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Comparison of Package Cushioning Materials to

Protect Vibration Damage to Golden Delicious

ApplesAmer Eissa*1, A. H., Gamaa1. G. R, Gomaa2. F. R and Azam1. M. M

1Department of Agriculture Engineering, Faculty of Agricultural

Minoufiya University, Shibin El-Kom, EGYPT.2Department of Production Eng.& Mech. Design, Faculty of Engineering,

Minoufiya University,Shibin El-Kom, EGYPT.

Abstract- Damage to fruits and vegetables continues to

be a big challenge as global markets become a reality.

Worldwide distribution of sensitive produce is faced

with various levels of impacts from shipping and

handling. Despite a variety of packaging options

available today, bruising damage is commonplace for

post-harvest apples throughout the supply chain. The

major sources of bruising are compression, impact or

vibration forces.

Vibration simulation carried out to measure the

dynamic behavior of a apple during transporting. The

experimental program included the dynamic study on-

line. Operational modal parameter estimation was

made based on acquired data for three types of

cushioning materials (foam-net, paper-wrap and

without (control)). To assess the dynamic behavior of

package and the damage to apple due to transient

vibration during transporting and the possible effect

due to the damage of apple in package.Six identified modes were identified in the frequency

range (0-1.6 kHz) using two techniques of estimation.

Peak picking method (P-P) and robust technique

enhanced frequency domain decomposition (EFDD) are

applied to avoid harmonic components in application.

The results obtained in range control package shows

that increasing damage volume compared to paper-

warp and foam-net package, may be due to closing

harmonic frequency of mechanical element with natural

frequency of apple and this need much attention in

design the system for fruit transport trucks in attempt

to keep the resonance frequencies of fruit away from

exciting frequency of rotating system. A comparison of

experimental results of three types of cushioning

materials shows that foam-net package is more suitablefor packaging. The use of foam-net reduced the

percentage of damage fruit by (50-63%).

Key Words:Apple, Bruise volume, Vibration damage,

Cushioning materials, Modal testing,

Operational Modal Analysis.

1. Introduction

Apples are a popular and nutritious

horticultural product popular worldwide. Consumers

insist on a high quality product that is free from any

bruises, cuts, punctures, physiological disorders and

pathogens (Matzinger B, Tong C. 1993). Bruising,

which is objectionable to fresh-market consumers,

can result in a lower grade for any apple. Several

studies have been conducted internationally that

show that compression, vibration and impact forces

cause a majority of the mechanical damage, such as

bruising, to apples in the supply chain. Apples

packaged commercially undergo a series of shocks as

a result of handling and transportation. Every process

from picking of the fruit to distribution to the

consumer offers an opportunity for bruises, cuts, or

punctures. Various studies have been done todetermine the effects of picking, handling, and

transportation on damage.

The quality of fruits can be determined by

its external and internal characteristics. The most

important external characteristics are the size, shape,

smell, appearance and product presentation, and the

most important internal characteristics are the taste

and texture (Abbott and Lu, 1996; Chen & de

Baerdemaeker, 1993; Wang & Sheng, 2005). The

flesh firmness is a texture attribute and one of themajor fruit quality indicators. The demands for high

quality fruits make it necessary for growers and

distributors to set up an integrated quality controlsystem for monitoring the quality of the fruits during

picking, storage, and distribution. The traditional

destructive technique for measuring the firmness is

the Magness-Taylor firmness test with penetrometer.

