This research aimed to investigate the effect of packaging materials and storage time on volatile profiles of mulberry tea. The mulberry tea samples were packaged in linear lowdensity polyethylene laminated aluminum (AL) bag and polypropylene (PP) bag and stored at 30\ub11\ub0C for 18 months. The volatile profiles were monitored using a headspace solid phase microextraction/gas chromatography-mass spectrometry. The results showed that storage time had no significant impact on the key volatile compounds of the AL packaged samples. However, some volatiles associated with lipid oxidation like hexanal and 4-oxo-2-nonenal were observed to significantly (p&lt;0.05) increase in the PP packaged samples with storage time

A. RUENGDECH

S. BENEDETTI

S. BURATTI

S. LIMBO

U. SIRIPATRAWAN

English

AIR Universita degli studi di Milano

SLIM 2019 
Shelf-life International Meeting 
Naples (IT), 17-20 June 2019 
Edited by 
G.G. Buonocore & E. Torrieri 
Special Issue 
CHIRIOTTI EDITORI 
?37 
 
 
 
 
 
 
EFFECT OF PACKAGING ON VOLATILE PROFILES 
OF MULBERRY TEA 
 
 
 
 
 
A. RUENGDECH1,2, U. SIRIPATRAWAN*1,2, S. LIMBO3, S. BENEDETTI3 
and S. BURATTI3 
1Department of Food technology, Faculty of Sciences, Chulalongkorn University, Phayathai Rd, 
Bangkok 10330, Thailand 
2The Novel Technology for Food Packaging & Control of Shelf Life Research Group, 
Chulalongkorn University, Phayathai Rd, Bangkok 10330, Thailand 
3Department of Food, Environmental and Nutritional Sciences (DeFENS), Università deli Studi di Milano, 
Via Celoria 2, 20133 Milano, Italy 
*Corresponding author: ubonratana.s@chula.ac.th 
 
 
 
 
 
ABSTRACT 
 
This research aimed to investigate the effect of packaging materials and storage time on 
volatile profiles of mulberry tea.  The mulberry tea samples were packaged in linear low-
density polyethylene laminated aluminum (AL) bag and polypropylene (PP) bag and 
stored at 30±1°C for 18 months. The volatile profiles were monitored using a headspace 
solid phase microextraction/gas chromatography-mass spectrometry. The results showed 
that storage time had no significant impact on the key volatile compounds of the AL 
packaged samples. However, some volatiles associated with lipid oxidation like hexanal 
and 4-oxo-2-nonenal were observed to significantly (p<0.05) increase in the PP packaged 
samples with storage time. 
 
 
 
 
 
 
 
Keywords: herbal tea, mulberry leaf, packaging, SPME-GC/MS, volatile compounds 
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1. INTRODUCTION 
 
The consumption of mulberry (Morus alba L.) leaf tea products is popularly increasing 
worldwide especially in Asian countries increasing due to its special flavors and health 
benefits (SÁNCHEZ-SALCEDO et al., 2015; SHOAIB ZAFAR et al., 2013).   
It has been recognized that the sensory quality of herbal tea especially flavor profile is a 
key factor for quality classification and content. Since the changes in flavor and aroma 
profile of herbal tea during storage result in the greatly decline in its quality and consumer 
acceptance, appropriate packaging is crucial for preserving the product's flavors and 
nutritional quality throughout the storage. HARNNURAK and RIEBROY (2014) reported 
that the alumimium foil bag could protect the quality attributes of mulberry leaf tea 
during storage better than paper bag and sachet, respectively. LEE and CHAMBERS (2010) 
reported that packaging materials significantly (p<0.05) affected changes in volatile 
components of green tea during storage.   
To date, several researches have undertaken on the quality attributes and health benefit of 
mulberry tea. However, scientific information on aroma constituents and quality attributes 
of herbal tea from mulberry leaves during storage are still limited. Information on the 
volatile compounds of mulberry tea is beneficial to the herbal tea industry for quality 
control of products and shelf life evaluation. The purpose of this study was to determine 
the effect of packaging and storage time on volatile profiles of mulberry leaf tea using 
headspace solid phase microextraction-gas chromatography/mass spectrometry (SPME-
GC/MS). 
 
