Maturation Physiology under Modified Atmosphere of ‘Prata’ Banana
Treated Postharvest with 1-Methylcyclopropene
S. de Melo Silva1, a, O. do C. de Oliveira Neto2, R.E. Alves3 and
E. de Oliveira Silva3
1
DCFS/CCA/UFPB, C.P 04, CEP 58.397-000 Areia-PB, Brazil
2
CFT/UFPB, 58.220-000, Bananeiras-PB, Brazil
3
Pesq. Dr. Embrapa Agroindústria Tropical, CP. 3711- CEP 60511-110 Fortaleza-CE,
Brazil
Keywords: color development, respiratory profile, 1-MCP
Abstract
The aim of this research was to evaluate the influence of 1methylcyclopropene (1-MCP) and modified atmosphere packaging on the
maturation of banana cultivar ‘Prata’ harvested in the maturation stage 1. Banana
hands were treated at room temperature with 0 and 60 ppb 1-MCP in sealed plastic
chambers of 0.19 m3, during 24 hours. Following the exposition to 1-MCP, a set of
three fruits were packed in polystyrene trays and packed using XtendTM film
(Stepac, L. A., Israel) for modified atmosphere generation and kept under ambient
(AA) and modified atmospheres (MA) at 15°C and 90±2% of Relative Humidity and
room temperature (23±2°C and 85±2% RH). At each evaluation period, three
replications (1 set of three fruit/rep) from each treatment were used. 1-MCP
application delayed the onset of respiratory peak, also maintained fruit gloss and
retarded the increase in the a* and b* values, which is a result of the also delayed
transition from the green to the yellow skin color. However, the development of the
skin yellow color was very irregular at 15°C storage. On the other hand, 1-MCP
treatment resulted in a more intense skin yellow color development for fruits kept at
room temperature.
INTRODUCTION
Ripening of climacteric fruits, such as banana, is initiated either by natural
evolution of endogenous ethylene or by commercial exogenous ethylene ripening
procedures (Golding et al., 1998). In contrast, increased storage life is closely related to
maintenance of low ethylene levels (Sisler and Serek, 1997). The gaseous compound, 1methylcyclopropene (1-MCP), has been reported to inhibit ethylene action, and therefore,
repining. 1-MCP brings about its action by competitive inhibition of ethylene receptors.
Thus, 1-MCP has potential for the commercial control of ripening and senescence of
harvested bananas.
Modified atmosphere by flexible films is a versatile technology that is applied to a
wide range of fruits and vegetables (Kays, 1997; Beaudry, 2004). Fruit quality and shelf
life are related to the rate of respiration of the fresh produce. In turn, the rate of
respiration is a result of the genetic nature of the produce, its maturity stage, temperature
and the influence of oxygen uptake, and ethylene and carbon dioxide production (Kader,
1986). A storage life similar to that of fruit kept under refrigeration can be achieved at
ambient temperature by packing fruits using modified atmosphere (MA), mainly when
combined with ethylene absorbents such as potassium permanganate (Scott et al., 1970).
However, the general benefits of using MA associated to ethylene scrubbers is limited
because since temperature increasing can adversely influence fruit quality and shelf life as
CO2 levels became too high and/or O2 levels became too low, leading to anaerobic
respiration (Kays, 1997). The ethylene catalyzed rise in respiration that may increase this
problem should be inhibited by 1-MCP.
The objective of this work was to evaluate the influence of the treatment with 1a
[email protected]
Proc. IIIrd IS on Trop. and Subtrop. Fruits
Eds.: M. Souza and R. Drew
Acta Hort. 864, ISHS 2010
371
MCP in combination with modified atmosphere by X-tend® film on the physiology and
extension of the postharvest life of Prata banana stored at room temperature and 15°C.
MATERIAL AND METHODS
Bananas (Musa ssp.) cultivar ‘Prata’ were harvested during the commercial
harvesting season from an orchard in Bananeiras, Paraíba State, Brazil, in the maturation
stages 1 (physiologically ripen fruit, but with totally green skin). Fruits were harvested,
no later than 8 AM, and Banana hands were treated in sealed plastic chambers of 0.19 m3
(90 x 60 cm), with 60 and 100 ppb.L-1 1-MCP during 24 h, at room temperature (24±1°C).
