el predominante el butanoato de metilo. La
composición química de naranjilla cultivada en Costa Rica aparenta
no diferir de aquella reportada previamente en estudios realizados en
lugares diferentes.
Palabras clave: Solanum quitoense Lam., composición química,
antioxidantes, compuestos volátiles.
INTRODUCTION
Naranjilla (Solanum quitoense Lam.) is a native fruit of
the Andes, cultivated and consumed mainly in Ecuador, Co-
lombia, and Central America. The tree grows best between
1200 and 2300 m above sea level (m asl); it is neither a tropi-
cal nor a temperate plant (1). The fruit is round and its peel is
covered with brittle hairs. During ripening, naranjilla turns
from green to orange, and the fruit is climacteric, with a rela-
tively low respiration rate even during the climacteric peak
(2). Even though the fruit is sometimes consumed and pro-
cessed at earlier stages of maturity (due to the pulp’s attrac-
tive greenish color), total soluble solids increase with matu-
rity, which results in a sweeter pulp at later stages. The pH
does not vary significantly with maturation (3).
The fruit contains four compartments separated by mem-
branous partitions and filled with pulp, which has a some-
what acidic flavor and a pleasant delicate aroma. It has nu-
merous flat and hard seeds. The flavor of naranjilla has been
described as sweet, similar to a mixture of banana, pineapple,
and strawberry (4).
According to Heiser and Anderson (1), naranjilla trees

89
CHEMICAL CHARACTERIZATION, ANTIOXIDANT PROPERTIES, AND VOLATILE CONSTITUENTS
were introduced over a half century ago to Costa Rica. Current
estimates indicate about 30-50 ha cultivated with the crop. Fruits
are usually sold fresh in local markets and supermarkets and are
used to produce beverages, with the addition of water and sugar.
As for processed products, naranjilla jam may be the only cur-
rently produced in commercial quantity in Costa Rica.
Despite the fact that naranjilla pulp is mostly consumed in
Latin America, either in fresh form or as a sweetened drink,
authors agree that the fruit has high potential as an ingredient
for products such as juices, nectars, ice creams, candies, jams,
jellies, toppings, sherbets, sauces, and other cooked confec-
tions (5, 6). The pulp’s green color may be an advantage for
the food industry, but it should be protected from oxidation so
it does not turn brown that quickly.
Since ripe naranjilla fruits are highly susceptible to me-
chanical damage and fungal attack, fruits are usually harvested
green, but when they reach physical maturity. Therefore, fruits
are more easily managed and marketed for a longer time. It
should be considered that fruits harvested at later maturity
stages show better quality characteristics when ripe that those
harvested at earlier stages (3). At ambient temperature, the
shelf life of physiologically mature fruits is only 6-8 d long
after harvest (2, 5). Arango et al (2) recommended several
postharvest handling systems for naranjilla and concluded that
fruits at physiological maturity can be maintained green for
50 d when packed inside polyethylene bags with an ethylene
absorber and refrigerated at 7.5ºC. Morton (5) indicated that
fruits picked half-colored can be stored for 1 or 2 mo at 7.22-
10ºC and relative humidity of 70-80%.
As for volatile constituents of naranjilla, Brunke et al (4)
used gas chromatography / mass spectrometry analysis and
sensory evaluation with a gas chromatographic sniffing de-
tector to identify components and determine their influence
on the flavor of the fruit. It was determined that the methyl
and ethyl esters of lower carboxylic acids contributed much
to the typical naranjilla flavor, but it was not possible to find
one or more impact compounds, which made researchers sus-
pect that the yet unidentified substances that possess strong
odors play an important role in the flavor complex of the fruit.
Osorio et al (7) concluded that glycosides isolated from
Solanum quitoense leaves have a role as flavor precursors
because they produce several volatile compounds with pleas-
ant sensorial notes by the action of some enzymes present in
the fruit. These generated volatile compounds may be impor-
tant with respect not only to the fruit flavor but also to the
flavor of the processed products because they would be re-
leased during processing. In a different study, with the aid of
multilayer coil countercurrent chromatography, subsequent
acetylation, and liquid chromatographic purification of a gly-
cosidic mixture obtained from S. quitoense leaves, three C13-
norisoprenoid glucoconjugates were isolated by Osorio et al
(8) in pure form.