This method which is defined in terms of resistance

to penetration is, however, destructive and cannot be

used for on-line control of fruit quality. Currently,

there is a growing interest in non destructive methods

for on-line sorting. Many researchers proposed some

non-destructive methods based on the dynamic

principles, such as the acoustical signal and

resonance frequency produced by the machinery

, 2044

, , (//../)

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knock and shock power, (traditional modal analysis)

which utilize eigen-frequency of fruit vibration or

shock power to measure its firmness (Abbott et al.,

1992; Schotte et al., 1999; De Belie et al., 2000;

Wang, 2003; Wang et al., 2004a; 2004b). Although

the measurements and technologies may be different,their purposes in all studies are to evaluate the

Youngs modulus of fruit firmness and obtain their

relationship. Several non destructive methods for

firmness estimation have been developed; the most

important ones are based on vibrations (Abbott, et al.,

1995), ultrasounds (Galili et al., 1993), compression

(Bellon et al., 1993) and impact forces.

Much research has been carried recently out

on assessing the effect of vibration during transport

on farm produce. The frequencies of transport

vibration have been monitored for trucks carrying

fresh fruit (Hinsch et al., 1993; Jarimopas et al.,

2005). Moreover, much attention has been paid toassessing mechanical damage to different species of

fruit and vegetables during transport, such as potato

(Turczyn et al., 1986), peaches (Vergano et al.,

1991), apples (Timm et al., 1996; Van Zeebroeck et

al., 2006), loquats (Barchi, 2002), and pears

(Berardinelli et al., 2005). It is thus well known that

one of the major causes of mechanical damage to

fresh fruit is vibration during transport between farms

and retail out lets (Remon et al., 2003).

Apples are exposed to compressive forces

via forces applied by the pickers body, tree limbs,

ladder rungs or rail, bulk bin rails and bottoms.

Compressive forces may also get applied to apples byother apples because of excessive bulk bin depth or

carton stack height, by operators forcing the cartons

shut or into a tight spot, etc (Brown 1993).Vibration

forces are the second major cause of mechanical

damage to apples in the supply chain and are almost

impossible to avoid. If the cartons or bins that carry

the apples through the distribution environment hit

resonance (their natural frequency matches the

forcing frequency of the conveyance), severe

accumulated bruise damage is inherent. Impacts

impart high forces in an extremely short duration andare often not obvious in mechanical handling systems

such as those used in packing lines. The effect of

impact forces usually results in bruises, permanentdamage and lower perceived quality. Bruise

sensitivity has also been reported to increase with

storage time (Brown 1993).

Effectiveness of

cushioning materials in protecting impact damage of

apples is the primary objective of this research.

Various packaging materials are in use today

to wrap individual apples to provide cushioning so

that they may survive the adverse distribution

environment effects. In a study, a net made of drybanana string, an agricultural waste wrapping for

apples, was shown to save the fruit from damage at

the impact energy of 1.1 J (Jarimopas et al., 2004).

This study mentioned problems of fungi attack due to

the wrapping on the skin of the fruit. Another

research studied paper that is typically applied to line

the inner surface of plastic and bamboo fruit

containers for protecting fresh fruit from bamboo cuts

and moisture loss during transport (Jarimopas et al.,

2002). Paper was found not to be a good cushioning

material against impact damage. (Peleg, 1985).

Describes good interior packaging as that which

treats a fruit as separate units, avoids fruit-to-fruitcontact, absorbs the impact energy and is practical.

At present, foam nets function well as one of the

commercial packaging solutions (Chonhenchob V,

Singh SP., 2004).However, it is not easily degradable

in a landfill.

For agriculture applications in many existing

practical case in addition to the random loads,

harmonic excitations are also present due to for

instance to the rotating components. If the frequency

of the harmonic components of the input is close to

the eigen-frequency of the fruit, damage will occur,

and OMA procedure fails to identify the modal

parameter accurately (Mohanty & Rixen, 2004;Batel, 2002; Jacobsen et al., 2007). Therefore special

attention must be paid to identify and separate

harmonic component from structural modes and

eliminate the influence of harmonic component in

modal analysis, we need robust analysis to solve

problem which cannot be solved by conventional

approach as in (Ran Zhou et al., 2007; Barchi, 2002;

Vursavus & Ozguven, 2004), they used linear (PSD),

and this spectrum cannot detect side band frequency

if there is closed frequency because of poor

resulation through the average result and it need tospecial correlation detection as in (Galvin, 2007)

used P-P method and this is good method for light

damping and for spaced modes. (Barchi, 2002;Brincker et al., 2000) used natural excitation

technique and complex expontional identification) in

the presence of harmonic excitation.