1-MCP was applied as a gas, according to Fan et al. (1999) procedures. Bananas from the
treatment control (without 1-MCP) were also sealed in chambers under similar
conditions. Upon removal from the chambers, fruits from each treatment were stored at
room temperature (24±1°C) and 80% RH during 16 days. Rate of carbon dioxide
production for each treatment was measured hourly in a flow-through system by
ventilating approximately 1000 g of fruit enclosed in a 5-L glass jar with CO2-free air.
Each hour the system was closed and the CO2 produced was collected in 0.1 N KOH
solutions, which was afterwards tritrated with 0.1 N HCl solution. At each evaluation
period, four replications (1 set of three fruit/rep) from each treatment were evaluated. For
color changes evaluation, following the exposition to 1-MCP, a set of three fruits were
packed in polystyrene trays and packed using XtendTM film (Stepac, L.A., Israel) for
modified atmosphere generation and kept under ambient (AA) and modified atmospheres
(AM) at 15°C and 90±2% of Relative Humidity (RH) and room temperature (23±2°C and
85±2% RH). Objective skin color was measured with a portable Minolta Chromameter
CR-30, according to CIELAB system, which express color in three parameters: L*, that
corresponds to lightness; a*, that defines the transition from green (-a*) to red (+a*); and
b*, that represents the transition from blue (-b*) to yellow (+b*). The more distant from
the center (=0), the more saturated is the color (Calvo, 1989). Ripening of fruit was also
visually assessed by subjective skin color evaluation, which was measured by 10 judges,
using a 1 to 7 scale, with 1 = totally green, 2 = breaker; 3 = <25% color change; 4 = 25 to
50% color change; 5 = >50% but <100% color change; 6 = 100% color definition; and 7
= 100% color definition with light brown spots (over ripen).
A complete randomized design, with four replications (three fruits/rep), was used,
and arranged in a factorial scheme (2 x 6), with atmospheres evaluated, (AA, AM), 6
evaluation periods. MCP doses (0 and 60 ppb) and temperatures were evaluated
separated. Data were expressed as the average of four replications/treatment. Statistical
analyses, regressions and/or LSD, were performed using SAS procedures (SAS Inst., Inc.,
1988). Tukey’s multiple range test (P≤0.05) was used to discern between treatment
classifications when F values were significant for main effects. Unless stated otherwise,
only results significant at P≤0.05 are discussed.
RESULTS AND DISCUSSION
Control ‘Prata’ banana (without 1-MCP) ventilated with air began to ripen on day
8 and showed characteristic respiration climacteric pattern and normal yellow color
development. The maximum respiratory rate (climacteric peak), reached on day 11, was
98.7 mg CO2.kg-1.h-1. 1-MCP application delayed the onset and reduced the intensity of
the respiratory peak (Fig. 1). The initial rate of CO2 production of ‘Prata’ banana treated
with 1-MCP was lower than the control. These results clearly show the effect of 1-MCP
as an efficient inhibitor of ethylene action and suppressor of respiration, as also shown by
Golding et al. (1998) in bananas subgroup Cavendish, cultivar ‘Williams’. The rate of
CO2 production for fruits treated with 100 ppb was lower than those treated with 60 ppb
1-MCP. It is generally accepted that endogenous ethylene production has a continuing
role in integrating the many biochemical changes associated with ripening (Seymour,
1993). The results herein demonstrate that 1-MCP suppressed the rate of carbon dioxide
production and retarded the onset of the respiratory peak (Fig. 1). Therefore, it can be that
1-MCP blocked the normal adjustment of response of ethylene production in ‘Prata’
372
Banana. It may be that, since 1-MCP was applied to fruit at the maturity stage 1, it
occupied the ethylene receptors irreversibly and blocked their normal responses, mainly
when maintained at 15°C. Molecular studies suggest that in tomato the number of binding
sites may increase during normal ripening, and the ethylene perception may be upregulated in response to ethylene production, in a similar way that ethylene biosynthesis
is subject to positive feedback regulation (Klee and Tieman, 1997). It is largely accepted
that 1-MCP suppresses ethylene perception by receptors, inhibiting ripening (Sisler and
Serek, 1997). This suggestion is supported in here, since timing of onset and rate carbon
dioxide production at climacteric peak was affected by 1-MCP treatment. In tomatoes, 1MCP prevents the accumulation of a number of mRNAs coding for the expression of
ACC synthase, ACC oxidase and the ethylene receptors involved in positive feedback
regulation of autocatalytic (System 2) ethylene production (Nakatsuma et al., 1998).