There is great similarity between S. quitoense L. and S.
vestissimum D. with regard to both the shape of the plant and
the aspect of the fruit. However, aromas are rather different.
Authors have extensively studied the volatile constituents of
the second fruit (9), glycosidically bound aroma compounds
from its pulp and peelings (10), change in volatile compounds
during maturation (11), and volatile constituents from its
peelings (12).
The characterization of naranjilla cultivated in Costa Rica,
in terms of chemical composition, antioxidant properties, and
volatile constituents will be critical in increasing this crop’s
value in local and regional markets, as a fresh fruit and as raw
material for processed products.
MATERIALS AND METHODS
Plant material
Fully mature naranjilla fruits were harvested from several
trees in a plantation located in Heredia, Costa Rica (Helénica
Proverde S.A.). The agroecological characteristics are as
follows: geographical position 10º 01' 59'’ N, 84º 02' 41'’ E;
soil of volcanic origin; altitude, 1360 m asl; annual average
precipitation, 2479.7 mm; annual average temperature, 18.7ºC;
and annual average relative moisture, 87%. Fruits were
manually sorted for physical and microbiological damage and
then cleaned, washed, and sanitized by immersion for 3 min
in a 150-ppm solution of sodium hypochlorite. Only ripe fruits
(75-100% orange color in peel) were analyzed.
Methods of analysis
Analyses were conducted on four separate fruit lots (ob-
tained from the same location but on different dates). Fruits
were cut in halves and pulp was extracted by using an indus-
trial finisher with a 1.5-mm sieve. After the pulp was obtained,
one part was taken for moisture, total titratable acidity, pH,
total soluble solid, and color analyses. The rest of the pulp
was immediately frozen by immersion in liquid nitrogen, and
a portion was used to determine total polyphenolic content.
The remainder was then freeze-dried and stored at -20ºC in
laminated bags until further analyses. For carotenoid and vola-
tile compound analyses, whole fruits from two of the four lots
were frozen until analyses.
Moisture, ash, protein, dietary fiber, total titratable acidity
(expressed as citric acid equivalent) and pH were determined
using standard AOAC methods (13). Fat content was deter-
mined using the Soxhlet method (ether extraction) (14).
Available carbohydrate content was determined by difference,
from moisture, ash, protein, fat, dietary fiber, and total
titratable acidity analyses. Total sugars (sucrose, glucose, and
fructose) were determined using a Shimadzu LC-6A high-
performance liquid chromatography (HPLC) system, equipped
with an Alltech Econosphere NH2 column with a mixture of

90 ACOSTA et al.
acetonitrile and bidistilled water for the mobile phase. En-
ergy content was calculated using the general factors of 4, 4,
and 9 calories per g of protein, carbohydrate, and fat, respec-
tively (15). Color was measured with a HunterLab ColorFlex
CX1192 colorimeter.
Antioxidant capacity was measured in terms of hydrophilic
oxygen radical absorbance capacity (H-ORAC), following the
method described by Ou et al (16) and adapted for manual
determination by Vaillant et al (17), expressing results as μmol
Trolox equivalent / g. Total polyphenolic compounds were
determined by using a modified Folin-Ciocalteu assay
described by Georgé et al (18) with gallic acid as standard
and expressing the results as mg gallic acid equivalent / 100
g, after corrections for interfering substances. By the same
methodology, ascorbic acid content was determined (using
an ascorbic acid standard) and results were expressed in terms
of mg ascorbic acid/100 g (18).