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In this paper exciter vibration with force

transducer used to investigate the fruit damage during

transport and measuring the response through

accelerometers with different types of cushioning

material were employed in simulated transporting test

in laboratory as in Fig (1a, b, c), using robust

technique to avoid harmonic component in

application this method is EFDD (Schwarz &

Richarson, 2001; Jacobsen et al., 2007) and

compared with P-P method. Three different types of

cushioning material were employed (paper-wrap

package, foam-net package and without-paper

package). The OMA procedure is based on damage

monitoring that could open the door or exploits the

automated (fruit and vegetables) damage monitoring

towards an automated fruit inspection system.

2.Experimental Procedure

Figure -1a.Schematic layout of the system used for vibrations analysis

Figure.1c.Position reference and vertical accelerometer.

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An experimental platform is created to

investigate health monitoring schemes under (OMA)

for apple using three different types of cushioning

material and two techniques for operational modal

parameters estimation, the methods included.

1- Evaluation of change in modal properties.

2- Evaluation of EFDD (Enhanced

Frequency Domain Decomposition) transmittance

function with structure subjected to high frequency

and compound mode.

2.1. Specimen Preparation

Golden Delicious Apples at commercial

maturity, according to the skin color of fruits wereselected on the basis of uniform color and absence of

bruises and disease. All of the apples (about 200 kg)

were transported to the laboratory within 2 h.

According to the commonly used storage method for

Figure 2. OMA measurement model.

Figure 3-Schematic layout of the system used for preliminary vibration analysis.

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golden delicious apples. Five fruits were selected

randomly from each group and a number was affixed

to their stem. Then, the selected apples were

transported in a refrigerated box to the laboratory

about 2 h prior to measurements.

The tested apples are taken from the main

spring crop (summer 2009, 2010), (Golden Delicious

Apples) were obtained from the Privet Farm",

samples were carefully hand harvested. All samples

stored after harvesting to a certain period, and then

tested in natural temperature after stored period.

2.2. Simulation Testing

The evaluation of the apple damage using

OMA was carried out simulating road transport in a

vibration exciter with three different of cushioning

packaging materials and two different of package

type. To simulate the transportation and random

vibration was used with force transducer.Firstly Preliminary vibration measurements

were carried out on the apple package which putted

on the exciter as shown Fig (1a). During all

measurements package apples are placed above theexciter, which generates random vibrations. Two

piezoelectric accelerometers were fixed on the two

positions one is a reference and the other moving

through a series of dots on the packaging individual

fruit apple as in Fig (2). The accelerometers were

connected to charge amplifier and (Pulse Lab shop

software 14.1.1.51) analyzer. The signals were

analyzed in the range (0-1.6 kHz) using FDD

technique (Jacobsen et al., 2007).

A frequency analysis of the signals was

carried using EFDD (Schwarz & Richarson, 2001;

Jacobsen et al., 2007) to assess the variability of

successive repeated measures of auto and cross

correlation function. Since two accelerometers were

available for the testing one of these accelerometers

is held stationary for the reference during the test Fig

(1c), where the i/p force remains unknown and may

vary between the set-ups. The reference

accelerometers is chosen in order to be able to

measure very carefully all the global mode of the

structure. To have a laboratory test for OMA

evaluation the data analysis in frequency range of

interest (0-1.6 kHz).

The apples were removed from cold storage

and inspected for any visible fruit damage in the form

of a bruise, cut, or puncture. Pre-test damage wasmarked so as to not be included in the test results.

The apples were then immediately placed into the

package with three type of cushioning materials

(paper-wrap package, foam-net package and without-

paper package) on exciter vibration table.