 
2. MATERIAL AND METHODS  
 
2.1. Tea preparation and storage condition 
 
Herbal mulberry tea (Thai Silk Products Co., Ltd., Thailand) was prepared using the 
process of The Queen Sirikit Department of Sericulture as described by RUENGDECH and 
SIRIPATRAWAN (2019). One hundred grams of mulberry tea were packed into linear 
low-density polyethylene laminated aluminium (AL) bag (10×15 cm2; 0.0924 mm in 
thickness) and polypropylene (PP) bag (10×15 cm2; 0.0774 mm in thickness), sealed under 
atmospheric condition, and stored at 30±1°C in a controlled humidity chamber at 75% RH. 
The samples were randomly retrieved at three-month interval to monitor volatile profiles 
using SPME-GC/MS.    
 
2.2. Determination of volatile compounds  
 
The tea infusion was prepared by adding 2 g of mulberry leaf tea in 100 ml of hot water at 
95±2°C.  The samples were infused for 5 min and were then filtered through a Whatman 
No.4 filter papers.  
Volatile compounds of mulberry tea infusion were collected by SPME technique. Briefly, 
10 ml of tea infusion were pipetted into a 20 ml glass vial (Chromselection, Brescia, Italy) 
and 3 g of sodium chloride was added. The vial was then tightly closed with aluminum 
crimp cap attached with a PTFE silicone septum (Chromselection, Brescia, Italy). After 10 
min of sample equilibration at 40°C in an auto-incubator, the 50/30 μm 
Divinylbenzene/Carboxen/ Polydimethylsiloxane (DVB/CAR/PDMS) SPME fiber 
(Stableflex; Supelco. Inc., Bellefonte, PA, USA) was exposed to the headspace of the 
sample vial for 30 min and then immediately inserted into the gas chromatograph (GC) 
?39 
(AutoSystem XL GC, PerkinElmer, Waltham, MA, USA) injection port with splitless mode 
at 250°C for 5 min.  
The GC column was Stabilwax®-MS capillary column (30 m × 0.25 mm ID, 0.25 μm film 
thickness; Restek, Bellefonte, PA, USA) was employed for GC-MS analysis. Helium was 
used as carrier gas with flow rate at 1 ml/min. The GC oven temperature gradient was 
50°C (held for 5 min) initially, increased to 125°C (held for 3 min) at 3°C min−1, then 
ramped to 180°C (held for 3 min) at 2°C min−1, and finally increased to 230°C (held for 5 
min) at 6°C min−1. The transfer line temperature was 280°C. Mass spectrometer (MS) 
(Turbomass MS, PerkinElmer, Waltham, MA, USA) was coupled to GC. The ion source 
temperature was 230°C and the MS was scanned at 70 eV over 40 to 500 mass range. 
Compounds were tentatively identified by using the National Institute of Standards and 
Technology (NIST) database with the reverse match factor more than 800.  
Principal components analysis (PCA) was carried out to analyzed volatile compound data. 
PCA has been used to visualize the hidden trends in a data matrix composed of n (13) 
samples defined by m (12) selected volatile compounds, which changed in intensity 
during storage.  
 
