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Selected Mechanical and GeometricProperties of Different Almond CultivarsEbubekir Altuntas a , Resul Gercekcioglu b & Cemal Kaya ca Department of Agricultural Machinery, Agricultural Faculty ,Gaziosmanpasa University , Tokat, Turkeyb Department of Horticulture, Agricultural Faculty , GaziosmanpasaUniversity , Tokat, Turkeyc Department of Food Engineering, Agricultural Faculty ,Gaziosmanpasa University , Tokat, TurkeyPublished online: 03 Mar 2010.

To cite this article: Ebubekir Altuntas , Resul Gercekcioglu & Cemal Kaya (2010) Selected Mechanicaland Geometric Properties of Different Almond Cultivars, International Journal of Food Properties,13:2, 282-293, DOI: 10.1080/10942910802331504

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International Journal of Food Properties, 13: 282–293, 2010Copyright © Taylor & Francis Group, LLCISSN: 1094-2912 print / 1532-2386 onlineDOI: 10.1080/10942910802331504

282

SELECTED MECHANICAL AND GEOMETRIC PROPERTIES OF DIFFERENT ALMOND CULTIVARS

Ebubekir Altuntas1, Resul Gercekcioglu2, and Cemal Kaya3

1Department of Agricultural Machinery, Agricultural Faculty, GaziosmanpasaUniversity, Tokat, Turkey2Department of Horticulture, Agricultural Faculty, Gaziosmanpasa University,Tokat, Turkey3Department of Food Engineering, Agricultural Faculty, Gaziosmanpasa University,Tokat, Turkey

The effects of compression in different axes and speeds on mechanical properties andselected geometric properties of almond cultivars were investigated. The average sphericity,volume and surface area ranged from 60.5 to 71.1%; 3.52 to 3.81 cm3 and 0.60 to 0.61 cm2

for almond cultivars. The greatest and least rupture force of almond were obtained alongthe X and Z axes for each cultivar. The results indicated that the effects of compressionalong the axis and speed on the rupture force were highly dependent on almond cultivars.Selected mechanical properties were affected by geometric and mechanical parameters ofalmond cultivars.

Keywords: Almond cultivars, Geometric and mechanical properties.

INTRODUCTION

Almond is widely growing in Anatolia and Turkey with an annual production ofabout 45.000 tons.[1] Almond harvesting and cracking are still done manually, whichincreases processing time and cost for kernel extraction in Turkey. In order to designequipment used in harvesting, transporting, storing, cracking, handling, and processing ofnuts and kernels of almonds; the geometric and mechanical properties of local almondsshould be determined. In the design of almond cracking and grinding machine, mechani-cal properties of nut and kernels are important to know.

In postharvest, the most important operation is nut cracking to extract kernel fromthe almond nut. Shell hardness of almond nut changes in relation to almond cultivars andthe cracking operation is affected by geometric and mechanical properties of almond cultivar.Compression orientation and speed affect the amount of force applied to crack almonds.Thus, postharvest processes such as cracking and grinding systems must be designed basedon the geometric and mechanical properties. Harvesting and handling of the almond are carriedout manually. The threshing is usually carried out on a hard floor with a homemade

Received 26 February 2008; accepted 09 July 2008.Address correspondence to Ebubekir Altuntas, Department of Agricultural Machinery, Agricultural

Faculty, Gaziosmanpasa University, 60240 Tokat, Turkey. E-mail: ealtuntas@gop.edu.tr

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MECHANICAL AND GEOMETRIC PROPERTIES OF ALMOND 283

threshing machine. For optimum threshing performance, processes of pneumatic convey-ing, storing and other processes of almond nut, its geometric properties and mechanicalproperties must be known.[2]

