Effect of 1-Methylcyclopropene Released from 3-Chloro-2-methylpropene and Lithium Diisopropylamide on Quality of Harvested Mango Fruit
A simple way to generate active 1-methylcyclopropene (1-MCP) was developed by reaction of 3-Chloro-2-methylpropene (CMP) and Lithium Diisopropylamide (LDA) in the presence of water and the effects of the resultant 1-MCP gas on fruit quality, pericarp chlorophyll fluorescence and contents of ethanol and acetaldehyde in the pulp was investigated at a 3 day interval following subsequent storage for 12 days at 25°C. Retarded yellowing of fruit pericarp but increased disease incidence was observed in the CMP and LDA treated fruit. Furthermore, decrease in fruit firmness was delayed by 3 days in the CMP and LDA treated fruit. Compared to the untreated control, Titrable Acidity (TA) content in the pulp of CMP and LDA treated fruit decreased faster throughout the whole storage period while Total Soluble Solids (TSS) was lower within the first storage of 9 days, but higher in the later storage and TSS/TA ratio increased suddenly at the end of storage apparently higher optimal/maximal photochemical efficiency of photosystem II in the dark (Fv/Fm) and actual photochemical efficiency of photosystem II in the light (Yield = φPSII). Promoted ethanol and acetaldehyde production were observed during most of the storage time, while lower acetaldehyde level were tested by the end of the storage in the CMP and LDA treated fruit than the control fruit. These results indicated that application of combined CMP and LDA was a simple and feasible way and has great potential to delay ripening of Zihua mango.
to cite this article:
Ting Liu, Haiyan Zhang, Guoxiang Jiang, Fuwang Wu, Zhengjiang Qian, Hongxia Qu and Yueming Jiang, 2010. Effect of 1-Methylcyclopropene Released from 3-Chloro-2-methylpropene and Lithium Diisopropylamide on Quality of Harvested Mango Fruit. Asian Journal of Agricultural Research, 4: 212-219.
Received: January 20, 2010;
Accepted: April 06, 2010;
Published: June 24, 2010
Mango (Mangifera indica L.) fruit is famous for its attractive appearance,
pleasant flavour and rich nutrition. As a climacteric fruit grown in the tropical
and subtropical areas, mango fruit is highly perishable. Green, physiologically
mature mango fruit after harvest ripe within 6-7 days and then become overripe
and decay within 15 days at 25°C. In recent years, physical, chemical and
biological measures have been developed to extend storage life of mango fruit,
while commercial application of these technologies is restricted due to complex
or time-consuming operation, high cost or the safety in regard to human health
and environment as well as limited validity (Tharanathan
et al., 2006).
Gaseous 1-methylcyclopropene (1-MCP) is an efficient inhibitor of ethylene
action through binding to ethylene receptors with an affinity approximately
10 times greater than ethylene (Blankenship and Dole, 2003).
1-MCP can inhibit ripening of most postharvest crops at nL L-1 levels.
This chemically nontoxic substance is environmental friendly and harmless to
the public health. In 1999, commercial products of 1-MCP (EthylBloc for ornamental
crops and SmartFresh for edible crops) were certificated in America and approved
for food use by the Environmental Protection Agency (EPA) in 2002. Thus, 1-MCP
is widely investigated in climacteric and non-climacteric fruit, vegetables
and flowers (Chutichudet et al., 2010; Ramin, 2008;
The 1-MCP treatment maintained fruit firmness, inhibited activities of antioxidant
enzymes (Singh and Dwivedi, 2008; Wang
et al., 2009), delay the express of pectate lyases which degrade
pectins (Chourasia et al., 2006), thus increased
the number of days to ripening. 1-MCP could delay ripening of harvested mango
fruit (Hofman et al., 2001) while the effective
concentration was quite variable, which could be 0.1 μL L-1
in thin-pericarp cultivars such as Guifei (Wang et al.,
2006) or 200 μL L-1 in thick-pericarp ones such as Zihua
(Jiang and Joyce, 2000). Furthermore, the desirable
effect of 1-MCP treatment depend largely on the characteristics of the crops,
temperature, treatment duration, fruit maturity, time from harvest to treatment
and application times, which should all been taken into consideration (Blankenship
and Dole, 2003; Watkins, 2006).
