American-Eurasian J. Agric. & Environ. Sci., 9 (3): 297-302, 2010
ISSN 1818-6769
© IDOSI Publications, 2010
Effect of Stage of Ripening on Mechanical Damage in Tomato Fruits
Salamolah Mohammadi-Aylar,
Shahzad Jamaati-e-Somarin and 1Jafar Azimi
1
2
Islamic Azad University, Ardabil Branch, Ardabil, Iran
Young Researchers Club, Islamic Azad University, Ardabil Branch, Ardabil, Iran
1
2
Abstract: Mechanical damage is the major cause of postharvest losses and among the perishable
crops tomato is susceptible to mechanical injury considrably. By conducting a series of impact tests
(from 0.18 to 2.88 J) by a pendulum impact apparatus, occurance of damage, in the form of rupture and
latent damage, were investigated as affected by stages of ripening (pink, ripening, maturity and
Plasmolism) and variety (Super Bta and Petoerly-ch). According to the results at any treatment of variety
and stage of ripeness, falling of tomatoes from maximum height of 59 cm does not occure any rupture in fruit,
causes injury in tomatos as degradation as a kind of latent damage. However, the minimum energy required for
rupture injury was about 1.58 J and 0.84 J in first and third stages of ripenening, respectively. According to the
results of ANOVA, there are no differences between two varieties based on rupture injury, whereas, impact
energy and especially stage of ripeness had significant effect on all types of mechanical damage in tomato fruit.
Also, the results showed that the severity and rate of latent damage increase progressively, through 24 to 72
hours of storage of fruits in natural conditions. Ripenenning stage is the major factor affect severity of latent
damage through 72 hours after impact.
Key words: Tomato
Impact
Latent damage
Ripeness
INTRODUCTION
Mechanical injury
loading, variety, texture, maturity, temperature, size,
shape, etc., [4]. In this case, McColloch [5] reported on
hidden and cumulative bruising injury on tomato due to
dead load and impact corresponding to maner in which
tomato are bruised during commercial handling. Van
linden, et al., [6] tried to present a method to evaluate
bruise damage in tomato and establish a method to
determine the bruise susceptibility of different tomato
cultivars by a statistical model. Allende, et al. [7]
characterized factors that determine puncture injury
during handling of tomatos. Also, Desmet, et al. [8]
accuired data on mechanical impacts using an
instrumented sphere to identify the critical points where
puncture injury may occur in handling chain in
postharvest operations of tomato. He also tried to predict
the puncture injury of a susceptible and not susceptible
cultivar under practical onditions. In addition, it was
mentioned that tomatoes at harvest were less
susceptible to puncture injury than after storage for
several days [8]. Geyer et al. [9] reported the
incidence of cracks and bursts after harvest and
Mechanical damage is the major cause of postharvest
losses in fruits and vegetables [1] specially in
undeveloped countries and considerable research efforts
are required in this relation. Mechanical damage occures
in the postharvest handling system primarily in two ways:
impact forces and compressive forces. Excessive impact
occure during harvesting, grading, handling and
transportation [2]. Among the perishable crops tomato
(Lycopersicon esculentum) is very susceptible to
mechanical injury. In a study of a tomato handling system
Campbell et al. [3] found that up to 40% of the crop
sustained mechanical damage.
Mechanical damage to tomato is manifested by watersoaked cellular breakdown of the cross-wall and cavity
[4]. However, despite extensive development in
mechanical harvesting and handling of tomato, research
on resistance of this product to mechanical damage has
been limited. The bruise susceptibility of fruits and
vegetables depend on many factors such as severity of
Corresponding Author: Shahzad Jamaati-e-Somarin, Young Researchers Club, Islamic Azad University,
Ardabil Branch, Ardabil, Iran, Tel: +989141594490, E-mail: [email protected].
297
Am-Euras. J. Agric. & Environ. Sci., 9 (3): 297-302, 2010
Van Zeebroeck et al. [10] investigated to verify the
hypothesis that within a cultivar higher absorbed
energy of tomato also indicates higher bruise damage
when impacted by the same impact energy.
