Modified atmosphere packaging reduces pericarp browning and maintains the quality of "Huong Chi" longan fruit (Dimocarpus longan) pretreated with citric acid

treatment, and the 
LDPE, PP, and LifeSpan L201 packaging, after 
28 days of storage. There were no significant 
differences in vitamin C content observed among 
the treatments until day 21 of storage. However, 
on the 28th day of storage, the vitamin C content 
in the non-packaged longan fruit and the fruit 
packaged with PP bags were remarkably lower 
than that in the longan fruit packaged with 
LifeSpan 201 (P< 0.05). In addition, the LDPE 
bag maintained a noticeably higher vitamin C 
level in the longan fruit than the PP bag, which 
had a level that was comparable to the control. 
Rate of fruit decay 
There was no observed fruit decay after 7 
days of storage (Figure 6). However, the fruit 
decay percentage increased markedly after 14 
days of storage in all the treatments. After 28 
days of storage, the recorded percentage of fruit 
Figure 4. TSS content (A) and TA content (B) of non-packaged longan fruit and longan fruit packaged in LDPE, PP, and LifeSpan 
bags. Vertical bars represent mean ± standard error. 
Figure 5. Vitamin C in non-packaged longan fruit and longan fruit packaged in LDPE, PP, and LifeSpan bags. Vertical bars 
represent mean ± standard error. 
A B 
Modified atmosphere packaging reduces pericarp browning and maintains the quality of ‘Huong Chi’ longan fruit 
860 Vietnam Journal of Agricultural Sciences 
Figure 6. Rate of decay of non-packaged longan fruit and longan fruit packaged in LDPE, PP, and LifeSpan bags. Vertical bars 
represent mean ± standard error. 
decay in the control was 11.12% (19.46 arcsin 
square root of fruit decay percentage), while the 
percentages were 7.16% and 4.86% (15.50 and 
12.67 arcsin square root of fruit decay percentage) in 
the LDPE and LifeSpan packaging treatments, 
respectively. The LDPE and LifeSpan modified 
atmosphere packaging significantly reduced the 
decay of the longan fruit. However, the PP 
packaging film did not show a significant effect 
on this attribute during storage (P< 0.05). 
Discussion 
The concentration of gases, especially O2, 
CO2, and C2H4, in the storage atmosphere is one 
of the major factors that affects the quality and 
postharvest life of fresh fruits and vegetables. A 
modified atmosphere containing a low level of 
O2 or high concentration of CO2 can retard fruit 
ripening, delay senescence, and maintain the 
quality of fresh produce (Kader et al., 1989). In 
our study, the LifeSpan and LDPE packaging 
films created equilibrium modified atmospheres 
(EMA) after 1 week and 2 weeks, respectively, 
while the PP packaging film could not create an 
EMA. Wang & Sugar (2013) also showed that 
commercial LifeSpan MAP bags could generate 
an equilibrium atmosphere of 12.3% O2 + 5.6% 
CO2 after 2 weeks of ‘Bartlett’ pears storage. In 
addition, a PE bag with a thickness of 80 µm used 
for longan storage developed the equilibrium 
atmosphere of 4% O2 + 9% CO2 (Khan et al., 
2016). Furthermore, previous studies reported 
that gas equilibrium could be created by 
perforation-mediated MAP. Hussein et al. (2015) 
found that PE film with 3, 6, or 9 perforations, 
0.8mm in diameter, reduced the O2 concentration 
to 17.6kPa, 18.6kPa, and 18.4kPa, 
respectively, within packages of pomegranate 
aril. The CO2 concentration within the packages 
also increased. LDPE film packaging (22.0 × 
30.0cm) with 8 perforations 0.5mm in diameter 
used for tomato storage also created an EMA 
with a lower O2 and higher CO2 concentration 
compared to the air (Li et al., 2010). In the 
present study, LDPE bags with perforations of 
0.01% of the surface area resulted in a higher 
level of O2 and a lower level of CO2 inside the 
packages. The gas composition obtained by the 
LifeSpan and LDPE provided substantial 
benefits to the longan fruit. 
Although all the packaging films maintained 
the L-value and delayed the pericarp browning of 
the longan fruit, the LifeSpan and LDPE films 
showed the strongest effects at the later stages of 
storage. The browning reaction has been shown 
to be accelerated by polyphenol oxidase (PPO) 
and peroxidase (POD), which are two enzymes 
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Nguyen Thi Bich Thuy & Nguyen Thi Hanh (2020) 
https://vjas.vnua.edu.vn/ 861 
that convert phenolic compounds to o-quinones, 
and phenylalanine ammonia lyase (PAL), which 
catalyzes the biosynthesis of phenolic 
compounds (Nguyen et al., 2004; Khan et al., 
2016). In agreement with our study, a modified 
atmosphere with 12% oxygen and 4% CO2 
inhibited PPO and PAL activities resulting in less 
peel browning in banana (Nguyen et al., 2004). 