For total carotenoid analyses, frozen fruits were thawed
and contents were assessed on the whole fruit (pulp and peel),
pulp, and seedless juice. Homogenized samples were mixed
with acetone for extraction of carotenoids. The liquid was then
filtered and concentrated, and the carotenoids were extracted
with ethylic ether/n-hexane (50/50, v/v). The organic phase
was dried under a nitrogen flow, and the remnant was
dissolved in ethylic ether and saponified by mixing with po-
tassium hydroxide. The organic phase was separated and the
aqueous phase was extracted again with ethylic ether/n-hex-
ane (50/50, v/v). The total organic phase was mixed with a
sodium chloride solution to eliminate alkali, and then sepa-
rated and dried under a nitrogen flow. A precise amount of
n-hexane was added to a portion of the remnant and absor-
bance was read at 450 nm with a UV-1700 Shimadzu UV-
visible spectrophotometer. Total content of carotenoids was
estimated by using the extinction coefficient of ß-carotene at
a 1% concentration in n-hexane (2500). The same sample was
used for identification of carotenoids, using a Hewlett Packard
1050 reverse-phase HPLC system coupled to a diode array
detector. The HPLC was equipped with a Spherisorb ODS-2
HP (250 mm × 4 mm × 5 μm) column. The mobile phase was
a mixture of acetonitrile, dichloromethane, and methanol
(82:13:5); flow rate was set at 1.5 mL / min; and the determi-
nation was performed at 20ºC. For identification of caro-
tenoids, only whole fruits were analyzed.
To identify the volatile compounds, frozen whole fruits
were thawed and aroma compounds were assessed on the
seedless pulp. Extracts were obtained by mixing 2 g of pulp
with 30 mL of pentane/ether (50/50, v/v) and then
homogenizing using a Potter Elvejhem homogenizer for 5 min
at room temperature. The organic phase was recovered, dried
with anhydrous sodium sulfate, and concentrated at 37ºC to 1
mL with a 25-cm Vigreux distillation column (19). GC-MS
analysis was used to identify volatile components using a
Hewlett-Packard 6890 gas chromatograph coupled to a
Hewlett-Packard 5973 quadrupole mass spectrometer. The
column was a DB-WAX fused silica capillary column (30 m,
0.32 mm i.d., 0.25 μm film thickness), preceded by a 2 m,
0.32 mm i.d. uncoated pre-column. Oven temperature was
set at 40ºC for 3 min, then increased to 245ºC at 3ºC/min, and
kept at this temperature for 20 min. The on-column injector
was heated from 20ºC to 245ºC at 180ºC/min. The detector
and injector temperatures were 250ºC. Helium was the carrier
gas at 1.1 mL / min. The electron impact energy was 70 eV
and the ion source and quadrupole temperatures were 230ºC
and 150ºC respectively. Electron impact (EI) mass spectra
were recorded in the 40-600 amu range at 1-s intervals.
Injection volume was 2 μL of extract. Volatile compounds
were identified by comparing their spectra with those of the
Wiley 275 and NIST MS libraries.
RESULTS
The chemical characterization of Costa Rican naranjilla
pulp, as well as results found in literature for ripe fruits from
Colombia and Ecuador are summarized in Table 1. When com-
paring results, factors such as sampling, plotting, sample
preparation, extraction, and measurement, besides genetic and
environmental factors (maturity, UV light exposure, etc.)
should be considered. Total antioxidant capacity of naranjilla
pulp was measured in terms of H-ORAC (Table 2). Total
polyphenolic and ascorbic acid content are reported as well.
Total carotenoid content was determined in naranjilla whole
fruits, pulp, and seedless juice (Table 3). Carotenoid identifica-
tion in naranjilla whole fruits is presented in Table 4, where ß-
carotene was the main carotenoid found. No carotenoid identi-
fication in naranjilla fruit has been previously reported. Using
GC-MS analysis, 10 volatile compounds were identified in
naranjilla pulp (Table 5). In this study, the predominant aroma
constituent found in the fruit’s pulp was methyl butanoate, a
volatile compound described as sweet and fruity.
DISCUSSION
Main characteristics
When compared with the characteristics of naranjilla fruits
from Colombia as reported by Arango et al (2), Romero (20),
and Guzmán et al (21), moisture content in the Costa Rican
fruits (Table 1) was lower, ash content higher, protein content
similar, fat content lower (no fat detected in Costa Rican
samples), sugar content higher (sucrose and glucose content
higher and fructose content lower compared with samples
analyzed by Guzmán et al [21]); and total soluble solids lower.