Golding et al. (1998) have suggested, for banana ‘Williams’ treated with 500 nl.L-1 1MCP, that when new ethylene receptors are synthesized or are capable of ethylene
reception after 1-MCP treatment, a continuous presence of propylene activates the
ethylene receptors. In this study, on the other hand, for Prata banana treated with 60 nl.L-1
1-MCP, ripening was unevenly resumed eventually; however, the reversibility of the
effect of 1-MCP by following ethylene treatment was not tested.
The b* values increased after 6 days storage, for treatment control (Fig. 2),
independent on temperature. Fruits maintained under modified atmosphere tended to
present constant b* values during storage, as a result of the maintenance of green color.
The a* values for fruits of treatment control changed from negative (-a*) to
positive (+a*) during storage (Fig. 3), characterized by green color disappearance and
synthesis of other pigments. Fruits treated with 1-MCP, on the other hand, tended to
present negative values until the end of storage period, indicating that the pathways for
chlorophyll degradation and carotenoids synthesis were affected by 1-MCP treatment, and
therefore, at least indirectly, in ‘Prata’ banana they are influenced by ethylene. For, 1MCP treated fruits, the a* value started to be positive following 14 days storage at room
temperature. Fruits kept at 15°C, a* value was positive (changed from green to yellow)
following 24 days storage.
Based on L* values (Fig. 4), banana non-treated with 1-MCP (control) lost fruit
gloss during storage, independent on temperature or atmosphere utilized. Fruits exposed
to 1-MCP maintained constant L* values during storage. These results suggest that that 1MCP was effective in keeping fruit gloss.
Golding et al. (1998) reported that in Cavendish bananas, the role of ethylene is of
a catalyze, accelerating and coordinating the processes related to pigment synthesis and
chlorophyll degradation. In ‘Prata’ banana, the skin color evolution, for treatment control
(without 1-MCP), progressively increased from green (Grade 1) to yellow with light
brown spots (Grade 7), during storage at 15 and 23°C, independent on atmosphere. On the
other hand, 1-MCP significantly delayed skin color evolution of ‘Prata’ banana during
storage. Similar results were also reported for ‘Cavendish’ Banana, treated with 1-MCP
(Golding et al., 1998; Jiang et al., 1999; Harris et al., 2000). This effect was much more
evident when 1-MCP treatment was associated with modified atmosphere packaging (Fig.
5). However, the development of the skin yellow color was very irregular, persisting the
green coloration, mainly in the extremities of 1-MCP treated fruit. This irregular skin
color development can occur as a function of the positional difference between the rates
of novo-synthesis of ethylene receptors present in the skin and in the pulp of banana,
which differ with respect to ethylene evolution and ethylene response (Oetaker and Yang,
1995). 1-MCP applied in association with modified atmosphere (MA) packaging was the
most efficient condition in delaying skin color evolution in ‘Prata’ banana (P>0.01). The
positive effect of MCP × MA in delaying yellow color development was much more
evident when fruits were maintained at 15°C.
