Changes of Volatile Compounds and Physicochemical ... - CRDC

Agricultural Sci. J. 42(2)(Suppl.): 109-112 (2011) ว. วิทย์. กษ. 42(2)(พิเศษ): 109-112 (2554)
การเปลี ยนแปลงสารหอมระเหยและคุณภาพทางเคมี กายภาพของส้มโอตัดแต่งระหว่างการเก็บรักษา
Changes of Volatile Compounds and Physicochemical Qualities of Fresh Cut Pomelo During Storage
อรัญญา นิพนธ์ศักดิ 1 ณัฎฐา เลาหกุลจิตต์1 และ อรพิน เกิดชูชื น 1
Niponsak, A. 1 , Laohakunjit, N. 1 and Kerdchoechuen, O. 1
Abstract
Volatile compounds and physicochemical qualities of fresh cut pomelo are important for consumer
acceptance. This research was to evaluate the volatile compounds changes and physicochemical qualities;
volatile compounds, pH, titratable acidity, % total soluble solid ( o Brix), sugar content, fruit colour and firmness
of fresh cut pomelo cv. Khao yai during storage under ambient conditions (25 o C+3). Three main volatile compounds
were found in fresh cut pomelo during storage. Although cyclopentyl-4-ethylbenzoate was increased
during storage, δ- cadinene and β caryophyllene were increased at the first stage of three days and decreased
at the end of four days storage. Fresh cut pomelos were more lighten (L*) than the control but a* (redness)
was decreased while b* (yellowness), hue and chroma were stable during storage. Moreover, fruit firmness,
pH and sucrose content slowly decreased during the storage conditions but %titratable acidity, fructose
and glucose content slightly increased.
Keywords: pomelo, volatile compounds, physicochemical qualities, storage
บทคัดย่อ
สารหอมระเหยและคุณภาพทางเคมี-กายภาพของส้มโอตัดแต่งมีความสําคัญต่อการเลือกซื อของผู ้บริโภค ดังนั น
งานวิจัยนี จึงศึกษาการเปลียนแปลงของสารหอมระเหยและคุณภาพทางเคมี-กายภาพของส้มโอตัดแต่งพันธุ ์ขาวใหญ่ระหว่าง
การเก็บรักษาทีอุณหภูมิห้อง (25 o C+3) คุณสมบัติทางเคมีได้แก่ สารหอมระเหย pH ความเป็ นกรด ปริมาณของแข็งทั งหมด
( o Brix) ปริมาณและชนิดนํ าตาล ส่วนคุณสมบัติทางกายภาพ ได้แก่ ค่าสี และ ค่าความแน่นเนื อ พบการเปลียนแปลงของสาร
หอมระเหยหลัก 3 ชนิดในส้มโอตัดแต่งสด โดย cyclopentyl-4-ethylbenzoate มีปริมาณเพิมขึ นในระหว่างการเก็บ ขณะที
δ- cadinene และ β-caryophyllene เพิมขึ นวันที 1 ถึงวันที 3 และลดลงเมือสิ นสุดระยะเวลาการเก็บในวันที 4 ในระหว่าง
การเก็บรักษา ค่าความสว่างของส้มโอตัดแต่งเพิมขึ น ค่าความเป็ นสีแดงลดลง ส่วนค่าความเป็ นสีเหลือง hue angle และ
chroma ไม่เปลียนแปลง ค่าความแน่นเนื อ pH และปริมาณซูโครสค่อยๆ ลดลง แต่ค่าความเป็ นกรด ปริมาณนํ าตาลฟรุกโตส
และกลูโคสเพิมขึ น
คําสําคัญ: ส้มโอ สารหอมระเหย คุณภาพทางเคมี-กายภาพ การเก็บรักษา
Introduction
Pomelo is an economically important fruit in Thailand. The pomelo is a non-climacteric fruit which contains
rich of nutritions such as vitamin C, potassium, phosphorus, folic acid, citric acid, etc. (Igual et al., 2010).