The mechanical properties of agricultural materials are necessary in designingand effective utilization of the equipment used in the transportation, processing, pack-aging and storage of agricultural products. Several researchers have investigated thephysical and mechanical properties of various crops such as macadamia nut[3] ; castornut[4] ; raw cashew nut[5] ; hazelnuts[6,7] ; arecanut kernel[8] ; groundnut kernel[9] ; almondnut and kernel[2] ; shea nut[10] ; pine nuts[11] ; mangoes[12] ; peach[13] ; peanut[14] andwalnut.[15,16]

Dursun[17] reported the compression position influenced the amount of forceapplied to crack of walnuts and other nuts. Additionally, the above author reportedthat the cracking position had an important on various nuts. Oloso and Clarke[18] eval-uated the effect of moisture content, pre-damage cultivar, and direction of loading onrupture force, rupture energy and rupture deformation under compression tests forroasted cashew nuts. Liu et al.[19] reported the cracking behaviour of macadamia nut’sshell by theoretically and numerically. Gurhan et al.[20] evaluated the mechanicalbehaviour of three apricot cultivars under compression loading at three axes and dif-ferent deformation speeds. Guner et al.[7] evaluated the mechanical behaviour ofhazelnut cultivars under compression loading and two deformation rates to determinethe rupture force, specific deformation and rupture energy required to initiate nut andkernel rupture.

Limited researchs have been conducted on the mechanical properties of almond.Some engineering properties of almond, such as rupture strength, sphericity were reportedby Kalyoncu[21] ; Aydin.[2] However, there is insufficiency of technical information anddata of different cultivars of almond in the scientific literature with regards to the mechan-ical behaviour of almond nut under different compression axis and compression speed.The objective of this study was to investigate the effect of compression speed and axis onmechanical behaviour and selected geometric properties such as size dimension, sphericity,unit mass and surface area of almond cultivars (Nonpareil, Picantili, and Drake). Themechanical properties examined were rupture force, specific deformation, absorbedenergy and required power to rupture.

MATERIALS AND METHODS

The almonds were obtained from the production of 2007 and almond orchard ofGaziosmanpasa University in Tokat, Turkey. The almond orchard was arid and nonirrigated. Almond trees’ ages are for five years. The almond cultivars used in the study arethe international cultivars. Nonpareil and Drake cultivars are originated from USA andPicantili cultivar is from Russian.[23] The almond samples were cleaned to remove impuri-ties, damaged, and broken nuts. The dimensions, sphericity, unit mass, volume, surfacearea of almond nut and kernel were determined. The moisture content of the almond nutand kernel samples were determined using the method recommended by Braga et al.[3]

The tests were carried out on almonds at moisture contents of nut and kernel 9.74 and3.87% (Nonpareil); 9.54 and 5.31% (Picantili); 9.79 and 4.71% d.b (dry basis; Drake),respectively.

To determine the average size of the almond, a sample of 100 almonds was selectedrandomly. The length, width, and thickness of almonds were measured. Along the three

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284 ALTUNTAS, GERCEKCIOGLU, AND KAYA

major perpendicular axes, the dimensions of the almond were measured by a dial-micrometer to an accuracy of 0.01 mm. To obtain the unit mass, each nut and kernel wereweighted with an electronic balance to an accuracy of 0.001 g. The geometric mean diam-eter (Dg), sphericity (Φ) and volume (V) of almond were calculated by the following rela-tionships.[2,24]

where, L is the major axis dimension, W is the minor axis dimension and, T isthe thickness in mm. The surface area of almond nut was found by analogy with asphere of same geometric mean diameter, using expression cited by Olajide and Ade-Omowaye:[24]

where S is the surface area in mm2; and Dg is the geometric mean diameter in mm. Abiological materials test device was used to determine the mechanical properties ofthe almonds tested. This device (Zwick/Roell, Instruction Manual for Materials Test-ing Machines/BDO-FB 0.5 TS) have three main components: a moving platform,a driving unit and a data acquisition (load cell, PC card and software) system.[25]