Fruits exposed to 1-MCP presented stronger yellow pigmentation, as compared to
the control. This may be due to the synthesis of other pigments or due to a reduction of
the rate of degradation/oxidation of the already synthesized pigments (Gooding and Goad,
373
1970; Gross et al., 1976). It seems that although fruit treated with 1-MCP eventually
resumed color development, it was irregular. According to Golding et al. (1999) color
evolution may occur dependent or independent from ethylene action. The data herein,
however, indicate that, at least indirectly, ethylene is related to color development in
‘Prata’. Among other changes, ripening of banana is accompanied by a change in peel
color from green to yellow. It is generally accepted that continued production and action
of ethylene are required for integration of these biochemical events. Peel degreening is
influenced by ethylene produced by the pulp (Dominguez and Vendrell, 1993) and is
thought to be mediated by a multienzyme system in which chlorophyllase unmasks stable
carotenoids present in mature peel (Gross et al., 1976). In this work, 1-MCP delayed color
evolution (Fig. 5) and disrupted degreening. Peel color for the control treatment
progressively evoluted from green (grade 1) to yellow with small brown spots (grade 7)
for fruit kept at 15 and 24°C, independent on atmosphere of storage. Incomplete and
uneven yellowing of the peel was a feature of 1-MCP treated fruit. Although yellowing is
initiated by ethylene, completion of the process involves enzymes whose biosynthesis
may be irreversibly disrupted by 1-MCP. Sisler and Serek (1997) related that 1-MCP
binds irreversibly to ethylene receptors and suggests that plants eventually overcome
inhibition by making new receptors. When new ethylene receptors are synthesized or are
capable of ethylene reception after 1-MCP treatment, probable color evolution will occur.
Collectively, based on color changes, treatment with 1-MCP kept constant the l*
values, maintaining fruit gloss, and retarded the increase in the a* and b* values, which is
a result of the also delayed transition from the green to the yellow skin color. However,
the development of the skin yellow color was very irregular, mainly at 15°C storage. On
the other hand, 1-MCP treatment resulted in a more intense skin yellow color
development for fruits kept at room temperature.
In conclusion, this research has confirmed that respiratory profile and color
evolution changes associated with ripening of ‘Prata’ banana may be dependent on
functioning ethylene receptors. Although banana treated with 1-MCP eventually resumed
ripening, there was some disturbance to the biochemical changes associated with normal
ripening. These changes include uneven peel degreening, and reduction of respiration
rate, probably resulting from a disruption of the normal regulation of ethylene production.
ACKNOWLEDGEMENTS
Financial supports from the Conselho Nacional de Pesquisa (CNPq) from Brazil
and from Rohm Haas Company are greatly appreciated.
Literature Cited
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efficiency of 1-methylcyclopropene delay the ripening of bananas. Postharvest Biol.
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Jiang, Y., Joyce, D.C. and Macnish, A.J. 1999. Extension of the shelf life of banana fruit
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(eds.), Biochemistry of Fruit Ripening. Chapman and Hall, London.
Figures
100
Without 1-MCP
60 ppb 1-MCP
100 ppb 1-MCP
80
-1
-1
CO2 Production (mg.kg .h )
Prata Banana
60
40
20
0
0
5
10
15
20
25
30
35
Postharvest Period (Days)
Fig. 1. Production of CO2, at room temperature, of banana cultivar ‘Prata’, harvested in
the maturity stage 1 (physiologically developed fruit, but with skin totally green)
and treated with 1-MCP (0, 60, and 100 ppb) during 24 hours, at room temperature
(23±1ºC).
375
AA
AM
60
0 ppb
23º C
50
6 0 ppb
23º C
40
P ra t a
b* Index
30
y 1 A A = 3 5 ,0 6 9 - 0 , 0 7 8 7 x + 0 , 1 1 2 3 x ²
R 2 = 0 ,9 0
20
10
60
6 0 ppb
15º C
0 ppb
15º C
50
40
30
y 2 A M = 3 7 ,5 1 2 - 1 ,2 8 2 4 x + 0 ,2 0 9 6 x ²
R 2 = 0 ,8 2
20
10
0
4
8
12
16
20
24
28
32
0
4
8
12
16
20
24
28
32
D a y s o f S t o ra g e
Fig. 2. Changes in b* index of banana fruit, cultivar ‘Prata’, harvested in the maturity
stage 1 (physiologically developed fruit, but with skin totally green) and treated
with 1-MCP (0 and 60 ppb) during 24 h, kept at 15°C and 23°C, under ambient
(AA) and modified (AM) atmospheres.
