Using Guava Leaf Essential Oils to Enhance the Aroma Quality of Guava Juice
Hsin-Chun Chen1, Ming-Jen Sheu1, Li-Yun Lin2, Chung-May Wu2
1
National Taiwan University, Taiwan (ROC); 2Hungkuang University, Taiwan
(ROC)
ABSTRACT
Guava juice was the most important traditional fruit juice in Taiwan before
commercial orange juice was imported from other countries. Guava is also known as
a fruit can improve glucose level with type 2 diabetes. This study reports using
essential oils obtained from guava leaves to enhance the aroma quality of guava
juice, aiming to improve the market share of this traditional fruit juice and also to
benefit the patients.
Leaf essential oils of six cultivars of guavas were obtained by steam distillation, the
yields of essential oils were: Chung-Shan Bar, 1.83±0.40 g/kg; Shih-Chi Bar,
1.25±0.33 g/kg; Li-Tzy Bar, 1.38±0.35 g/kg; Red Bar, 1.50±0.38 g/kg; Jen-Ju Bar,
1.03±0.25 g/kg and Shuei-Jing Bar, 1.08±0.28 g/kg, respectively. Essential oils were
then analyzed by capillary Gas Chromatography (GC) and Mass Spectrometry (MS).
Six essential oils were compared for their constituents. Totally 78 compounds were
identified, including 40 terpene hydrocarbons, 15 terpene alcohols,
and also minor
constituents of 3 alcohols, 4 aldehydes, 4 esters, 5 terpene esters, 2 terpene oxides,
2 heterocyclic furans, 1 terpene ketone, 1 ketone and 1 sulfur compound for the
species of Chung-Shan, this is the most suitable cultivar for the commercial juice.
The constituents of leaf essential oils are similar to guava fruits volatiles. Therefore,
nature leaf essential oils were used to enhance the aroma quality of guava juice
effectively.
Keywords: Guava, Guava juice, essential oil, Aroma
INTRODUCTION
Guava (Psidium guajava L.) is an important cultivated species of the Myrtle family.
Guava juice was the most important traditional fruit juice in Taiwan before
commercial orange juice was imported from other countries. In Taiwan and China,
the guava leaf has been used as a traditional therapy for dysentery, diabetes and
1
acute and chronic intestinal-inflammation (1). This study reports using essential oils
obtained from guava leaves to enhance the aroma quality of guava juice, aiming to
improve the market share of this traditional fruit juice and also to benefit the patients.
MATERIALS AND METHODS
Guava leaf material. The fresh leaves of Psidium guajava L. were obtained from
locally.
Sample preparation. The leaves (400g) were prepared by blending guava leaves
for 3 min with 2L of deionized water in a blender and put into a 5L round-bottom flask.
Leaves were steam-distilled for 2hr obtain the leaf essential oils.
GC analysis. Qualitative and quantitative analyses of the volatile compounds
were carried out using an Angilent 6890 gas chromatograph (GC) equipped with a
60m × 0.25 mm i.d. DB-1 fused-silica capillary column and a flame ionization
detector (FID). Injector and detector temperatures were both 250℃. Oven
temperature was held at 40℃ for 1 min and then raised to 150 ℃ at 5 ℃/min and
held for 1 min, finally raised to 200℃ at 10℃/min and held for 11 min. Carrier gas
(nitrogen) flow rate was 1mL/min. Sample injection volumn was1.0 µL with a split
ratio of 1/100. Kovats indices were calculated for separated components relative to a
C5-C25 n-alkanes (Alltech Associates, Inc.) mixture (2).
GC-MS analysis. Qualitative analyses of the volatile compounds were carried out
using an Angilent 6890 gas chromatograph (GC) equipped with 60 m × 0.25 mm i. d.
DB-1 fused-silica capillary column and an Agilent model 5973 N MSD mass
spectrometer (MS). Injector and detector temperatures were both at 250℃. The GC
conditions in GC-MS analysis were the same as GC analysis described above.
Carrier gas (helium) flow rate was 1 mL/min. The temperature of the ion source was
150℃. The electron energy was 70 eV. The constituents were identified by matching
their spectra with those recorded in the MS library (Wiley 7n).
Sensory Evaluation.