Commercial application of 1-MCP to horticultural products is based on release
of gaseous 1-MCP from a 1-MCP/α-cyclodextrin complex after addition of
water or base solution in closed environments to ensure exposure of the crops
to the chemical for several hours. Hotchkiss et al.
(2007) reported the usage of 1-MCP in combination with modified atmospheres
(MA) by release of 1-MCP from a packaging film matrix. Direct production of
gaseous 1-MCP can meet well a commercial scale to control fruit ripening. Considering
the unavailability and/or relative high cost of commercial 1-MCP, a simple way
to generate the active 1-MCP referring to the method of Magid
et al. (1971) was developed in the present study. Two chemicals 3-chloro-2-methylpropene
(CMP) and Lithium Diisopropylamide (LDA) were combined and then reacted with
H2O resulting from fruit respiration, prior to the active 1-MCP was
released. The effect of the combined treatment of CMP and LDA on fruit ripening
and quality of mango was investigated.
MATERIALS AND METHODS
Mature green Zihua mango fruit were harvested from an orchard located in Guangzhou
Fruit Research Institute in August, 2008. Totally 150 kg of mango fruit were
selected for uniformity of size, color and freedom from defects. After dipped
for 10 sec in 1% sodium hypochlorite solution, the fruit were air dried and
randomly divided into two groups (150 fruit per group). One group was put into
glass jars (19 cm in diameter, 26 cm in height and 7.2 L in capacity; 15 fruit
jar-1) each with a small beaker at the bottom. A volume of 0.1 mL
3-chloro-2-methylpropene (CMP) (Aldrich, Inc. USA) + 0.3 mL lithium diisopropylamide
mono (tetrahydrofuran) complex solution (LDA) (Aldrich, Inc. USA) were injected
into the beakers before the jars were sealed. The concentration of the active
1-MCP produced by CMP and LDA was tested as the method below. The control fruit
were also sealed into jars for the duration of the corresponding CMP and LDA
treatments. The sealed jars were kept for 12 h at 25°C, then five fruit
were packaged in a low density polyethylene bag (0.015 mm thick). All the fruit
was stored at ambient temperature (25°C) for 12 days. 15 fruit was taken
at each sample time for the following evaluations and analyses. The experiment
was repeated twice and similar results were obtained.
Determination of the Active 1-MCP Concentration Generated by CMP and LAD
The active concentration of 1-MCP generated by CMP and LAD was measured
7 h after CMP and LAD was injected and the jar was sealed. A Gas Chromatography
(GC) machine (GC-2010, Shimazu, Japan) equipped with a capillary column (HP-PLOTQ
30 mmx0.32 mmx20 μm) and a Flame Ionization Detector (FID) was used. A
headspace gas of 1 mL drawn by a gas-tight syringe was injected into GC. Temperature
of the injection port and detector were 220 and 230°C, respectively. Temperature
program of the column oven was as follows: 120°C, 3°C min-1
to 150°C and then 10°C min-1 to 200°C. Iso-butylene was
used as the standard gas to calculate 1-MCP concentrations as reported by Jiang
and Joyce (2000). The tested concentration of 1-MCP generated by 0.1mL CMP
+ 0.3 mL LAD mL LDA were 138 μL L-1.