2.3. Data AnalysisDifferent procedures to obtain modal

parameters from the ambient vibration data have been

considered (Mohanty & Rixen, 2004; Brownjohn,2003; Brincker & Anderson, 2001; Galvin, 2007;

Figure 4 - The resonance frequencies of structure and coherence function between two signals.

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Batel, 2002; Schwarz & Richarson, 2001; Jacobsen et

al., 2007).

The applied forces are unknown; therefore,

neither the FRF nor impulse response function can be

obtained to determine modal parameters as in

classical modal analysis (Dascotte, 2002; Batel,

2002).

The signal at the fixed accelerometer is used

as a reference to determine the FRF and the impulse

response function (Caccese et al., 2004). Two

complementary identification methods have been

considered in the present work (FDD and EFDD),

based on frequency domain analysis using Matlab

tool box. Fig (4) shows the resonance frequencies of

structure and coherence function between two signals

To indicate firmness f or spherical fruit,

stiffness factor (S) or firmness index (FI) (first

Figure 5 - Peak-picking of the average normalized singular values of the complete PSD matrix.

Figure 6 - .Mode shape of package fruit during OMA tests

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introduced by Nourain Jamal, et al 2005) can be

calculated as:

S = f2m

2/ 3 (1)

where: S is the stiffness coefficient (kg2/3

s- 2

), f the dominant frequency where response

magnitude is the greatest (Hz) and m the fruit mass(g).

Gmez. A. H., et al. 2006, reviewed a

mathematical model for the interpretation of the

vibrational behavior of intact fruit. They showed

that the Elastic Modulus (or Youngs Modulus) could

be estimates satisfactorily as follows:

E = f2m

2/3

1/3 (2)

where: E is the elasticity coefficient (Pa)

and the density (kg/m3).

2.3.1. The first identification method employed is peak-picking (P-P).

Each of the SDOF systems obtained by the

singular value decomposition allows us to identify

the natural frequency and mode shape (unscaled) at a

particular peak. Using the operational modal analysissoftware, we perform the peak-picking technique

(similar to the quadrature-picking in classical modal

analysis) for each resonance on the average of the

normalized singular values for all data sets see Fig

(4). The FDD technique provided the resonance

frequencies and the mode shapes. The very well

defined deformation patterns were animated using thesoftware and exhibit very clear modal deformations.

The frequency domain decomposition provided very

good results for the resonance frequencies and the

mode shapes. It is important to note that thedeformations obtained are not true mode shapes. The

residues obtained in the mathematical derivation are

not scaled to the input force and therefore will not

provide scaled shape vectors. It is also possible to

obtain damping characteristics of each mode and

more precise resonance frequencies by using the

enhanced frequency domain decomposition based on

the determination of the correlation functions (Fig

(5).This has been used with success in many

other applications (Coucke et al., 2003; Galvin, 2007;

Brincker et al., 2000). This method is based on the

fact that when FRF reach a peak at certain frequency

it can be associated to the force or to resonance

frequency of the structure. Natural frequencies are

identified from the peaks of spectral density function

nidi .12

=

(3)

The distinguish between peaks associated

with the excitation and those associated with

resonance frequencies of the structure the coherence

function between two signal has a value close to one

for the resonance frequencies of the structure. This

fact helps to decide as shown in Fig (5 a, b) which ofthe frequencies really are the natural frequencies of

the structures, the (peak picking methods) (P-P) is

based on the assumption that the dynamic resonance

peak is determined for each mode. This valid for

well separated mode as in Fig (6) and it's difficult to

identify modes very close to each other using this

method.

2.3.2. The second identification technique used is the

Enhanced Frequency Domain Decomposition (EFDD).

The technique used in frequency domain

(Jacobsen, 2006) which, from a simple form,introduces significant improvement to the peak-

picking technique. This method based on a modal

decomposition realization of the spectral density

matrix. One of the advantages of this method beingthe possibility of identifying the very close modes.