A preference analysis panel evaluated the flavor attributes
of the guava juice samples. The panel consisted of nine panelists recruited from
students at Hungkuan University. Samples included natural juice, juice with added
guava flavor and juice with added guava flavor plus leaf essential oil. Grade on
guava juice odor and preference value separately, grading system of it as:
Guava juice odor value: 9- very strong, 7- strong, 5- ordinary, 3- weak, 1 - very weak
2
Preference value: 9 – like very much, 7- like, 5- ordinary, 3 - like, 1- hate
RESULTS AND DISCUSSION
Leaf essential oils of six cultivars of guavas were obtained by steam distillation, the
yields of essential oils were: Chung-Shan Bar, 1.83±0.40 g/kg; Shih-Chi Bar,
1.25±0.33 g/kg; Li-Tzy Bar, 1.38±0.35 g/kg; Red Bar, 1.50±0.38 g/kg; Jen-Ju Bar,
1.03±0.25 g/kg and Shuei-Jing Bar, 1.08±0.28 g/kg, respectively. Essential oils were
then analyzed by capillary Gas Chromatography (GC) and Mass Spectrometry (MS).
Six essential oils were compared for their constituents. Totally 78 compounds were
identified. The major constituents identified in the essential oils of Chung-Shan Bar
and Shih-Chi Bar were α-pinene (14.94 ±0.27%, 10.69 ± 0.40%); 1,8-cineole (12.57
± 0.37%, 9.91 ± 0.35%) and β-caryophyllene (29.74 ± 0.36%, 32.04 ± 1.30%),
respectively. The essential oils of Li-Tey Bar and Red Bar were dominated by
1,8-cineole (10.38 ± 0.21%, 6.29 ± 0.30 %); β-caryophyllene (37.19 ± 0.75%, 32.33 ±
0.32%); aromadendrene (7.43 ± 0.30%, 11.73 ± 0.09%), respectively. The main
components found in the essential oil of Jen-Ju Bar were caryophyllene oxide (5.32 ±
0.15%), α-copaene (9.19 ± 0.20%), β-caryophyllene (43.74 ± 0.87%). The essential
oil of Shuei-Jing Bar was dominated by α-copaene (9.21 ± 0.21%), β-caryophyllene
(45.39 ± 0.61%), aromadendrene (5.18 ± 0.17%) (Table1, Fig2). The terpene
hydrocarbons constituted the major fractions of six cultivars leaf essential oils. The
principal compounds is β-caryophyllene for all six cultivars. Comparison of other
Psidium leaf oils previously reported with this report, we can find the oils of P.
guajava (3). P. cattleianum (4) , P. friedrichsthalianum (4), and P. striatulum (5) were
also dominated byβ-caryophyllene. Previous investigations about P. guajava L. have
reported the abundance of 1,8-cineole (5,6), α-pinene (5,6), limonene (7),
β-caryophyllene (3,7), β-bisabolene (3,5), aromadendrene (3), β-selinene (3),
nerolidiol (3), caryophyllene oxide (3) and sel-11-en-4α-ol (3). However, the
qualitative and quantitative variations between the present results and those from
other parts of the world may be attributable to the differences in ecological and
climatic conditions between Taiwan and the other countries.
Sensory evaluations showed that nature leaf essential oils were used to enhance the
aroma quality of guava juice effectively.
3
2 .5
Essential Oil Content (g/kg)
2 .0
1 .5
1 .0
0 .5
0 .0
A
B
C
D
E
F
G u a v a c u ltiv a r s
Fig1. Guava leaves essential oil yield （A: Chung-Shan Bar; B: Shih-Chi Bar; C:
Li-TzyBar; D: Red Bar; E: Jen-Ju Bar; F: Shuei-Jing Bar).
50
40
(%)
30
α - p in e n e
1 ,8 - c in e o le
α -c o p a e n e
β - c a r y o p h y lle n e
a ro m a d re n d re n e
c a r y o p h y lle n e o x id e
20
10
0
A
B
C
D
E
F
G u a v a le a f c u ltiv a r s
Fig 2. Major volatile flavor compounds amounts from six cultivars of guavas leaf
essential oils (A: Chung-Shan Bar; B: Shih-Chi Bar; C:Li-Tzy Bar; D:Red Bar;
E：Jen-Ju Bar; F: Shuei-Jing Bar).