The flavour of pomelo is mild, not sour like a grapefruit and sweet as an orange but pomelo is difficultly eaten
and difficultly observed senescence in whole fruits. Thus, minimally process or fresh cut pomelo is developed
but storage period of pomelo is not detected. Fruit storage involves many physicochemical qualities changes
which influence on the consumer satisfaction. Flavour studies in different fruit samples have been of increasing
interests due to their relationship with quality. As a result, there are many researches of volatile compound
changes of whole fruit during storage such as apricot (Gonzalez et al., 2009), pineapple (Umano et al., 1992)
and pomelo (Phaungsombut et al., 2008). Although previous work on the quality of pomelo in the whole fruit
had been studied, the monitoring of chemical and physical qualities in fresh cut pomelo during storage has
1
คณะทรัพยากรชีวภาพและเทคโนโลยี มหาวิทยาลัยเทคโนโลยีพระจอมเกล้าธนบุรี 49 ซ.เทียนทะเล 25 แขวงท่าข้าม เขตบางขุนเทียน กรุงเทพ 10150
1
School of Bioresources and Technology, King Mongkut’s University of Technology Thonburi, 49 Soi Tientalay 25, Thakam, Bangkhuntein, Bangkok 10150

110 ปี ที 42 ฉบับที 2 (พิเศษ) พฤษภาคม - สิงหาคม 2554 ว. วิทยาศาสตร์เกษตร
lack of information. The objective of this research was to report the volatile compounds and physicochemical
changes in pomelo cv.Khao yai during storage at ambient conditions.
Materials and Methods
Plant materials preparation: Pomelo (Citrus maxima) cv. Khao yai was harvested at 100% maturity and transported
from the orchard to the laboratory. Fruits were selected for uniformity in size (1.6 -1.9 kg) and colour. After
that, fresh pomelo pulps were taken out from the fruit. The pulps were placed on polystyrene trays and wrapped
with a commercially film. Fruits were packaged and kept at an ambient temperature of 25 o C + 3. Volatile compound,
colour, fruit firmness, pH, %titratable acidity, total soluble solid and sugar content were measured every
day and all analyses were performed in three replicates. Analysis of variance (ANOVA) and Duncan’s multiple
range test (DMRT) were performed using the SAS Program Version 6.0 (SAS Institute, 1997,USA)
Isolation of volatile compounds using headspace-solid-phase microextraction gas chromatography (HS-SPME-
GC-MS): A 50/30µm DVB/CAR/PDMS fiber was used in this study. Five milliliters of pomelo juice were transferred
into a 30 ml vial. Juice samples were placed in a vial heater at 40 o C 10 min. Sampling time was 45 min
at 40 o C. Desorption temperature at the GC injection port was 220 o C for 5 min. Juice sample was analyzed using
7890A GC-MS(DB-WAX column, 30m x 0.25mm x 0.25µm) and the temperature program was: 40 o C, then
40 o C to 240 o C at rate 4 o C min -1 , and held at 240 o C for 5 min. The splitless was applied. Mass spectra were
collected at a rate of 30 spectra/s over a range of m/z 33–500. The ionization energy was 70 eV. Data was
identified according to NIST v2.0 library and Wiley. Compounds were then confirmed by GC retention time (RT)
and MS spectra. The RTs from a series of aliphatic alkanes (C 8 –C 20 ) were used to calculate retention indices
(RIs) for all identified compounds.
Colour assessment and Fruit firmness: The colour change of pomelo pulp in ambient conditions was determined
by a Hunter Lab Colorimeter. Fruit pulps colour was recorded using the CIE-L*, a*, b*, hue angle and
chroma values. Fruit firmness of fruit was measured by Texture analyzer, fitted with a 10 mm cylindrical probe
to the probe carrier. The test was carried out at the probe speed of 1 mm/s to compress the fruit for 3 mm from
the contact point. A 250 N load cell was used. The force was recorded in kilogramforce.
pH and titratable acidity: Pomelo pulps were squeezed to pomelo juice. The pH of pomelo juice was measured
using an electrode pH meter. After pH determination, the juice was added by some drops of phenolphtaleine
as indicator solution and titrated against 0.1N NaOH to end point of pH 8.1. The juice acidity was expressed as
gram of citric acid (g citric acid/1 g fresh weight).
Total soluble solid: Pomelo pulps were squeezed to pomelo juice. Total soluble solid of samples were measured
using a hand refractrometer. Total soluble solid determination to give o Brix at 25 o C.
Determination of sugars content: The fruit juice (7 ml) was filtered through filter paper whatman#1 by vacuum
pump, and then centrifuged at 6,000 x g for 20 min. Supernatant was filtered through a 0.45-µm Millipore filter
and frozen at -18 o C until sugars before analysis. Sugar content (glucose, fructose, sucrose) was analyzed by
HPLC following method from Kelebek (2010) with the column of LiChrospher® 100 NH 2 and RI detector was
used for sugar analysis. The mobile phase was 86% acetronitrile/de-ionized water with the flow rate of 1.5 ml
min -1 . Sugars content in each sample were identified and quantified by external standard method using a
commercial standard of sucrose, glucose, and fructose.