 
3. RESULTS AND DISCUSSION 
 
The effects of packaging materials and storage time on volatile components of mulberry 
leaf tea stored at 30±1°C were determined using SPME-GC/MS. GC chromatograms of 
volatile profiles of mulberry leaf tea in PP stored for 0, 6, 12, and 18 months are shown in 
Fig. 1. Volatile compounds were then identified by comparison of their mass spectra of 
authentic reference compound with those of the NIST (version 11.0) database. Fifty-three 
volatile components in mulberry leaf tea include aldehyde, alcohol, acid, ester, and others. 
Volatile compounds including benzaldehyde; 1-octen-3-ol; 6-methyl-5-hepten-2-one; (E, 
E)-2,4-heptadienal; nonanal; decanal; 2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde; and 
6,10-dimethyl-5,9-undecadien-2-one found in our sample were also found in mulberry tea 
produced in China as report by LIU et al. (2012).  Hexanal and 2-hexenal, which have been 
reported to be responsible for green and grassy odors in mulberry leaves (RUENGDECH 
and SIRIPATRAWAN, 2019; TANAKA et al., 2009), also present in the mulberry leaf tea in 
our study. 2(4H)-benzofuranone,5,6,7,7a-tetrahydro-4,4,7a-trimethyl contributed to sweet, 
herbaceous, and tea-like odor has been reported as an important aroma constituent of tea 
and herbal tea (CHEN et al., 2013).  
The GC results showed that storage time did not affect volatile components of mulberry 
the leaf tea. The average concentration of all volatile components of the samples in AL did 
not significantly change over the whole storage period. However, intensity of volatiles of 
the PP packaged samples including 2-methyl-butanal; hexanal; 5-hepten-2-one,6-methyl; 
6-methyl-3,5-heptadiene-2-one; 3,5-octadien-2-one; heptan-2-one; 3,4-dimethyl- 
benzaldehyde; 4-oxo-2-nonenal; 3-buten-2-one-4(2,6,6-trimethyl-1-cyclohexen-1-yl); 2(4H)-
benzofuranone,5,6,7, 7a-tetrahydro-4,4,7a-trimethyl; 5,9-undecadien-2-one,6,10-dimethyl; 
and 1,6-octadien-3-ol- 3,7-dimethyl,2-aminobenzoate changed with storage time. The 
intensities of 2-methyl-butanal and 3,4-dimethyl-benzaldehyde found in mulberry leaf tea 
in PP bag gradually decreased with increasing storage time, whereas the remaining 10 
compounds gradually increased during 12 months of storage and rapidly increased from 
15 to 18 months of storage (Fig. 2). 
 
?40 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1. GC chromatograms of volatile compounds of mulberry leaf tea in PP bag during storage at 30±1°C, 
75% RH for 0, 6, 12, and 18 months. The peaks of twelve volatile compounds with color circle indicate 
significant (p<0.05) changed in intensity during storage. 
 
 
 
 
Figure 2. Changing in intensity of twelve volatile compounds found in the mulberry leaf tea packaged in PP 
during storage at 30±1°C, 75% RH for 18 months. 
A: 2-methyl-butanal; B: hexanal; C: 5-hepten-2-one,6-methyl; D: 6-methyl-3,5-heptadiene-2-one; E: 3,5-
octadien-2-one; F: 3,4-dimethyl-benzaldehyde; G: 4-oxo-2-noenal; H: 3-buten-2-one-4(2,6,6-trimethyl-1-
cyclohexen-1-yl); I: 2(4H)-benzofuranone,5,6,7,7a-tetra- hydro-4,4,7a-trimethyl; J: heptan-2-one; K: 5,9-
undecadien-2-one,6,10-dimethyl ; L: 1,6-octadien-3-ol-3,7-dimethyl,2-aminobenzoate. 
 