4
Table1. Comparisons of Analysis of Guava Leaf Essential Oils by Direct Inject GC
compound
Aliphatic Sulfur compounds
dimethyl sulfide
dimethyl disulfide
Chung-Shan Bar Shih-Chi Bar
BC
DI-GC
DI-GC
tre
Aliphatic Alcohols
3-hexen-1-ol
2-hexen-1-ol
1-hexen-1-ol
0.25±0.01
0.03±0.003
0.05±0.01
Aliphatic Aldehydes
hexanal
2-hexenal
heptanal
Benzaldehyde
0.05±0.004
0.22±0.01
0.01±0.001
0.01±0.003
Aliphatic Esters
3-hexenyl acetate
hexyl acetate
3-hexenyl 2-methylbutyrate
3-hexenyl hexanoate
0.03±0.01
tr
0.02±0.002
tr
Li-Tzy Bar
Red Bar
Jen-Ju Bar
Shuei-Jing Bar
DI-GC
DI-GC
DI-GC
DI-GC
tr
tr
0.35±0.02
0.47±0.02
0.24±0.03 0.39±0.003
0.03±0.03
0.09±0.01 0.04±0.003
0.06±0.01
0.11±0.02 0.17±0.005
0.13±0.01
0.25±0.02
0.02±0.01
0.06±0.01
0.18±0.02
0.01±0.004
tr
tr
0.10±0.01
0.49±0.02
tr
0.23±0.01
0.08±0.02
0.47±0.03
tr
0.04±0.01
0.09±0.02
0.16±0.01
0.05±0.01
0.06±0.01
tr 0.02±0.007
tr 0.01±0.002
0.02±0.01 0.01±0.001 0.02±0.001
tr
0.05±0.01
0.01±0.001
0.01±0.007
5
0.20±0.04
0.07±0.01
0.38±0.03
0.42±0.01
tr 0.01±0.006
tr
0.64±0.02
Table1. (continued).
compound
Chung-Shan Bar Shih-Chi Bar
DI-GC
DI-GC
Aliphatic Ketones
6-methyl-5-hepten-2-one
0.04±0.001
0.07±0.01
Terpene Alcohols
fenchyl alcohol
trans-pinocarveol
borneol
1,8-menthadien-4-ol
4-terpineol
0.02±0.01
0.09±0.01
0.01±0.001
0.01±0.002
0.21±0.02
Terpene Alcohols
α-terpineol
nerolidol
epiglobalol
spathulenol
globulol
ledol
α-cadinol
caryophyllenol
linalool
farnesol
1.15±0.11
4.73±0.15
0.53±0.03
3.98±0.07
1.58±0.03
0.63±0.03
0.44±0.01
0.09±0.01
0.03±0.001
Li-Tzy Bar
Red Bar
DI-GC
DI-GC
Jen-Ju Bar Shuei-Jing Bar
DI-GC
DI-GC
0.05±0.01 0.06±0.001 0.01±0.005
0.01±0.001
0.04±0.01
0.19±0.02
0.03±0.005 0.02±0.007
0.15±0.01
0.09±0.01
0.04±0.01
0.02±0.005
0.03±0.01
0.98±0.02
5.73±0.10
0.76±0.06
0.65±0.02
3.37±0.17
0.88±0.05
0.34±0.01
3.44±0.15
0.62±0.02
0.70±0.04
0.42±0.02
0.07±0.01
0.55±0.02
0.08±0.02
2.77±0.16
1.63±0.05
0.68±0.07
0.92±0.05
0.13±0.02
6
0.43±0.02
0.08±0.01
4.05±0.22
4.27±0.06
1.63±0.19
0.76±0.03
0.33±0.01
0.63±0.04
5.59±0.02
2.67±0.06
2.01±0.04
2.73±0.11
0.44±0.02
0.55±0.04
0.53±0.02
0.93±0.06
0.07±0.01 0.03±0.005
0.31±0.04
0.09±0.01
0.12±0.01
3.85±0.02
0.76±0.02
0.55±0.03
2.86±0.13
1.84±0.11
0.51±0.02
0.35±0.04
0.02±0.01
0.43±0.04
Table1. (continued).