Evaluation of Peel Color and Disease Incidence
Peel color of individual fruit was estimated by measuring the extent of
the total yellow area on each fruit pericarp on the following scale: 0, green;
1, ≤1/3 yellow; 2, 1/3-2/3 yellow and 3, ≥2/3 yellow. The color index
was calculated using the formula:
Disease development was recorded as the proportion (%) of fruit surface with anthracnose or rot spot as follows: 0, no lesion; 1, ≤1/8 lesion; 2, 1/8-1/4 lesion; 3, 1/4-1/2 lesion; and 4, ≥1/2 lesion. The disease index (%) was calculated by the formula:
Detection of Chlorophyll Fluorescence
Chlorophyll fluorescence measurements were carried out at 25°C with
a portable fluorometer (PAM2100, Heinz Walz GmbH, Germany). A fiber-optic adapter
(2010-A, Walz) was used to fix the distance between the fiber optic terminus
and the fruit exocarp. Measurements were taken in two opposite positions of
each fruit at the same location in the fruit surface and then averaged. The
maximal efficiency of PSII photochemistry, Fv/Fm=(FmFo)/Fm was determined
using the fast actinic test (Run 2-procedure on the fluorometer) with the measuring
beam set to a frequency of 600 Hz after the fruit was dark-adapted for 20 min,
whereas the measurement of actual quantum yields of photosystem II, Yield =φPSII
= (Fm-Ft)/Fm were performed with the measuring beam automatically
switching to 20 kHz during the saturating flash (20 sec).
Assessments of Titrable Acidity (TA), Total Soluble Solids (TSS) and Firmness
Pulp tissues were homogenized in a grinder and then filtered with 8 layer
gauze. The filtrate was collected for analyses of TSS and TA contents. TSS was
assayed using a hand-held refractometer (J1-3A, Guangdong Scientific Instruments)
while TA was determined by titration with 0.1 M NaOH up to pH 8.65. Results
were expressed in percentage. The TSS/TA ratio was also calculated. Fruit firmness
was measured by a fruit sclerometer (GY-1, Hangzhou Top Instruments). Fruit
were peeled and measurements were then taken near the stem and head in two opposite
sides of each fruit.
Determinations of Ethanol and Acetaldehyde Production
The above-mentioned GC with a Rtx-Wax column (30 mx0.25 mmx0.25 μm)
was used to determine ethanol and acetaldehyde production of fruit pulp. Fruit
juice was extracted and stored in plastic tubes containing 0.4 g NaCl mL-1
juice at -20°C. Frozen juice was thawed under ambient conditions and 15
mL aliquot was then transferred to a 50 mL conical flask and sealed with a soft
rubber stopper. Samples were incubated at 80°C for 10 min. A headspace gas
of 1 mL drawn by a gas-tight syringe was injected into GC. The injection port
and detector temperature were 210 and 220°C, respectively. The column oven
temperature program was 40°C (5 min), 10°C min-1 to 65°C
(8 min), 30°C min-1 to 210°C (10 min). Quantitative analyses
of ethanol and acetaldehyde were carried out by using standard aqueous solutions
and by making the corresponding standard curves under the same condition.
The experiment design was completely randomized. Data represented the means
of at least 3 replicates and analyzed by one way analysis of variance (ANOVA)
using SPSS version 16.0 (SPSS Inc., Chicago, IL, USA). Significant differences
between means were tested using Least Significance Difference (LSD) or Duncans
New Multiple Range Test (DMRT) procedure at the 5% level.
RESULTS AND DISCUSSION
Changes of Peel Color, Disease Index and Firmness
After 6 days of storage, fruit turned yellow while disease, mainly anthracnose
and stem end rot development increased rapidly (Table 1).
Obviously lower color index but higher disease index was observed in the CMP
and LDA treated fruit in this storage period. Considerably higher rots rate
by 1-MCP was also founded by Hofman et al. (2001).
The treatment delayed fruit softening by 3 days. However, a more rapid decrease
in firmness occurred after 6 days of storage in the CMP and LDA treated fruit
than the control fruit.
Changes of Chlorophyll Fluorescence
Chlorophyll fluorescence is an indirect indicator of the physiological status
of green tissues (Maxwell and Johnson, 2000). Chlorophyll
fluorescence measurement has the advantage of detecting cellular injury resulting
from senescence in advance of the development of visible symptoms (De
||Effect of combined CMP and LDA on changes in color, disease
incidence, firmness of Zihua mango fruit stored at 25°C
|Data within a column with different letters are significantly
different at the 5% level
||(A, B) Effect of the combined CMP and LDA on Fv/Fm and Yield
in mango fruit stored at 25°C. Each point represents the Mean±SE
of three replicates
Fv/Fm and Yield referring to potential and actual quantum yield of photosystem
II, respectively, were reported in assessing storability of fruit and vegetables
(Bron et al., 2004; Schofield
et al., 2005). Jacobi et al. (2001)
suggested a remarkable positive correlation between chlorophyll fluorescence
values and quality of harvested mango fruit. Markedly higher Fv/Fm and Yield
value in the CMP and LDA treated fruit than that in the control fruit was observed
(Fig. 1A, B), which suggested that the postharvest
ripening of mango fruit could be postponed by the treatment.