Compared with the Ecuadorian fruit characteristics reported
by Dávila (22), total soluble solids of Costa Rican fruits were
higher, pH was lower, total sugars were higher, and ash con-

91
CHEMICAL CHARACTERIZATION, ANTIOXIDANT PROPERTIES, AND VOLATILE CONSTITUENTS
NRNRNRNRNR40 ± 3Hunter parameter b*
NRNRNRNRNR7.8 ± 1.0Hunter parameter a*
NRNRNRNRNR40 ± 3Hunter parameter L*
NR8NRNR9.5 ± 0.59.1 ± 0.5
Total soluble solids
(ºBrix)
NR3.33.3NR3.1 ± 0.1
3.20 ±
0.04
pH
NR1.922.30NR3.65 ± 0.1
2.63 ±
0.07
Total titratable acidity
(g citric acid equivalent
/100g)
23NRNR232418 ± 2
b
Energy va lue (kc al/100 g)
0.61 - 0.80.540.880.80.7
0.92 ±
0.04
Ash (g / 100 g)
NRNR0.75NRNR0.7 ± 0.1Fructose (g / 100 g)
NRNR0.52NRNR
0.68 ±
0.05
Glu cose ( g / 100 g)
NRNR1.08NRNR1.6 ± 0.3Suc rose ( g / 100 g)
NR2.512.4NR2.91 ± 0.23.0 ± 0.4Sugars (g / 100 g)
0.3 - 4.6NR0.530.3NR1.4 ± 0.2Dietary fiber (g / 100 g)
5.7NRNR5.7NR
¦
3.8 ± 0.5
‡
Available carbohydrates
(g / 100 g)
0.1 - 0.24NR0.160.10.0001ND
*
Fat (g / 100 g)
0.107 - 0.6NR0.720.60.6 ± 0.10.7 ± 0.2Protein (g / 100 g)
85.8 - 92.590.6791.9592.592.290.6 ± 0.3Moisture (g / 100 g)
Colombia
and
Ecuador
(5)
Ecuador
(22)
Colombia
(21)
Colombia
(20)
Colombia
(2)
Costa RicaComponent
NRNRNRNRNR40 ± 3Hunter parameter b*
NRNRNRNRNR7.8 ± 1.0Hunter parameter a*
NRNRNRNRNR40 ± 3Hunter parameter L*
NR8NRNR9.5 ± 0.59.1 ± 0.5
Total soluble solids
(ºBrix)
NR3.33.3NR3.1 ± 0.1
3.20 ±
0.04
pH
NR1.922.30NR3.65 ± 0.1
2.63 ±
0.07
Total titratable acidity
(g citric acid equivalent
/100g)
23NRNR232418 ± 2
b
Energy va lue (kc al/100 g)
0.61 - 0.80.540.880.80.7
0.92 ±
0.04
Ash (g / 100 g)
NRNR0.75NRNR0.7 ± 0.1Fructose (g / 100 g)
NRNR0.52NRNR
0.68 ±
0.05
Glu cose ( g / 100 g)
NRNR1.08NRNR1.6 ± 0.3Suc rose ( g / 100 g)
NR2.512.4NR2.91 ± 0.23.0 ± 0.4Sugars (g / 100 g)
0.3 - 4.6NR0.530.3NR1.4 ± 0.2Dietary fiber (g / 100 g)
5.7NRNR5.7NR
¦
3.8 ± 0.5
‡
Available carbohydrates
(g / 100 g)
0.1 - 0.24NR0.160.10.0001ND
*
Fat (g / 100 g)
0.107 - 0.6NR0.720.60.6 ± 0.10.7 ± 0.2Protein (g / 100 g)
85.8 - 92.590.6791.9592.592.290.6 ± 0.3Moisture (g / 100 g)
Colombia
and
Ecuador
(5)
Ecuador
(22)
Colombia
(21)
Colombia
(20)
Colombia
(2)
Costa RicaComponent
tent was higher. Morton (5) reported results of analyses per-
formed on fresh naranjilla fruits in Colombia and Ecuador.