compound
Chung-Shan Bar Shih-Chi Bar
DI-GC
Terpene Esters
fenchyl acetate
bornyl acetate
neryl acetate
geranyl acetate
benzyl benzoate
0.01±0.004
0.01±0.004
0.02±0.001
0.11±0.01
0.01±0.004
Terpene Ketones
pinocarveone
0.02±0.01
Terpene Oxides
1,8-cineole
caryophyllene oxide
12.57±0.37
3.00±0.09
Terpene Hydrocarbons
styrene
α-thujene
α-pinene
α-fenchene
camphene
tr
0.06±0.01
14.94±0.27
0.01±0.002
0.03±0.01
DI-GC
Li-Tzy Bar
Red Bar
Jen-Ju Bar
Shuei-Jing Bar
DI-GC
DI-GC
DI-GC
DI-GC
0.01±0.006 0.06±0.003
0.01±0.005
0.02±0.01 0.04±0.003
0.07±0.01
0.21±0.01
0.04±0.01 0.01±0.005
tr 0.01±0.002
0.04±0.01
0.03±0.01
0.11±0.03
0.15±0.01
6.29±0.30
2.48±0.16
0.56±0.01
5.32±0.15
2.12±0.07
2.59±0.12
0.01±0.01 0.01±0.005 0.01±0.006 0.01±0.002
0.27±0.03 0.01±0.002
0.03±0.01 0.01±0.003
10.69±0.41
0.67±0.02
0.21±0.03
0.17±0.05
0.01±0.003
0.03±0.01
tr
0.05±0.01
0.43±0.03
0.02±0.01
9.91±0.35 10.38±0.21
6.09±0.11
3.92±0.37
7
Table1. (continued).
compound
Terpene Hydrocarbons
β-pinene
β-myrcene
1-phellandrene
α-terpinene
ρ-cymene
limonene
β-ocimene
r-terpinene
α-dimethyl styrene
α-terpinolene
alloocimene
neoalloocimene
α-cubebene
α-Muurolene
cyclosativene
α-copaene
isocaryophyllene
α-gurjunene
β-caryophyllene
calarene
Chung-Shan Bar Shih-Chi Bar
DI-GC
0.37±0.03
0.36±0.04
0.03±0.01
0.05±0.01
0.10±0.01
0.28±0.04
0.24±0.03
tr
0.06±0.01
0.02±0.002
0.02±0.08
0.01±0.001
0.09±0.01
4.03±0.32
0.43±0.01
29.74±0.36
0.40±0.02
DI-GC
Li-Tzy Bar
Red Bar
Jen-J uBar
Shuei-Jing Bar
DI-GC
DI-GC
DI-GC
DI-GC
0.32±0.02
0.05±0.01
0.04±0.01 0.01±0.002
0.28±0.03
0.20±0.03
0.15±0.02
0.07±0.01
0.03±0.002 0.03±0.003
0.03±0.01 0.01±0.003
0.05±0.01
0.04 0.04±0.001 0.01±0.002
0.11±0.02 0.06±0.005
0.06±0.01 0.02±0.005
tr
1.54±0.10
0.34±0.02
0.20±0.02
0.30±0.03
0.13±0.01
0.21±0.03
0.17±0.02
0.10±0.01 0.03±0.004
0.02±0.003
0.07±0.02
0.05±0.01 0.03±0.003
0.04±0.01 0.02±0.004
0.03±0.01
0.02±0.01
0.04±0.01
tr
0.02±0.005 0.01±0.001 0.01±0.001
0.17±0.03 0.07±0.001
0.15±0.01
0.44±0.01
0.02±0.004 0.01±0.002
0.14±0.01
0.12±0.02
0.16±0.01
6.11±0.07
1.87±0.05
5.29±0.11
9.19±0.20
0.14±0.02
0.18±0.01
0.12±0.01
0.36±0.03
0.49±0.03
0.68±0.04
0.32±0.01
32.04±1.30 37.19±0.75 32.33±0.32 43.74±0.87
0.25±0.01
0.86±0.03
0.79±0.02
0.22±0.01
8
0.03±0.01
0.08±0.01
0.02±0.01
0.02±0.007
0.02±0.003
0.11±0.01
0.05±0.01
tr
0.03±0.005
tr
tr
0.57±0.01
0.02±0.001
0.15±0.03
9.21±0.21
0.10±0.01
0.36±0.03
45.39±0.61
0.24±0.03
Table1. (continued)
compound
Chung-Shan Bar Shih-Chi Bar
DI-GC
DI-GC
6.60±0.30
3.09±0.04
1.35±0.03
0.60±0.02
4.66±0.44
3.22±0.02
1.37±0.01
0.68±0.04
0.08±0.01