Changes of TSS, TA and TSS/TA Ratio
Total Soluble Solids (TSS) increased at the beginning of storage and the
highest TSS content was observed on the 6th day while the increase
from of TSS content was postponed significantly by the CMP and LDA treatment
(Fig. 2A), which was coincide with the result of Wang
et al. (2006) by 1-MCP treatment. Titrable Acidity (TA) dropped quickly
after harvest. The lower TA was obtained in the CMP and LDA treated fruit (Fig.
2B). TSS/TA ratio was stable in the first 3 days of storage and then increased
slowly in the control fruit but rose rapidly in the CMP and LDA treated fruit
(Fig. 2C). Increased loss of TA content in the CMP and LDA
treated fruit may be due to anaerobic respiration which consumed more acid substrates
compared with the control fruit. This assumption can be supported by enhanced
ethanol and acetaldehyde production (Fig. 3A, B).
Changes of Ethanol and Acetaldehyde (AA) Production
The presence of ethanol and acetaldehyde is an indicator of anaerobic respiration
(Echeverria, 1988). As shown in Fig. 3,
the two fermentative metabolites had the same change tendency. In the control
fruit, ethanol and acetaldehyde production went up slightly during the most
of storage time. In contrast, the two compounds increased sharply immediately
after treatment and reached a peak on the 9th day in the CMP and LDA treated
fruit and then dropped quickly. At the end of storage time, acetaldehyde product
was lower, but ethanol production was still higher in the CMP and LDA treated
fruit than in the control. An increase in ethanol was also found in banana fruit
after 1-MCP treatment (Golding et al., 1999).
While 1-MCP inhibited ethanol formation in apple (Fan and
Mattheis, 2001) and there was no reports about the effect of 1-MCP on ethanol
and acetaldehyde production in mango fruit. Subtropical fruit including mango
have been proposed to be among the most sensitive to anaerobiosis damage (Pesis,
2005), thus the higher rots rate in the treated fruit than in the control
fruit may be due to the accumulation of ethanol and acetaldehyde.
||Effect of the combined CMP and LDA on contents of Titrable
Acidity (TA), Total Soluble Solids (TSS) and TSS/TA ratio in mango fruit
stored at 25°C. Each point represents the Mean±SE of three replicates
||Effect of combined CMP and LDA on ethanol and acetaldehyde
production in mango fruit stored at 25°C. Each point represents the
Mean±SE of three replicates
Furthermore, ethanol and acetaldehyde contribute significantly to inhibit
ripening (Burdon et al., 1996). The delayed ripening
of harvested mango fruit was consistent with the enhanced production of the
two compounds in this study. These results suggested that they played important
role in regulation the ripening and senescence of harvested mango fruit.
Preparation of active 1-MCP by a simple reaction of CMP and LDA was proven to be successful. Yellowing and softening of mango fruit were retarded while TSS, TA content and TSS/TA ratio were lower before the 6 days of storage in the CMP and LDA treated fruit compared with the control fruit, suggesting a potential role of 1-MCP in delaying ripening of Zihua mango fruit in the early storage period at ambient temperature, which was supported by higher potential and actual quantum yield of photosystem II. In addition, higher rots rate was correlated with enhanced ethanol and acetaldehyde production in the treated fruits than in the control fruit. Therefore, to obtain an extend shelf life of mango fruit by the CMP and LDA treatment, measures should be taken carefully to consider the control of both yellowing and disease development.
Financial support from the 11th Five-Year Key Technologies R and D Program of China (Grant No. 2006BAD22B03) are greatly appreciated.
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