However, bruises are not always immediately visible
but they become noticeable during subsequent handling
shelf life [6]. In this case a rilaible description is not
available. Another factor which affects tomato bruising is
the stage of ripening which considered in the researches
very seldom. Hense, it is useful to consider fruit
degradation after impact, which cause some type of
deterioration of fruit and is known as latent damage, in
addition to rupture injury, which cause the water loss of
fruit.
Therefore, the objectives of this study is: (i) to
identify critical ripeness stages where rupture may
occure; (ii) to determine the effect of stages of ripeness
on fruit degradations after impact; and (iii) to compare
two varieties of Super Beta and Petoerly-ch in relation to
mechanical damage.
(impact levels) cosidered in the experiments (Table 1)
according to classification of severity of impact handling
systems. In this classification two broad categories:
low energy system (less than 0.9 J) and High energy
system (about 1.5 J) are introduced [2].
An impact pendulum apparatus developed at the
university of Mohaghegh Ardabili, department of
agricultural machinery [11], with 150 cm lentgh of
pendulum wire, was used to apply controlled impact
energy to each fruit. The whole fruits of tomato were
sujected to impact after measuring the weight and 3
principal diameters of the samples.
Damage Susceptibility: To investigating damage
susceptibility, it is usual to develop a relatonship between
the impact energy and size of damage in the form of area
or volume of damage. This teqchnique was utulized by
Mohsenin [4]. But in tomato fruit, it is very hard to
detect the bruised area because of little or absulutly no
skin or flesh colour change. Accordingly, in adition to
considering direct rupture injury, immediately after each
test the samples were evaluated for any change on the
skin of tomatoes as a kind of fruit deterioration. To obtain
an accurate evaluation the following bruise classes were
defined which could show damage severity (Table 2).
To evaluate the latent damage it was necessary to
consider the deterioration of fruits during 72 hours after
impact. Therefore, at three stages (24, 48 and 72 hours
after the impact) the visual evaluations were done. During
this priod the storage condition was 18°C and 80%
relative humidity (natural environmental condition in
comercial handling in the region). All statistical analysis
was performed using the Mstat-C statistical software, in
the form of a randomized factorial experimental design.
MATERIALS AND METHODS
Sample Preparation and Impact Test: Two varieties of
tomato (Super Bta and Petoerly-ch) were examined in the
impact tests and for each cultivar, 160 tomatos were hand
picked directly from orchard in random and stored at 18°C
(as in real process in comercial procedure) for 16 days.
Four stages of tomato ripeness, means: pink, ripening,
maturity and plasmolism, mached to 1, 6, 11 and 16 days
after harvest, respectively, were considered in the tests.
For each treatment 10 replications were utilized.
At each ripeness stage the moisture content of
samples were measured. Also, two levels of height of drop
Table 1: Different impact levels and their mean values used in the experiments
Drop Height (mm)
Impact energy (J)
Level 1
1180
1.16 -1.71(1.4)
Level 2
590
0.29-0.50 (0.4)
Table 2: Class index for different types of deteriorartion after impact
Type of deterioration
Class Index
no bruis
I
little skin softness
II
medium skin softness
III
severe skin softness
IV
black area with little faded
V
completely faded
VI
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Am-Euras. J. Agric. & Environ. Sci., 9 (3): 297-302, 2010
RESULTS AND DISCUSSION
Table 3 sumerized the physical conditions of the
samples in the experiments. It could be seen that the
moisture content increase until 11 days after harvest and
then decreased in plasmolism stage. Indeed, it is a natural
phenomena in which unsoluble liquids such as Pectine
transform to simple compositions which caused the water
to freedom and increasing water amounts in fruit flesh.
Also, during 16 days after harvest in the environmental
condition of 14 to 18 degree of centigrade (Plasmolism),
tomato lose a fraction of its water.