 
Changes in the intensity of some volatiles associated with oxidation reaction of 
components in mulberry leaf tea. Hexanal generated from lipid oxidation contributes to 
off-flavors such as stale, cardboard, and fishy in foods. Hexanal content is directly related 
to the deterioration of food quality during storage (MAARSE, 2017). A 4-oxo-2-nonenal is 
a lipid peroxidation product derived from oxidized omega-6 polyunsaturated fatty acids 
such as arachidonic acid and linoleic acid. It has been widely used as a marker of lipid 
?41 
peroxidation (LEE and BLAIR, 2000). 2-methyl-Butanal, which is a branched-chain 
aldehyde, is generally perceived as malty or chocolate-like odor in food products.  A 
decrease of 2-methyl-butanal of mulberry leaf tea in PP during storage may be attribute to 
the conversion of branched-chain aldehyde compounds to alcohol or acid compounds via 
reduction or oxidation, respectively (SMIT et al., 2009).  
SHOAIB ZAFAR et al. (2013) reported that the fresh mulberry leaves contain fat in a range 
of 0.64 to 1.51 g/100 g dried sample. While in dried mulberry leaves, fat is in a range of 
2.09 to 4.93 g/100g dried sample. During storage, UV-light, oxygen, and moisture can all 
induce lipid oxidation causing off‐flavor development in mulberry leaf tea. Since AL has 
better UV-light, oxygen, and moisture barrier properties than PP, it can protect the 
product from lipid oxidation better than PP bag. This result is in agreement with the 
studied of KAACK and CHRISTENSEN (2008), who reported that AL bag had more 
efficiency to protect the quality of tea processed from flowers of black elder (Sambucus 
nigra L.) than plastic film.  
The PCA used to facilitate the data interpretation of various volatile compounds of 
mulberry tea during storage at different time points. For PCA, data were made up of 78 
samples from 13 groups and each group had 6 replicates.  Each sample was analyzed 
using 12 selected volatile compounds, which changed in intensity during storage. The 
selected volatile compounds of all samples were arranged in a matrix (78 samples×12 
volatiles variables). Fig. 3 shows PCA score plot and loading plot of mulberry leaf tea 
stored at 30±1°C for 18 months using the selected volatile profiles data set. The PCA 
results allowed for good discrimination among samples, with the PC1 and PC2 can 
explain 99% of the total variance. The results showed that initial sample and all samples in 
AL located on the negative region of PC1. The result indicated that volatile compounds of 
the sample in AL were not significantly different during storage.  The samples in PP could 
divide into 2 groups; one group is the samples store at 3 to 12 months and the other is the 
samples stored from 15 to 18 months.  The PCA results are in accordance with the GC/MS 
results, which showed that volatile profiles of mulberry leaf tea in AL were not 
significantly different throughout the storage. Whereas storage time affected volatile 
intensity of the sample in PP. Twelve volatiles found in mulberry leaf tea in PP of which 
their intensities gradually changed during 12 months of storage and greatly changed at 15 
and 18 months of storage. Thus, the samples could be classified into three groups 
according to their volatile patterns. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 3. PCA score plot (a) and loading plot (b) on PC1 and PC2 of mulberry leaf tea in AL and PP bags and 
stored at 30±1°C, 75% RH for 18 months using twelve selected volatile compounds data set. 
 
 
?42 
The loading plot established the relative importance of each selected volatile compounds, 
and the relationships between the volatiles and the samples. Most of the selected volatile 
compounds positively correlated to PC1 whereas 2-methyl-butanal and 3,4-dimethyl-
benzaldehyde negatively correlated to PC1. From the loading plot, volatiles positively 
correlated to PC1 were associated with the samples in PP whereas volatiles negatively 
correlated to PC1 were associated with the samples in AL. The analysis of volatile profiles 
of mulberry tea suggested that packaging materials used affected its volatile profiles and 
possibly the odor and flavor of the products. 
 
 
4. CONCLUSIONS 
 
The results of this study demonstrated that packaging material and storage time affected 
volatile profiles of mulberry tea. AL bag showed high-effective barrier properties with the 
quality mulberry leaf tea were not significantly different throughout the storage. Due to a 
low effective barrier property of PP, the qualities of mulberry leaf tea significantly (p<0.05) 
difference during storage. To protect the product qualities during storage, AL bag is 
suggested as the packaging of mulberry leaf tea. The information obtained from this study 
is useful for the selection of suitable packaging material and storage time for mulberry or 
herbal tea.  
 
 
ACKNOWLEDGEMENTS 
 
The research was financially supported by the Thailand Research Fund (TRF) (The Royal Golden Jubilee 
Ph.D. Programme) and Chulalongkorn University [Grant number PHD/0175/2554 Code 
2.F.CU/54/B.1.O.JF, 2012]; and Overseas Academic Presentation Scholarship for Graduate Students, 
Chulalongkorn University. 
 
 
 
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Effect of packaging on volatile profiles of mulberry tea

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Effect of packaging on volatile profiles of mulberry tea

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