The modified atmosphere of 17% O2 and 6% 
CO2 created by perforated PP packaging was also 
reported to reduce pericarp browning in litchi 
(Sivakumar & Korsten, 2006). The results in our 
study suggested that the effects of the LifeSpan 
and LDPE films on reducing pericarp browning 
in longan fruit may involve the inhibition of 
enzyme activities. Moreover, pericarp browning 
in longan fruit has also been shown to be 
associated with desiccation (Jiang et al., 2002), 
which rapidly occurs after harvest. In the present 
study, all the packages significantly reduced the 
desiccation of the longan fruit, which was 
reflected in weight loss reduction. Hence, the 
pericarp browning of packaged fruits was 
inhibited as a consequence. In addition, it was 
observed that the L-value was maintained in the 
non-packaged fruit during the first 2 weeks of 
storage, which may support the effects of the 
citric acid treatment as an anti-browning agent. 
Even though, longan fruit is a non-
climacteric fruit, the TSS and TA were shown to 
decrease gradually after harvest, even in cold 
storage conditions (Jiang et al., 2002). All 
packaging films in our study reduced the loss of 
the TSS in longan fruit, but the LDPE and 
LifeSpan films showed higher effects than the PP 
after 28 days of storage. The effect of the MAP 
on the TSS was probably due to the low 
concentration of O2 and high level of CO2 
atmosphere which reduced respiratory 
metabolism, resulting in decreased consumption 
of the TSS as substrates. At the end of storage, 
the loss of the TSS content in the longan fruit 
packaged in PP bags was more rapid. This could 
have been caused by anaerobic respiration 
occurring inside the PP bags due to undesirable 
atmosphere conditions with too low O2 and high 
CO2 concentrations. In agreement with our 
results, Khan et al. (2016) found that PE films 
maintained the TSS and TA contents in longan 
fruits, while the PP film led to a higher reduction 
of the TSS and TA. On the other hand, the MAP 
created by the LDPE and LifeSpan L201 films 
provided a preserving effect on vitamin C content 
in longan fruit, which was not obtained by the PP 
film. The present study agrees with Wang & 
Sugar (2013), who reported that commercial 
LifeSpan L254 suppressed the loss of ascorbic 
acid during storage via reducing membrane 
leakage. Modified atmosphere packaging and a 
controlled atmosphere were determined to 
decrease oxidative stress through the retention of 
ascorbic acid in fruits and vegetables (Hodges et 
al., 2004). 
The optimum gas composition in the storage 
atmosphere can suppress fungal decay of fruit, 
but the undesired modified atmosphere created 
by PP packaging film may cause physiological 
disorders, which could be followed by disease 
symptoms (Khan et al., 2016). In our study, the 
PP packaging film could not decrease the fruit 
decay compared to the control, which is the 
extent of the above discussion. Meanwhile, the 
LDPE and LifeSpan films strongly reduced the 
decay of the longan fruit after 4 weeks of storage. 
These results were in agreement with the studies 
on litchi and sweet cherry that reported that the 
appropriate MAP can reduce fruit decay, which 
was related to the inhibitory effect on the growth 
of disease pathogens (Sivakumar & Korsten, 
2006; Wang et al., 2015). 
Conclusions 
The LDPE and LifeSpan packaging films 
not only prevented the desiccation but also 
created the optimum EMA for the storage of 
longan fruit. This EMA significantly reduced 
pericarp browning, maintained the TSS content, 
reduced the loss of vitamin C, which contributes 
to the edible quality of fruit, and minimized fruit 
decay during cold storage. The PP packaging 
produced an undesired modified atmosphere for 
longan fruit, which resulted in severe decay 
symptoms and browning at the end of storage. 
Fruit stored in LifeSpan packaging films had the 
longest shelf life of 28 days, with a browning 
index less than 3, and a percentage of fruit decay 
Modified atmosphere packaging reduces pericarp browning and maintains the quality of ‘Huong Chi’ longan fruit 
862 Vietnam Journal of Agricultural Sciences 
less than 5%. This MAP extended the shelf life 
of the longan fruit more than 7 days longer than 
the control. 
Acknowledgments 
This study was funded by the “Development 
of innovative technologies on postharvest 
management for longan fruit fulfilling the 
requirement of domestic trading and exporting” 
project, No. 739/HD-BNN-KHCN, Ministry of 
Agriculture and Rural Development, Vietnam. 
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