Results and Discussion
In order to evaluate aroma changes under ambient conditions, Table 1 shows 34 volatile compounds
were identified in pomelo which odor description gave wood, citrus, herb, green and floral odor description during
storage. The major volatile compounds in fresh pomelo were 3 compounds, cyclopentyl-4-ethylbenzoate
increased during storage, δ-cadinene and β-caryophyllene were increased at three days and decreased at the

ว. วิทยาศาสตร์เกษตร ปี ที 42 ฉบับที 2 (พิเศษ) พฤษภาคม - สิงหาคม 2554 111
end of storage. Amounts of other terpene compounds, such as α-ylangene, germacrene D and aromadendrene
were rather different from the other citrus fruit varieties. When storage pomelo at room temperature for four days,
it found that volatile compounds, which gave wood, citrus, herb and floral odor, were decreased. While volatile
compounds, gave musty, green, and earthy odor, were increased. The most other volatile compounds increased
during storage because harvested fruits are living tissues and continue to respire and loss water in transpiration.
PVC film wrap has good gas permetration rate so the living tissue of pomelo can use oxygen to produce
terpenoid by mevalonic acid pathway (Perez et al., 1992) or alcohol, aldehyde, acid and ester produce by
oxidation reduction pathway (Umano et al., 1992). But some volatile compound decreased, it may be use degradation
pathway. When storage of pomelo at room temperature, fruit pulps were more lighten (L*) than the day 1
as same hue angle, a* was decreased but b* and chroma were not changed (Table 2). Similar trend was also
reported by Singh and Reddy (2006). Fruit firmness of fresh cut pomelo was diminished significantly under
ambient at the end of 4 days of storage might be due to the action of pectic enzymes and weight loss during fruit
transpiration. The trend is in agreement with the results reported by Muramatsu et al. (1996). pH generally decreased
but acidity increased with storage period under ambient temperature (Table 3). However, total soluble
solid was not changed under ambient storage. Fructose and glucose slightly increased in the 4 days of storage.
The sucrose reduced in pomelo stored under ambient might be attributed to the change in sucrose to fructose
and glucose due to the monosaccharides being used in the respiration process during storage. The trend in
sucrose reduced of pomelo with storage period was in agreement with Perez et al. (1992).
Summary
This study demonstrates that the volatile compounds and physicochemical qualities of fresh cut
pomelo changes can use for indicating the quality and storage period of fruit. Fresh cut pomelo has shelf life
for 3 days at 25 o C. After 3 days of storage, pomelo pulps have 6-methyl-5-hepten-2-ol, 3-methylpentanol,
1-octen-3-ol and heptanol which they gave musty odor description, and it is consistent with sensory evaluation
by fifteen panelists (data not show), colour, texture and chemical quality was changed. The data of this study
obtained can be used for decision of consumer.
Acknowledgements
This research was supported by a grant from The Royal Golden Jubilee Ph.D Program.
Literature cited
Gonzalez-Aguero, M., Troncoso, S., Gudenschwager, O., Campos-Vargas, R., Moya-Leon, M.A. and Defilippi,
B.G., 2009, Differential Expression Levels of Aroma-Related Genes During Ripening of Apricot (Prunus
armeniaca L.), Plant Physiology and Biochemistry, 47: 435–440.
Igual, M., Martinez, E.G., Camacho, M.M. and Navarrete, N. M., 2010, Effect of Thermal Treatment and Storage on
the Stability of Organic acids and the Functional value of Grapefruit juice, Food Chemistry, 118: 291–299.
Kelebek, H., 2010, Sugars, Organic acids, Phenolic Compositions and Antioxidant Activity of Grapefruit (Citrus
paradisi) Cultivars grown in Turkey, Industrial Crops and Products, 32: 269–274.
Muramatsu, N., Kiyohide, K. and Tatsushi, O., 1996, Relationship between Texture and Cell wall Polysaccharides
of Fruit Flesh in Various Species of Citrus, Horticulture Science, 31(1): 114–116.
Perez, A.G., Rios, J.J., Sanz, C. and Olias, J.M., 1992, Aroma Components and Free Amino Acids in Strawberry
Variety Chandler During Ripening, Journal of Agricultural and Food Chemistry, 40: 2232-2235.
Phaungsombut, A., Pathaveerat, S. and Terdwongworaku, A., 2008, Maturity Assessment of Pomelo Based on
Impact Method, Agricultural Science Journal, 39(3)(Suppl.): 27-30.