When compared with these results, Costa Rican fruits showed
moisture and fiber contents within the reported range, but they
had higher protein and ash, and lower fat content.
TABLE 1
Chemical characterization and color parameters of Costa Rican naranjilla pulp (data expressed on a fresh weight
basis and reported as mean ± standard deviation, n = 4 lots), and results reported in literature for ripe naranjilla
fruits from different locations
* ND = not detected. ‡ Determined by calculation. NR = not reported.
TABLE 2
H-ORAC value, total polyphenolic, and ascorbic acid
content in naranjilla pulp (data expressed on a fresh weight
basis and reported as mean ± standard deviation,
n = 4 lots except for ascorbic acid: n = 3)
Component Result
H-ORAC (μmol Trolox equivalent/g) 17 ± 1
Total polyphenolics (mg gallic acid equivalent/100 g) 48 ± 3
Ascorbic acid (mg/100 g)
12.5 ± 0.0
TABLE 3
Total carotenoid content of naranjilla whole fruits, pulp,
and seedless juice (data expressed on a fresh weight basis
and reported as mean ± standard deviation, n = 2 lots)
Sample Carotenoid content (μg / g)
Whole fruits 33.3 ± 0.6
Pulp 7.2 ± 0.3
Seedless juice 4.60 ± 0.08

92 ACOSTA et al.
TABLE 4
Carotenoid identification in naranjilla whole fruits
Carotenoid Retention Proportion of identified
time (min) carotenoids (%)
β-carotene 10.1 58.4
Lutein 3.4 32.2
Cis-β-carotene 11.0 6.1
Violaxanthin 2.2 3.2
Antioxidant properties
The H-ORAC value of naranjilla was higher than those of
banana, cantaloupe, honeydew, kiwi fruit, nectarine, pineapple,
and watermelon (among others); similar to those of red grape-
fruit, navel orange, peach, pears, and tangerine; but lower than
those of apples, cherry, plums, and all berries (Wu et al [23]).
Total polyphenolic content was similar to values found in ba-
nana, pineapple, and lemon (24). Ascorbic acid content was
lower than values reported by other authors, of 25 (20) and in
the range of 31.2-83.7 mg / 100 g (5). Authors have reported
contents of total vitamin C of 37.5 (21), 47.5 (22), and 95 mg
/ 100 g (2) for Colombian and Ecuadorian naranjilla samples.
Carotenoid content and identification
For Colombian and Ecuadorian naranjilla samples, Morton
(5) reported carotene contents of 0.71-2.32 μg / g and Guzmán
et al (21) indicated ß-carotene content among Colombian
naranjilla samples of 2.212 μg / g (in edible portion). Costa
Rican naranjilla seemingly had higher contents. However, to-
tal carotenoid content in the edible portion of naranjilla from
different locations was lower when compared with fruits with
high content (more than 20 μg / g), such as grapefruit, pa-
paya, and nectarine (25). Carotenoid content found in the
whole naranjilla fruit (pulp and peel) was similar or higher
than those found in vegetables with high total carotenoid con-
tent, such as kale, red paprika, and parsley (25). Carotenoid
content in naranjilla peel was higher than in its pulp, which
was noticeable when the colors of both parts were compared.
Carotenoid identification in naranjilla whole fruits indicate
that ß-carotene and lutein, two of five carotenoids on which
most nutrition research has focused (26), were predominant.
ß-carotene, the main carotenoid found in naranjilla, has pro-
vitamin A activity and can be converted in the body to retinol
(26). Epidemiologic reports suggest that the sum of lutein
and zeaxanthin, the retinal carotenoids forming the macular
pigment, had the strongest protective effect against
neovascular age-related macular degeneration, when dietary
intakes of different carotenoids were analyzed (27).