According to obtained results, at any treatment of
variety and duration of time, falling of tomatoes from
maximum height of 59 cm does not occure any rupture in
fruits. Whereas, in falling of fruits from 118 cm height the
minimum rate of ruptures occurred in 30% of the samples
at first stage of ripness (Table 4). However, the minimum
energy required for rupture injury was about 1.58 and 0.84
J in first and third stages of ripening, respectively. Nearly
in all samples, rupture occurred at the bottom of the fruit
where the fruit joint to stalk (Fig.1). It seems that the
impact caused to develop the fllaws which exist at the
bottom of the fruit as like as the results of the
compression tests on similar varieties [10].
It was observed that the percentage of rupture was
increased proportional to development of ripening stage
(Table 4). Figure 2 shows that the rate of rupture does not
depend on rate of kinetic energy. Eqation (1) as a 3D
Fig. 1: Rupture and its location on bottom of fruit
statistical regression model, indicate that the percent of
rupture (Z) depend only to stage of ripeness (X)
(Figure 2):
z=a+bx2+cx3
(1)
Based on this result, it is prefered to use a 2D model
(Eq. 2). Indeed, a simple linear model define the
relationship between percent of rupture (Z) and stage of
ripeness (x) exactly (r2=0.89).
Z=29.8 + 4.95x
(2)
According to the results of analysis of varience,
there are no differences between two varieties based on
mechanical injury, whereas, impact level and stages of
Table 3: physical specifications of the samples in various treatments
Var.
Supper-Beta
Petoerly-ch
--------------------------
------------------------------------------------------------
----------------------------------------------------------------
Stages of Ripeness
MC (%)
MC (%)
Pink
74
143.2
75.2
Ripening
79
123.3
81
117.4
Maturity
90.5
134.1
93.4
115.6
Plasmolism
81
104.3
82
110.5
Weight (gr)
Weight (gr)
131.9
Table 4: Percentage of rupture injury in various treatments
Var.
Supper-Beta
Petoerly-ch
-------------------------
------------------------------------------------------------
---------------------------------------------------------------
Ruptured (%)
Ruptured (%)
Days after harvest
Time Stages
Pink
6
Ripening
11
Maturity
16
Plasmolism
Energy (mJ)
Energy(mJ)1
35
1.66
30
1.58
0
0.50
0
0.44
60
1.53
50
1.20
0
0.40
0
0.55
100
1.71
100
1.16
0
0.42
0
0.29
100
1.16
100
1.22
0
0.37
0
0.40
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Am-Euras. J. Agric. & Environ. Sci., 9 (3): 297-302, 2010
10
7.5
5
2.5
15
12.5
17.5
Maturity Stage
1.1
1.2
1.3 Energy
1.4
1.5
1.6
1.7
100
90
100
48
70
72
Rupture
80
80
60
60
50
0
40
30
0
I
II
0
0
0
III
IV
Severity of
Deterioration V
40 0
40
0
0
0
0
0
0
100
0
80
50
40
72
0
0
I
0
II
Severity of
Deterioration
III
0
0
IV
0
0
V
60
40
0
40
20
0
0
0
24
20
0
0
Samples (%)
50
0
72
48
Houers
Fig. 3: Quantity and severity of damage during 72 hours
after impact in Petoerly-ch variety and at first
stage of ripness (pink)
Ripening Stage
24
40
40
40
30
48
20
72
0
20
0
I
II
20
0
0
0
0
0
IV
0
Severity of
0
Deterioration V
48
24
III
0
50
45
40
35
30
25
20
15
10
5
0
Samples (%)
50
40
48
72
Houers
The results showed that at a constant level of impact
energy, which did not yield any form of skin rupture, the
factor of rippening level significantly affected severity
and quantity of damage. In other words, it is very
important to know the level of ripening stage, that impacts
occure after it. Indeed, when impact done on tomatoes in
pink stage, it did not reach to sixth class of damage (VI),
even after 72 hours storage in natural condition. In this
relation, figure 2 shows that only 20% of samples reached
to fifth class of damage (V ).
