Effects of Impact Levels and Storage Durations on Fuji Apple Bruising

Abstract

Fruit quality is adversely affected by bruise damage. Bruises occur under dynamic and static loading when stress exerted over the fruit exceeds the failure stress of the fruit tissue. The ability of fruits such as apples to resist bruising is a significant factor to be considered during the post-harvest handling and processing of the fruits. Therefore, studies should be performed for post-harvest preservation of the fruit quality parameters. In this study, the effects of storage durations and impact energy on bruise susceptibility of Fuji apples were investigated. Apple fruits were subjected to dynamic loading by means of a pendulum at different levels of impact energy: low (0.06 J), medium (0.11 J) and high energy (0.17 J). Three different impact locations (stem side, lateral side and blossom side) were marked over the apples by an impactor. The tests were carried out at 3 storage times (1 st , 3 rd and 6 th month). Bruise susceptibility was obtained by measuring the bruise volume after an impact test. It was demonstrated that increasing storage time and impact energy increased the bruise volumes of the Fuji apples. Moreover, the results revealed the maximum bruise sizes over stem sides and the minimum bruise sizes over lateral sides of the fruits.

Full text

190
Effects of Impact Levels and Storage Durations on Fuji Apple
Bruising
*Elcin YESILOGLU, Yesim Benal YURTLU
Ondokuz Mayis University, Faculty of Agriculture, Department of Agricultural Machinery,
55139 Samsun-TURKEY
elciny@omu.edu.tr
Abstract: Fruit quality is adversely affected by bruise damage. Bruises occur under dynamic and
static loading when stress exerted over the fruit exceeds the failure stress of the fruit tissue. The
ability of fruits such as apples to resist bruising is a significant factor to be considered during the
post-harvest handling and processing of the fruits. Therefore, studies should be performed for
post-harvest preservation of the fruit quality parameters. In this study, the effects of storage
durations and impact energy on bruise susceptibility of Fuji apples were investigated. Apple fruits
were subjected to dynamic loading by means of a pendulum at different levels of impact energy:
low (0.06 J), medium (0.11 J) and high energy (0.17 J). Three different impact locations (stem
side, lateral side and blossom side) were marked over the apples by an impactor. The tests were
carried out at 3 storage times (1
st
, 3
rd
and 6
th
month). Bruise susceptibility was obtained by
measuring the bruise volume after an impact test. It was demonstrated that increasing storage
time and impact energy increased the bruise volumes of the Fuji apples. Moreover, the results
revealed the maximum bruise sizes over stem sides and the minimum bruise sizes over lateral sides
of the fruits.
Key words: Apple, impact, bruise, location, storage
INTRODUCTION
Bruising is usually observed because of impact,
compaction and vibration like static and dynamic
external forces (Holt et al., 1981). Dynamic forces are
more effective in bruising of agricultural materials
during the transport, handling and processing of the
materials because occurrence frequency of dynamic
forces during these phases are higher than the
frequency of static forces (Van Zeebroek et al., 2007).
Fruits are exposed to dynamic external forces during
the pouring into boxes, conveyance over the packing
lines and packing (Nelson and Mohsenin, 1968).
These dynamic forces result in bruising over the fruit
surfaces. Color condensation is observed over bruised
locations of the fruits through the juice oxidation.
Since the biologic material is still alive, juice loss
speeds up in bruised fruits and respiration heat
increases. Such processes alter product quality
parameters in a short time (Eraltan, 2005).
Variations in mechanical characteristics of
agricultural products have significant impacts over
their bruise susceptibility. Temperature, humidity,
growth and ripening stage like physical and biological
factors may result in various changes in mechanical
properties. In most cases, temperature significantly
effects mechanical characteristics and bruise
susceptibility of agricultural products (Yurtlu, 2012).
Bruises over fruit surfaces result in significant
losses in fruit quality parameters. Apples are included
in fruit groups prone to bruises during the harvest and
post-harvest processes. Therefore, the factors
influencing bruises and their impact levels should be
determined to prevent or diminish the harvest and
post-harvest losses in apples.
Apples (
Malus communis
L.) have been grown in
Turkey for years and they are the most common
moderate climate fruit of the country. Although
Turkey has great cultivar diversity in apples, fruit
quality and post-harvest preservation are emphasized
for only a few of them (Ozupek, 2010).
World annual total apple production is 76 378 738
tons. With regard to producer countries, China has
the first place with 37 000 000 tons, the USA has the