This nonparametric technique estimates

modal parameters directly from signal processing.

FDD technique estimates the modes using

singular value decomposition (SVD) of each spectral

density matrix. This composition corresponds to

(SDOF) identification of the system for each singular

value.

The relationship between the input x (t) andthe output y (t) can be written in the following form

(Jacobsen, 2006).

( )[ ] ( )[ ] ( )[ ] ( )[ ]Txxyy jHjGjHjG = (4)

where: Gxx(j) : is the input power spectral

density matrix that is constant in the case of a

stationary Zero mean white noise input

Gyy(j) : is the output PSD matrix, and H(j)

: is the FRF matrix as in equation (2).

The FRF matrix can be written in a typicalpartial fraction from used in classical modal analysis

in term poles and residues.

( )[ ] ( )[ ]

( )[ ][ ] [ ]

k

km

k c

k

j

R

j

R

X

YjH

+

==

=

*

1

(5)

where : dkk jk +=

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m being the total number of modes. 1k

being the pole of the kthmode, skthe modal damping

and wdk the damped natural frequency of the kth

mode:

2

0 1 kkdk = (6)

Withk

kk

0

=

k being the critical damping and w0k theundamped natural frequency, both for mode k.

The (EFDD) technique allows the resonance

frequency and damping of a particular mode to

extract by computing the auto and cross correlation

functions (Schwarz & Richarson, 2001).

The free-decay time domain function (the

correlation function of the SDOF system) is used to

estimate damping for mode k:

=

pk

kk

r

r

p

0ln2

(7)

where r0k is the initial value of the

correlation function and rpk is the pth extrema. The

Figure 8. Shape of damage to the flesh of the apple

Figure 9 - Degree of damage to the flesh of the apple

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According to Table 1, foam-net packages

resulted in different frequency responses of peaks in

PD spectra from other samples. This phenomenon

could be due to the texture of foam-net packages,

which has more elasticity and springiness than paper-

wrap packages. The data in (Figure.11) indicate that

the values of the PD spectra attenuated above 200

800Hz relying on cushion materials, which showed

little effects of transport vibration in the damage to

fruits because of their low energy for higher

frequencies. Also, according to the results, there was

a very small difference between the different

cushioning materials in the vibration levels at

frequencies above 800Hz. Our data suggest that

foam-net packages were the most efficient in

alleviating vibration intensity during transport.

Vibration acceleration was determined using

PSD (Fig.11). Table (1) showed main characteristics

and peak values of power density (PD), Frequency

interval (Hz) of apples with different cushioning

materials for cartoon package, located at excitation,

during tests, which peaked at 331, 436 and 642 Hz

Figure 11. Power density (PD) spectra vs frequency (F) of the apples withdifferent cushioning materials at cartoon package

Figure.12. Typical acceleration history versus time during excitation.

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from control package, package with foam- net

Fig. 13. Vibration during excitation from package with: (a) foam- net cushioning material, (b) paper-wrap

cushioning material, (c) control, at cartoon package.

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cushioning material and package with paper-wrap

cushioning materials (Fig.11) in cartoon package.

Table 1. Main characteristics and peak values of

power density (PSD) ((m/s2)/Hz), Frequency

interval (Hz) of apples with different cushioningmaterials at carton package, located at excitation,

during tests

Package frequency

(Hz)

Peak value

((m/s2)/Hz) of PD

spectra

control 331 3.73E-2

paper-wrap

cushioning

material

642 1.23E-1

Foam- net

cushioning

material

436 1.57E-2

To determine shock and vibration during

excitation, we measured the continuous acceleration.