Singh, K.K. and Reddy, B.S., 2006, Post-Harvest Physico-Mechanical Properties of Orange peel and Fruit,
Journal of Food Engineering, 73: 112–120.

112 110 ปี ที 42 ฉบับที 2 (พิเศษ) พฤษภาคม - สิงหาคม 2554 ว. วิทยาศาสตร์เกษตร
Umano, K., Hagi, Y., Nakahara, K., Shoji, A. and Shibamoto, T., 1992, Volatile Constituents of Green and Ripened
Pineapple (Ananas comosus [L.] Merr.), Journal of Agricultural and Food Chemistry, 40: 599-603.
Table 1 Volatile compound in pomelo storage at ambient temperature (25 o C +3)
Volatile compounds RI % Relative peak area Odor description*
Day 1 Day 2 Day 3 Day 4
α-phellandrene 1210 0.58 0.46 0.37 0.21 citrus, green
α-limonene 1244 0.53 1.40 1.39 1.75 citrus, mint
α-terpinyl acetate 1248 1.86 0.59 0.45 0.00 herbal, citrus, spicy, woody, floral, waxy
β-terpinene 1254 0.11 0.64 3.19 3.80 refreshing
p-cymene 1322 0.70 0.55 0.57 0.37 solvent, citrus
3-methyl- 2-buten-1-ol 1378 0.00 0.25 0.22 0.38 fruity mango odor with apple, nuances
6-methyl -5-hepten-2-one 1390 0.00 0.00 0.20 0.56 fruity,citrus, musty, ketonic and creamy
3-methylpentanol 1412 0.54 0.78 1.01 1.10 roasty
3-hexen-1-ol 1444 0.64 0.84 0.81 1.04 green, grassy
1-octen-3-ol 1509 0.00 0.00 1.42 1.57 earthy, green, oily, vegetative and mushroom
acetic acid 1511 3.05 2.58 2.28 1.36 sour
heptanol 1516 0.00 0.00 1.42 1.72 musty, pungent, leafy green
δ-elemene 1523 4.39 3.89 3.43 3.00 wood
α-ylangene 1538 0.58 0.91 0.92 0.93 fruity
α-copaene 1547 0.80 1.26 1.56 1.66 woody, spice
2-ethyl-1-hexanol 1552 1.95 1.19 1.06 1.03 citrus, fresh, floral, oily, sweet
β-bourbonene 1574 0.44 0.75 1.09 1.24 herb
valencene 1633 1.68 1.55 0.91 1.11 green, oil
β-elemene 1649 1.88 1.82 1.57 1.39 wood
β-caryophyllene 1655 8.23 8.62 9.53 9.45 wood, spice
α-elemene 1698 1.61 1.35 1.33 1.22 wood
α-gurjunene 1725 3.15 3.13 2.55 2.26 wood, balsamic
α-humulene 1730 2.07 2.08 2.15 2.18 wood
isoledene 1736 3.00 2.94 2.87 2.58 -
α-amorphene 1751 5.44 5.37 5.48 4.74 wood
δ-selinene 1755 4.94 4.82 4.57 3.83 -
germacrene D 1771 0.17 1.96 2.24 2.54 wood, spice
aromadendrene 1781 5.43 5.30 5.09 4.47 wood
α-selinene 1787 4.31 4.23 4.14 3.60 pepper-like, orange
δ-cadinene 1823 15.08 15.91 15.95 15.15 thyme, medicine, wood
cyclopentyl-4-ethylbenzoate 1835 16.13 16.16 16.89 16.96 -
γ-selinene 1844 2.86 2.96 3.20 3.82 wood
α-muurolene 1858 2.14 2.02 1.97 1.82 wood
L-calamenene 1899 3.69 2.70 2.25 2.05 herb, spice
*odor description from flavornet
Table 2 Colour assessment and firmness of pomelo pulp during storage in ambient conditions.
Day
Ambient temperature (25 o C+3)
L* a* b* Chroma h Firmness (kgf)
1 65.194 a +2.49 0.939 a +0.306 17.969 a +0.654 17.995 a +0.659 87.009 a +0.947 0.813 a +0.17
2 64.831 a +2.76 0.742 a +0.33 18.186 a +1.77 18.21 a +1.77 87.413 a +1.29 0.804 a +0.24
3 67.147 a +1.53 0.669 a +0.12 17.924 a +1.78 17.964 a +0.80 87.878 a +0.40 0.794 a +0.25
4 67.381 a +1.33 0.58 a +0.28 17.765 a +0.75 17.776 a +0.75 88.349 a +0.89 0.745 b +0.11
a, b, c, … letters indicate significantly different (P