191
second place with 4 110 046 tons and Turkey has the
third place with 2 889 000 tons. These top three
countries are respectively followed by Poland, India,
Italy, Iran, Chili, Russian Federation, and France
(Anonymous, 2012). Positive contributions of such
productions to country economies will be possible
through supplying them to consumers with the
minimum possible loss of quality and returning to the
producers with the maximum profit.
Schoorl and Holt (1977) investigated the effects of
storage durations and temperatures over the impact
bruises of Jonathan, Delicious, and Granny Smith
apples and observed decreasing bruise resistances
with increasing storage durations. Researchers
indicated significant impacts of storage duration on
bruise formation and increasing bruising with
increasing storage durations.
Niel et al., (1992) carried out impact tests over
four different peach cultivars (Prunus persica (L.)
Batsch) and investigated the relationships between
bruise resistance and the cultivars. Researchers used
different impact variables as of upper impact force,
contact time, energy absorbance, percent absorbed
energy, three different fruit ripening stages and three
different drop heights. Impact variables varied based
on the cultivars. Decay occurrence and volume
increased with the increasing drop-heights and
ripening levels.
Krzysztof et al., (2008) performed impact tests
over Melrose apples with different drop heights.
Researchers used 20, 35, 50, 70 and 80 mm drop
heights and observed increasing bruise resistance
coefficients with increasing drop heights. Researchers
observed the least bruise resistance at 20 mm drop
height. They also reported that the fruits stored at
20C for 4 weeks had lower bruise resistance than the
newly harvested apples.
Zarifnesfat et al., (2010) determined that bruise
volumes over Golden Delicious apples formed by a
pendulum impact apparatus. Researchers investigated
the relationships between radius of curvature,
temperature, acoustic firmness characteristics and
impact force-impact energy. They reported increasing
bruise damage with decreasing acoustic firmness,
increasing radius of curvature and temperature
values.
The present research was conducted to investigate
the bruise susceptibility of apples locations under
dynamic loads based on storage durations. Tests were
carried out to find out the effects of storage durations
and dynamic loads on bruise volumes.
MATERIALS and METHOD
The
Fuji
apples of the present research were
manually harvested during the commercial harvest
period of the year 2012 (October) from the orchards
of SAMMEY in Samsun. Apples were stored at 1C
temperature and 90% relative humidity for 30, 90 and
180 days. Before the measurements, apples were
kept 21±2C for an hour to reach the ambient
temperatures.
Impact tests were implemented with an impact
apparatus. There is a 0.545 m-long pendulum arm
over the apparatus. The steel impact head with a
radius of curvature of 25 mm was installed over the
pendulum arm. A force sensor was installed on impact
head (Dytran instruments 1051V3) (Van Zeebroeck et
al., 2003). The data signals from the force sensor
were gathered by (SCC-68 I/O) connector block and
(NI-PCI-6221) card and processed through C#
programming language.
The impact energy are obtained from the
calculated kinetic energy of the pendulum arm just
before and just after impact.
To apply the same energy, an initial angle of the
pendulum arm was fixed. Three different impact
locations (stem side, lateral side, and blossom side)
were placed in face to impactor. (Van Zeebroeck et
al., 2003)
Three different impact levels were used as
summarized in Table 1. Implemented impact energy
levels were selected to be above the critical impact
levels for apples (Zarifnesfat et al., 2010.)
Table 1. Overview of different nominal impact levels
applied on apples
Impact Energy (J) Impact Force (N)
Average SD

Average SD

Level 1
0.064
± 0.008
54.618
± 4.16
Level 2
0.116
± 0.018
74.818
± 9.66
Level 3
0.176
± 0.025
98.86
± 11.20
*
:
Standard deviation

192
The radius of curvature measurement device
presented in Figure 1 was used to measure the radius
of curvature of impact region. The radius of curvature
of apples was calculated by using the following
equation (Mohsenin, 1986);


 