a* Index
AA
20
16
12
8
4
0
-4
-8
-1 2
-1 6
20
16
12
8
4
0
-4 0
-8
-1 2
-1 6
AM
y 1 A A = - 2 1 ,7 9 7 + 6 ,1 5 4 9 x - 0 ,3 0 2 7 x ²
R 2 = 0 ,8 5
y 1 A A = - 1 0 ,5 0 4 - 1 ,6 4 0 4 x + 0 ,3 4 8 7 x ²
R 2 = 0 ,9 4
6 0 ppb
23º C
0 ppb
23º C
P ra t a
y 2 A M = - 1 9 ,7 6 2 + 3 ,9 3 6 9 x - 0 ,0 9 6 2 x ²
R 2 = 0 ,8 7
y 1 A A = - 2 1 ,8 9 + 8 ,3 3 3 9 x - 0 ,5 1 4 7 x ²
R 2 = 0 ,8 8
0 ppb
15º C
4
y 1 A A = - 6 ,8 2 9 2 - 2 ,6 7 7 1 x + 0 ,5 2 5 8 x ²
R 2 = 0 ,7 4
6 0 ppb
15º C
8
12
16
20
24
28
32
0
4
8
12
16
20
24
28
32
y 2 A M = - 1 9 ,4 5 1 + 6 ,1 0 0 7 x - 0 ,3 2 4 4 x ²
R 2 = 0 ,9 2
D a y s o f S t o ra g e
Fig. 3. Changes in a* index of banana fruit, cultivar ‘Prata’, harvested in the maturity
stage 1 (physiologically developed fruit, but with skin totally green) and treated
with 1-MCP (0 and 60 ppb) during 24 hours, kept at 15°C and 23°C, under
ambient (AA) and modified (AM) atmospheres.
376
AA
AM
70
60
50
0 ppb
23º C
l* Index
40
6 0 ppb
23º C
y 1 A A = 4 8 ,4 1 8 + 5 ,6 0 6 5 x - 0 ,6 3 8 2 x ²
R 2 = 0 ,8 1
30
20
70
60
50
0 ppb
15º C
40
6 0 ppb
15º C
30
20
0
4
8
12
16
20
24
28
0
32
4
8
12
16
20
24
28
32
D a ys o f S to ra g e
Fig. 4. Changes in L* index of banana fruit, cultivar ‘Prata’, harvested in the maturity
stage 1 (physiologically developed fruit, but with skin totally green) and treated
with 1-MCP (0 and 60 ppb) during 24 h, kept at 15°C and 23°C, under ambient
(AA) and modified (AM) atmospheres.
AA
AM
7
y 1 A A = 2 ,0 8 8 5 - 0 ,3 5 9 6 x + 0 ,0 7 7 4 x ²
R 2 = 0 ,9 3
6
0 ppb
23º C
Color Evolution Grade (1-7)
5
y 2 A M = 1 ,4 1 9 4 + 0 ,1 8 9 6 x - 0 ,0 0 6 2 x ²
R 2 = 0 ,9 1
4
3
2
P ra ta
6 0 ppb
23º C
y 1 A A = - 0 ,8 7 8 2 + 1 ,5 2 4 7 x - 0 ,0 7 1 7 x ²
R 2 = 0 ,9 3
y 2 A M = - 0 ,3 6 7 9 + 1 ,1 5 2 x - 0 ,0 4 0 1 x ²
R 2 = 0 ,9 5
1
7
0 ppb
15º C
6
y 1 A A = 1 ,6 8 3 3 - 0 ,0 6 5 2 x + 0 ,0 5 1 5 x ²
R 2 = 0 ,9 4
5
y 2 A M = 1 ,6 8 1 + 0 ,0 4 6 1 x + 0 ,0 1 4 7 x ²
R 2 = 0 ,9 2
y 1 A A = - 1 ,0 8 3 3 + 2 ,1 9 7 9 x - 0 ,1 4 5 5 x ²
R 2 = 0 ,9 5
4
3
6 0 ppb
15º C
y 2 A M = - 0 ,6 3 3 3 + 1 ,8 1 0 5 x - 0 ,1 1 2 9 x ²
R 2 = 0 ,9 6
2
1
0
4
8
12
16
20
24
28
32
0
4
8
12
16
20
24
28
32
D a ys o f S to ra g e
Fig. 5. Subjective color evolution grade (1 to 7) of banana fruit, cultivar ‘Prata’, harvested
in the maturity stage 1 (physiologically developed fruit, but with skin totally
green) and treated with 1-MCP (0 and 60 ppb) during 24 hours, kept at 15°C and
23°C, under ambient (AA) and modified (AM) atmospheres.
377