(Fig.12) shows a typical example of acceleration data

for 1000s. Based on careful observation of

acceleration data, we found that shocks occur

frequently (Fig.12). The acceleration amplitude of

these shocks is mostly above 2 m/s2

. These shocks

prevent the waveform from being considered random

vibration, and their acceleration level is significantly

higher than that of vibration

Typical exciter acceleration data is shown in(Fig. 13) at package (cartoon): (a) from package with

foam- net cushioning material , (b) from package

with paper-wrap cushioning material and (c) from

control package. Vibration acceleration during foam-

net cushioning material was very much lower than bypackage with paper-wrap cushioning materials.

According to Table 2, show maximum values of

acceleration of apples with different cushioning

materials for two type package. Data of vibration

acceleration at package with foam- net cushioning

material was lower than at package with paper-wrap

cushioning material and control package at cartoon

package. Our data suggest that package with foam-

net cushioning materials were the most efficient in

alleviating acceleration intensity during excitation.

Table 2. Main characteristics and maximum

values of acceleration (m/s2), time (ms) of apples

with different cushioning materials for two type

package, located at excitation, during tests

Package Time (ms) Acceleration (m/s )

Control 708 4.99E+00

paper-wrap

cushioning

material

576 8.12E+00

Foam- net

cushioning

material

769 3.48E+00

Typical exciter force data is shown in (Fig.

14) at carton package: (a) from package with foam-

net cushioning material , (b) from package withpaper-wrap cushioning material and (c) from control

package. Vibration force during foam-net cushioning

material was very much lower than package with

paper-wrap cushioning materials.

According to Table 2, show maximum

values of force of apples with different cushioning

materials for two type package. Data of vibration

force at package with foam- net cushioning material

was lower than at package with paper-wrap

cushioning material and control package at two type

of package. Our data suggest that package with foam-

net cushioning materials were the most efficient in

alleviating acceleration intensity during excitation.

3.2. Dynamic behavior of Apple duringtransporting.

The variation of vibration characteristics of

this type of apple with the correlation of its behavior

and material characteristics was investigated using

(OMA) for three types of cushioning materials. The

dynamic behavior of the simulation model of exciting

apples are governed by vertical bending and torsion

modes, in the frequency range of (0 1.6 kHz), six

modes have been identified in this frequency range.

Table ( ) shows the obtained natural frequencies and

damping loss factor for two techniques of estimation

of the model under the excitation conditions for boththree types of cushioning materials. The first test wascarried for foam-net cushioning material while the

second test for paper-wrap cushioning material and

the third was using without-paper cushioning

material for each apple. Very little change appears in

the natural frequencies obtained from the three

experimental tests, as can be seen from the values

shown in Table (3).

From measured resonance frequency, the

dynamic stiffness factor (SF) of the apple

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was calculated and described according to Eq. (1). Table 4 and Fig.(15a, b, c) show the relation

Figure. 14. Force, (N) vs. Time (ms) during excitation from package with: (a) foam- net cushioning material,

(b) paper-wrap cushioning material, (c) control, at cartoon package.

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between the resonant frequency and stiffness factor

(SF) of apple, which show that increasing stiffness

factor (SF) by increasing natural frequency for all

three type of cushioning materials at carton package.

Table 3. Main characteristics and maximum

values of force (N), time (ms) of apples with

different cushioning materials at carton package,

located at excitation, during tests

Cartoon

Package Tim

e (ms)

Force

(N)

Control 942 1.9E+

00

paper-wrap

cushioning

264 3.86E

+01

material

Foam- net

cushioning

material

815 1.06E

+00

From measured resonance frequency, the

dynamic modulus of elasticity of the apple was

calculated and described according to Eq. (2). Table

4 and Fig.(15a, b, c) show the relation between the

resonant frequency and modulus of elasticity (E) of

apple, which show that increasing modulus of

elasticity (E) by increasing natural frequency for all

three type of cushioning materials at carton package.

Table (3). Determining resonance frequency and damping ratio with foam-net of cushioning materials.