28
2
2,1
BD
BD
AC
R
(1)
Figure 1. Radius of curvature measurement device
However, since the fruits are not full sphere in
shape, radius of curvature was calculated by taking
harmonic mean of peripheral (R
1
) and longitudinal
(R
2
) radius at impact location into consideration. In
calculations, harmonic mean was preferred rather
than arithmetic mean.
R= (2R
1
R
2
/ (R
1
+R
2
))
(2)
Impact energies of 0.064 J, 0.116 J and 0.176 J
were applied to apples with different storage
durations. Fruits were kept at room temperature for
24 hours after each test. Following the observation of
color condensation over the contact location on, a cut
was made along the longitudinal axis of the fruit.
Then the bruise diameter and depth were measured
with a digital caliper. Total bruise volume was then
calculated by using the following equation (Holt and
Schoorl, 1977).
)43(
24
)43(
24
2222 xd
x
hd
h
Vz


(3)
Where;
z
V: Bruise volume (mm
3
)
x R R d
  
2
2
4
(mm) (4)
R: Radius of curvature (mm);
d: Bruise depth (mm)
Figure 2. Bruise volume based on bruise diameter and
depth (Schoorl and Holt 1977).
ANOVA test was performed to determine the
effects of storage duration and impact energy on
bruise volume. DUNCAN multiple range test was used
to compare the means and find out the significant
differences.
RESULTS and DISCUSSION
Mean, minimum and maximum values together
with standard deviations of some physico-mechanical
properties of Fuji apples are provided in Table 2.
Table 2. Physical properties of Fuji apples
Properties Mean Min. Max. SD

.
Length (mm) 73.90 64.49 89.19 6.83
Width (mm) 82.48 71.37 91.95 5.72
Thickness (mm) 76.98 53.63 89.44 6.83
Mass (g) 238.79 178.00 322.00 7.53
Radius of
curvature (mm)
47.03 37.18 63.73 6.72
*
:
Standard deviation
Results revealed significant effects of storage
duration and applied impact energy on bruise volume
of apples at 5% (P<0.05) level. Increasing bruise
volumes were observed with increasing storage
durations and impact energies (Figure 3).

193
Figure 3. Bruise volumes as affected by storage
durations and impact energies
Bruise volumes formed by the impact energies
over three different locations of the apples based on
storage duration differences are observed. Maximum
bruise volumes were observed over stem sides of the
apples and the minimum values were observed over
the lateral sides of the apples. Effects of apple
locations on bruise volumes were found to be
significant at 5% (P<0.05) level.
Statistical information about the effects of storage
durations and impact energies applied to three
locations of the apples are provided in Table 3.
Table 3. Effects of storage durations and impact levels on bruise volume
Storage
Time
Impact Energy (J)
Apple
locations
Mean Bruise
Volume
(mm
3
)
Standard
deviation
(±)
30 days
0,064
B
89,578
22,98
L
72,012
28,33
S
117,484
21,71
0,116
B
106,286
24,80
L
88,639
26,04
S
135,170
16,57
0,176
B
281,012
79,
20
L
208,659
43,53
S
399,140
151,17
90 days
0,064
B
120,653
37,63
L
107,380
41,49
S
196,708
139,72
0,116
B
213,837
64,15
L
166,631
74,22
S
297,802
97,90
0,176
B
309,929
201,14
L
290,103
167,51
S
541,013
142,14
180 days
0,064
B
150,642
28,85
L
109,788
19,56
S
169,852
21,71
0,116
B
252,167
114,27
L
196,920
104,27
S
321,652
95,08
0,176
B
523,809
119,91
L
461,668
125,44
S
743,932
153,79

194
Means
30 days
166.44
a
117.60
90 days
258.06
b
161.78
180 days
325.60
c
218.87
0,064
126.01
a
58.75
0,116
197.68
b
101.67
0,176
426.41
c
181.32
B
189.08
a
138.39
L
236.26
ab
154.33
S
324.75
b
219.86
(B:Blossom side; L:Lateral side; S:Stem side)
CONCLUSIONS
Current findings revealed significant effects of
storage durations and impact energy levels on bruise
volumes at 5% (P<0.05) level. While the maximum
bruise volumes were observed over the stem sides of
the apples, the minimum bruise volumes were
observed over the lateral sides of the apples.
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