Grassy green and fruityNot found1.902-methyl-2-pentenal
Herbaceous, sweet,
tobacco-like, coumarinic
type
8.22.33γhexal act one
Fruity-winey<0.12.87
Methyl 3-
hydroxyhexanoate
Sharp and green-fruity0.93.40Met hyl ( E)-2-butenoate
Sweet, of pineapple-
apricot type
0.43.81Methyl hexanoate
Fruity, suggestive of
ban ana and pi neapple
26.74.02Ethyl butanoate
Pungent, heavy sweet,
deep-floral
0.35.75Methyl benzoate
Sour, reminiscent of
rancid butter
0.48.38Butanoic acid
Not reportedNot found13.25
4-hydroxy-4-methyl-2-
pentanone
Sweet, fruity12.154.30Methyl butanoate
Odor description (28)
Volatile compounds
identified by Brunke et al
(4) (area percent in
gas chrom ato gram s)
Proporti on of ident ifie d
volatile compounds (%)
Volatile compound
Grassy green and fruityNot found1.902-methyl-2-pentenal
Herbaceous, sweet,
tobacco-like, coumarinic
type
8.22.33γhexal act one
Fruity-winey<0.12.87
Methyl 3-
hydroxyhexanoate
Sharp and green-fruity0.93.40Met hyl ( E)-2-butenoate
Sweet, of pineapple-
apricot type
0.43.81Methyl hexanoate
Fruity, suggestive of
ban ana and pi neapple
26.74.02Ethyl butanoate
Pungent, heavy sweet,
deep-floral
0.35.75Methyl benzoate
Sour, reminiscent of
rancid butter
0.48.38Butanoic acid
Not reportedNot found
13.25
4-hydroxy-4-methyl-2-
pentanone
Sweet, fruity12.154.30Methyl butanoate
Odor description (28)
Volatile compounds
identified by Brunke et al
(4) (area percent in
gas chrom ato gram s)
Proporti on of ident ifie d
volatile compounds (%)
Volatile compound
TABLE 5
Volatile compounds identified in naranjilla pulp

93
CHEMICAL CHARACTERIZATION, ANTIOXIDANT PROPERTIES, AND VOLATILE CONSTITUENTS
Volatile compounds
In a previous study, Brunke et al (4) identified 59 compo-
nents in a solvent extract (80/20, v/v of ether/pentane) of
Ecuadorian naranjilla fruit juice after silica gel flash chroma-
tography. Authors also sensorially characterized compounds
by sniffing GC. From the list of compounds that Brunke et al
(4) identified, with concentrations higher than 0.9% (reported
as area percent in gas chromatograms), only ethyl acetate,
3-methylbutyl acetate, ethyl (E)-2-butenoate, ethyl
3-hydroxybutanoate, ethyl 3-hydroxyhexanoate, ethyl
3-acetoxyhexanoate, linalool, and acetic acid were not found
in the present study. All of the compounds found in Costa
Rican samples were also reported by Brunke et al (4), except
for 2-methyl-2-pentenal and 4-hydroxy-4-methyl-2-
pentanone.
CONCLUSION
The chemical characteristics of samples of naranjilla (S.
quitoense Lam.) fruits cultivated in Costa Rica were analyzed.
The fruits exhibited a chemical composition similar to those
previously reported in different locations. Information on
chemical composition, antioxidant properties, and volatile
constituents may increase this crop’s value in local and re-
gional markets as a fresh fruit and as raw material for pro-
cessed products.
ACKNOWLEDGMENTS
The authors thank M. Torres, J. Bustos, Y. Chan, and E.
Murillo for their technical assistance. They are likewise grate-
ful to Helénica Proverde S. A., the French agency AIRE
Développement (grant no. 01-8-CR-27-2), and Ministerio de
Ciencia y Tecnología, Comisión de Incentivos para la Ciencia
y la Tecnología, Consejo Nacional para Investigaciones
Científicas y Tecnológicas (CONICIT), Fondos PROPYME
no. FP-009-04 (San José, Costa Rica) for their valuable finan-
cial help.
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Recibido: 30-09-2008
Aceptado: 15-01-2009