Mode Frequency

Hz

Damping Ratio

%

Elasticity, E

MPa

Stiffness, S

104Hz

2kg

2/3

EFDD Mode, 1 15.81 4.759 0.0042 0.0576

EFDD Mode, 2 68.92 4.402 0.0800 1.0950

EFDD Mode, 3 121.9 6.2570.2503 3.4255

EFDD Mode, 4 275.3 0.11381.2767 17.4713

EFDD Mode, 5 323 2.8171.7574 24.0501

EFDD Mode, 6 410.8 1.0782.8427 38.9021

EFDD: Enhanced Frequency Domain Decomposition

Table (4). Determining resonance frequency and damping ratio with paper-wrap of cushioning materials.

Mode FrequencyHz

Damping Ratio%

Elasticity, EMPa

Stiffness, S10

4Hz

2kg

2/3

EFDD Mode 1 24.13 4.093 0.0098 0.1342

EFDD Mode 2 77.67 2.716 0.1016 1.3907

EFDD Mode 3 142.1 4.896 0.3401 4.6548

EFDD Mode 4 249.3 5.088 1.0469 14.3270

EFDD Mode 5 342.8 1.53 1.9795 27.0890

EFDD Mode 6 370.9 2.446 2.3173 31.7122

Table (5). Determining resonance frequency and damping ratio of without paper cushioning materials.

Mode Frequency

Hz

Damping Ratio

%

Elasticity, E

MPa

Stiffness, S

104

Hz2

kg2/3

EFDD Mode 1 18.63 6.706 0.0058 0.0800

EFDD Mode 2 28.23 4.795 0.0134 0.1837

EFDD Mode 3 131.9 3.74 0.2931 4.0105

EFDD Mode 4 209.4 4.813 0.7386 10.1080

EFDD Mode 5 380.2 4.552 2.4350 33.3224

EFDD Mode 6 556.2 1.581 5.2111 71.3139

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Fig.14a. Relation between the stiffness factor and natural frequency of package with foam-net cushioning materials

Fig.14b. Relation between stiffness factor and natural frequency of package with paper-wrap cushioning materials

Fig.14c. Relation between the stiffness factor and natural frequency of package without paper cushioning materials

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Fig.15a. Relation between the stiffness factor and natural frequency of package with foam-net of cushioning materials

Fig.15b. Relation between the stiffness factor and natural frequency of package with paper-wrap of cushioning

materials

Fig.15c. Relation between the stiffness factor and natural frequency of package without paper cushioning materials

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3.3. Evaluation of vibration damageIn the current study, the apples were

exposed to severe vibration and extended transit time.

Injuries to apples included darkened burnings of the

skin and bruises with little or no penetration into the

flesh. (Fig. 16) gives the results of damage evaluationof the apples with different cushioning materials. The

greatest damage was noted in the apples without

cushioning materials. Similar to what was seen with

vibration levels, the use of foam-net packages was

more efficient at reducing damage to individual

apples than paper-wrap packages.

Both of the cushioning materials

efficaciously reduced severe and moderate damages

per fruit (Fig. 16). However, the average number ofbruises in the slight range for apple with paper-wrap

packages was more than that for apples without

packages. This was because the apples with paper-

wrap packages turned many severe and moderate

bruises into slight bruises for their protective effects.Foam-net packages were still more effective at

decreasing severe and moderate damages than paper-

wrap packages. This phenomenon was not solely due

to the placement of a layer of cushioning materialsbetween each fruit, but may also be related to their

ability to decrease vibration levels during transport.

Clearly, foam-net packages had more protective

effect than paper-wrap packages. The estimated

percentage of the average number of bruises apples

were at without paper packages (8.49%), apples with

paper-wrap packages (3.59%) and apples with foam-

net packages (1.91%). (Gentry et al, 1965) reported

that vibration bruising affected fruit appearance

provided a point of entry for decay organisms and

increased moisture loss from the fruit. According to

the results, relatively lower bruise area for apples

Table (6). The difference in % of damage wall.