Compression force was measured by the data acquisition system. The almond nutsample was placed on the moving platform and loaded at three compression speeds(50.4, 100.2 and 199.8 mm/min) and pressed with a plate fixed on the load cell untilthe nut ruptured. These speeds are relevant to the studies conducted by severalresearchers.[15,16,26] It was assumed that rupture occurred at the bio-yield point, whichis the point on the force-deformation curve in which there was a sudden decrease inforce. From the compression speed and time, almond shell deformation was recordedand ruptures force (F) and deformation (D) was measured directly from the plottedforce-deformation curve (Fig. 1). As the compression begin and progressed, a force-deformation curve was plotted automatically in relation to the response of eachalmond nut. The force-deformation curves obtained at each loading axis and compres-sion speed level for the three almond cultivars. Samples were compressed along X, Y,and Z axes to determine the rupture force, specific deformation, absorbed energy andrequired power for cracking. The X axis (force Fx) is the longitudinal axis (length), theY axis (force Fy) is the transverse axis (width) at right angles to the X axis in the planeof the suture, and the Z- axis (force Fz) is the transverse axis (thickness) at rightangles to the plane of the suture (Fig. 2). The specific deformation was obtained fromthe following equation:

D LWTg = ( ) ,/1 3 (1)

Φ =⎡

⎣⎢

⎤

⎦⎥ ×

D

Lg

100, (2)

V LWT=p6

( ), (3)

S Dg= p 2 , (4)

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MECHANICAL AND GEOMETRIC PROPERTIES OF ALMOND 285

where e is the specific deformation in %; Lu is the undeformed almond dimension on thedirection of the compression axis in mm; and Lf is the deformed almond dimension on thedirection of the compression axis in mm.[3] Absorbed energy (Ea) by the sample at rupturewas determined by calculating the area under the force-deformation curve from the fol-lowing equation:

Figure 1 Example of experimental force-deformation curve of almond nut in the study.

Figure 2 Representation of the three axial forces (Fx, Fy, and Fz axial forces) and three perpendicular dimen-sions of almond nut.

e =−⎡

⎣⎢

⎤

⎦⎥ ×

L L

Lu f

u

100, (5)

EF D

a = ⎡⎣⎢

⎤⎦⎥2

, (6)

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286 ALTUNTAS, GERCEKCIOGLU, AND KAYA

where, F is the rupture force and D is the deformation at rupture point.[3,15] The requiredpower for cracking was calculated as belows:

where, P is required power for cracking in W; Ea is absorbed energy in mJ; Vc is compressionspeed in mm/min and D is deformation up to cracking point in mm.[15] In this experiment,a total sample of 270 almond nuts were used, the data was analyzed using a randomizedcomplete block design with split block. In this design, the main factor is almond cultivarand sub-factor is compression axis and speed. Results were analyzed using analysis ofvariance and the means were compared using LSD test as described by Gomez andGomez.[27]

RESULTS AND DISCUSSION

Geometric Characteristics

The average nut and kernel size dimensions of the three almond cultivars werepresented in Table 1. The mean values of unit masses of nut and kernel for Nonpareil,Picantili and Drake almond cultivars were 2.30, 0.89 g; 2.77, 1.07 g, and 2.00, 0.81 g,respectively. The greatest values of unit mass of almond nuts were obtained for Picantilifollowed by Nonpareil and Drake cultivars, respectively. Arslan and Vursavu4[28] reportedthat Ferragnes, Ferradual, and Guara nut masses (3.67, 3.95, and 4.01 g) were slightlyhigher than those of reported in this study.