However, when tomato received impacts after second,
third and fourth stages of ripeness (means: ripening,
maturity and plasmolism) quantity and quality of damage
increase progressively. Altough, there is a considrable
difference between ripening stage and two later stages.
Indeed, if the fruit recieves impact after ripening stage
only 20% of samples yield the most severe damage, means
completely faded and 40% of samples yield to black area
and with little faded. While, if the impact occure on
tomatoes after third and fourth stages of ripeness, 100%
of samples involve fifth and sixth levels of deterioration
(Figures 3 to 6).
Accordingly, we can distinguish a critical condition
between second and third stage of ripeness (ripening and
maturity) of tomato in which latent damage increase in
quantity and severity (Fig. 7). These results were similar
in both varieties (Super Bta and Petoerly-ch).
It is important to notice that, in every two varieties
and in a constant level of kinetic energy (590 mJ), between
50 to 100% of damage occure in fruits, if the impact takes
place after 2nd, 3rd or 4 th stage of ripness and its severity
increases with the increase of ripness stages. While the
similar amount of kinetic energy did not make any form of
damage in fruits at least at 24 hours after impact.
100
48
0
Fig. 5: Quantity and severity of damage during 72 hours
after impact in Petoerly-ch variety and at third
stage of ripness (maturity)
Pink Stage
24
70
60
50
40
30
20
10
0
60
24
Fig. 2: Percentage of rupture increase proportional to
stage of ripeness (Time) (r2=0.90)
100
90
24
Samples (%)
Time
72
Houers
Fig. 4: Quantity and severity of damage during 72 hours
after impact in Petoerly-ch variety and at second
stage of ripness (ripening)
ripeness had significant effect on all types of mechanical
damage (ruprure and latent damage) on tomato fruits. The
same results obtained for interaction of impact level and
stage of ripeness.
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Am-Euras. J. Agric. & Environ. Sci., 9 (3): 297-302, 2010
Plasmolism Stage
1.5
100
100
100
90
80
70
60
50
40
30
20
10
0
24
0
I
0
II
0
0
0
III
0
0
0
0
0
0
IV
Severity of
Deterioration V
0
0
0
Samples (%)
48
72
0
0
24
Damage
100
StagesOfRipeness
40
20
Plasmolism
Maturity
Complete Faded
Little Faded
Sever Softnes
Medium Softnes
0
Little Softnes
500
450
400
350
300
250
200
150
100
50
0
20
30
40 Storage
50
60
70
As shown in Figures 2-5, the duration of storing
fruits in local natural condition (18°C and 80% relative
humidity) had a significant effect on quantity and severity
of latent damage in tomato fruits. This result was similar
in two varieties under this study. Consequently, it is
reasonable to propose for any suitable change in
environmental condition of tomatoes, sudenlly after
impact. This result could be seen in figure 8.
Equation (3) shows that the rate of damage (z) could
be modelled as a linear surface and based on this model
the time of storage (in natural condition) is the main
independent parameter (y), while the stage of ripeness (x)
has the minor effect (Figure 9).
60
No Bruise
4
Fig. 9: Percentage of increasing of rupture proportional to
stage of ripeness (Time) (r2=0.86)
80
Damage (%)
3.5
Houers
100
Ripening
Pink
z=a+bx+cy+dy2
1.
Damage
2.
3.
4.
Stora..
Ripening Maturity
Plasmolism
Stages of Ripeness
72
48
24
(3)
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Fig. 7: Quantity and severity of damage based on stage of
ripeness in Petoerly-ch variety
Pink
3
72
48
Fig. 6: Quantity and severity of damage during 72 hours
after impact in Petoerly-ch variety and at fourth
stage of ripness (plasmolism)
100
90
80
70
60
50
40
30
20
10
0
2
2.5
5.
Fig. 8: Effect of duration of time after impact on quantity
of damage in different stage of ripeness
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