Type of package Damage

(%)

Change of damage skin

Bruise Area

(mm2)

Bruise Volume

(mm3)

Bruise Spot Ratio

(BSR, %)

Control 63 75.21 1269.45 21.35paper-wrap cushioning 45 41.80 672.15 14.25

Foam- net cushioning 36 23.98 382.56 7.6

Figure16.The average number of bruises apples with different types of cushioning materials.

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with foam-net contributed to keeping the quality of

fruits better during the storage after transport. The bruise spots have characteristic shapes

Figure 17.The bruises area of apples with different types of cushioning materials during excitation

test.

Figure 18.The bruises volume of apples with different types of cushioning materials during

excitation test.

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expressed by bruise spot ratio (BSR), the ratio of the

bruise spot thickness (d) to the bruise spot diameter

(D). Our results are concentrated in Table (6). The

bruises obtained in the package foam-net had rather

lower bruise spot ratio than paper-wrap and control

package.Fig 17. Show the relation between bruise

area of apple and storage period which increased by

increasing period of storage in three type of

cushioning materials. Therefore, most of the

vibration forces transmitted from the vibration table

to the apple package are damped by the apple in the

package and cause bruising of the apple. The reason

for these bruises can be attributed to the fact that such

forces in the apples are higher, causing some of the

apples to be periodically weightless. Weightlessness

allowed the apples to rotate and to bump against each

other. This movement caused the surface

discoloration and cell wall fatigue, and consequentlybruising damage in apples according to (Amer Eissa,

A.H. and Gomaa, F. R, 2009).

Data presented in Fig (18) and table (6)

showed that increasing in the bruise volume

(damage) at different cushioning materials at

increasing storage period for apple at carton package

see fig. 18. The bruise volumes obtained in the

package foam-net had rather lower bruise volumes

than paper-wrap and control package see table (6).

4. CONCLUSION

1- Foam-net packages shows the practical use of

vibration absorber as a quality assessment

technique for apple to reduced the transport

vibration levels and it was more effectively than

paper-wrap packages.

2- The use of foam-net packages also reduced the

mechanical damage to individual apple during

transport, compared with paper-wrap packages

3- Fruit bruising is one of the most important

factors limiting mechanization and automation in

harvesting, sorting and transport of soft fruit and

vegetables. Bruise extent is usually described in

terms of bruise volume, which is closely related

to product quality. The most important bruise

factor in every case is the loading extent, which

is usually expressed in the terms of loading

energy or absorbed energy.

4- The technique allows a very fast measurement

on-line (OMA) technique allows a scientist,

technician, or engineer to perform a modal

investigation easily, quickly and accurately. It

can be accomplished by only measuring the

response of the structure subjected to unknown

and unmeasured force furthermore, since the

technique is based on the vibration of the pear as

a whole, a global quality parameters is found,

this in contrast with several classical techniques

that are used to assess fruit quality (for instance

penetrometer or firmness values) that only givelocal information.

5- Due to the damping characteristic of apple and

effect of intersect of dominant harmonic

component in the measured responses (which is

unavoidable in many applications of OMA).

EFDD is a robust estimation of the resonant

frequency of the six modes and damping ratio

was used, based on smoothing of the frequency

spectrum (coherence) and spaced mode to sure

that there are not leakage exist and there for the

inverse test time are successively obtained.

6-

The selection of location and direction for the

force excitation and the response measurementsensor are most important for detecting a mode.

7- The dynamic characteristics of the fruit species is

an important factor in determining the causes of

in transient fruit damage during transporting, this

need much attention in research, the importance

of fruit natural frequency in design of the

suspension system for fruit transport trucks in

attempent to keep the resonance frequencies of

truck away from the range of fruit resonance

frequency and to design cushioning package to

protect an item (fruit) of known strength from

known shock and vibration.

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