0.03±0.003
1.22±0.11
0.86±0.04
Li-Tzy Bar
Red Bar
Jen-J uBar Shuei-Jing Bar
DI-GC
DI-GC
DI-GC
DI-GC
7.43±0.30 11.73±0.09
3.72±0.06
3.35±0.12
1.75±0.01
2.36±0.05
0.85±0.06
1.27±0.07
0.13±0.02
0.10±0.02
0.10±0.02
7.45±0.31
4.57±0.10
7.03±0.09
3.38±0.17
0.31±0.04
0.85±0.04
4.84±0.08
4.40±0.06
1.80±0.04
1.36±0.05
0.13±0.01
0.05±0.01
1.28±0.02
1.38±0.03
5.18±0.17
4.49±0.20
1.84±0.03
1.52±0.11
0.06±0.02
1.49±0.13
0.56±0.71
1.84±0.16
1.72±0.06
3.21±0.04
2.32±0.03
0.03±0.01
0.44±0.03
1.29±0.06
3.85±0.12
2.37±0.07
Terpene Hydrocarbons
aromadendrene
α-humulene
alloaromadendrene
α-amorphene
zingiberene
β-selinene
α-bisabolene
β-bisabolene
γ-Bisabolene
calamene
δ-cadinene
caddina-1,4 diene
α-selinene
γ-gurjunene
β-himachalene
Heterocyclic Furan
2-ethyl furan
2-pentyl furan
a
1.67±0.07
1.64±0.11
0.23±0.02
2.17±0.12
1.25±0.04
3.04±0.04
1.00±0.03
0.37±0.02
0.05±0.004
0.46±0.01
0.64±0.02
0.49±0.04
0.01±0.001
tr
0.01±0.004 0.01±0.001 0.01±0.002 0.01±0.003
tr
tr
tr
Name of guava species cultivated in Taiwan.
e
0.72±0.01
2.25±0.02
1.08±0.05
0.30±0.03
b
Analyzed by SPME-GC method.
c
0.35±0.03
0.06±0.004
Analyzed by Direct Injection GC（DI-GC）method.d undetectable
tr. less than 0.01﹪ f Unit is each peak percentage to total peaks percentage, average and standard deviation, average of three experiments.
9
tr
tr
CONCLUSIONS
Leaf essential oils of six cultivars of guavas were obtained by steam distillation, the
yields of essential oils were: Chung-Shan Bar, 1.83±0.40 g/kg; Shih-Chi Bar,
1.25±0.33 g/kg; Li-Tzy Bar, 1.38±0.35 g/kg; Red Bar, 1.50±0.38 g/kg; Jen-Ju Bar,
1.03±0.25 g/kg and Shuei-Jing Bar, 1.08±0.28 g/kg, respectively. The major
constituents identified in the essential oils of Chung-Shan Bar and Shih-Chi Bar were
α-pinene (14.94 ±0.27%, 10.69 ± 0.40%); 1,8-cineole (12.57 ± 0.37%, 9.91 ± 0.35%)
and β-caryophyllene (29.74 ± 0.36%, 32.04 ± 1.30%), respectively. The essential oils
of Li-Tey Bar and Red Bar were dominated by 1,8-cineole (10.38 ± 0.21%, 6.29 ±
0.30 %); β-caryophyllene (37.19 ± 0.75%, 32.33 ± 0.32%); aromadendrene (7.43 ±
0.30%, 11.73 ± 0.09%), respectively. The main components found in the essential oil
of Jen-Ju Bar were caryophyllene oxide (5.32 ± 0.15%), α-copaene (9.19 ± 0.20%),
β-caryophyllene (43.74 ± 0.87%). The essential oil of Shuei-Jing Bar was dominated
by α-copaene (9.21 ± 0.21%), β-caryophyllene (45.39 ± 0.61%), aromadendrene
(5.18 ± 0.17%).
Nature leaf essential oils were used to enhance the aroma quality of guava juice
effectively.
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11