PE V

Da c= ⎡

⎣⎢⎤⎦⎥60000, (7)

Table 1 Some geometric properties of almond cultivars.*

NUT Nonpareil Picantili Drake

Length (mm) 27.11 ± 0.28 31.26 ± 1.62 27.09 ± 0.67Width(mm) 18.90 ± 0.22 19.26 ± 1.70 18.53 ± 0.43Thickness (mm) 14.13 ± 0.14 11.51 ± 2.18 13.38 ± 0.35Geometric mean diameter (mm) 19.28 ± 0.83 18.95 ± 2.64 18.76 ± 1.09Unit mass (g) 2.30 ± 0.07 2.77 ± 0.27 2.00 ± 0.01Sphericity (%) 71.13 ± 1.65 60.45 ± 3.83 69.36 ± 4.27Shell thickness (mm) 1.94 ± 0.05 2.31 ± 0.20 1.89 ± 0.04Surface area (cm2) 0.61 ± 0.03 0.60 ± 0.08 0.59 ± 0.03Volume (cm3) 3.81 ± 0.52 3.80 ± 1.45 3.52 ± 0.60KERNELLength (mm) 20.59 ± 0.09 25.78 ± 0.62 20.09 ± 0.53Width(mm) 11.27 ± 0.09 13.43 ± 0.35 11.24 ± 0.23Thickness (mm) 8.49 ± 0.06 7.29 ± 0.08 8.15 ± 0.14Geometric mean diameter (mm) 12.50 ± 0.35 13.57 ± 0.72 12.20 ± 0.52Unit mass (g) 0.89 ± 0.04 1.07 ± 0.01 0.81 ± 0.06Sphericity (%) 60.77 ± 2.29 52.72 ± 1.88 60.83 ± 1.66Surface area (cm2) 0.39 ± 0.01 0.43 ± 0.02 0.38 ± 0.016Volume (cm3) 1.03 ± 0.09 1.33 ± 0.21 0.96 ± 0.12

* Measurements were made with 10 replicates, numbers following ± are standard deviations.

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MECHANICAL AND GEOMETRIC PROPERTIES OF ALMOND 287

The average length (27.11, 31.26, and 27.09 mm), width (18.90, 19.26, and 18.53mm), thickness (14.13, 11.51, and 13.83 mm), and geometric mean diameter (19.28,18.95, and 18.76 mm) of the Nonpareil, Picantili and Drake nuts were recorded in thisexperiment, respectively. The greatest values of dimension of almond nut and kernelswere obtained for Picantili followed by Nonpareil and Drake cultivars, respectively.

The mean values of sphericity for almond cultivars were 71.1% for Nonpareil,60.5% for Picantili, and 69.4% for Drake cultivar respectively. The highest value of sphe-ricity for almond nut was obtained from Nonpareil cultivar. The mean values of surfacearea of nut of Nonpareil, Picantili and Drake cultivars were 0.61 cm2, 0.60 cm2, and 0.60cm2, respectively. The obtained values of surface area were similar for each cultivar. Themean shell thickness of almonds were 1.94, 2.43 and 1.89 mm for Nonpareil, Picantili andDrake cultivars, respectively (Table 1). Aydin[2] reported shell thickness of almond (2.61mm) are slightly higher than those of reported in this study.

Mechanical Properties

Rupture Force. The force required to initiate nut rupture in samples with varyingalmond cultivars along the three different compression axes is presented in Fig. 3. Thelower force required to initiate nut rupture along the Z axis were obtained for Nonpareil,Picantili and Drake cultivars. The rupture force of almond nut decreased from 467.9 to341.8 N, 483.0 to 289.7 N, and 443.6 to 264.12 N as the compression speed increasedfrom 50.4 to 199.8 mm/min for Nonpareil, Picantili, and Drake, respectively. The resultsindicated that the rupture force along all three axes is highly dependent on cultivar overthe compression speed ranges that were investigated. Greater force was required to ruptureof nuts with Nonpareil cultivar being tested at the lower compression speed. The ruptureforce of almond decreased as the compression speed increased from 50.4 to 199.8 mm/min for all three almond cultivars. The greatest force was required to rupture kernels withPicantili cultivar as 483.0 and 469.9 N when loading along X axis at 50.4 and 100.2 mm/min compression speeds, respectively. These results might have concluded from thehigher values of shell thickness of Picantili than the other cultivars. Rupture force ofPicantili cultivar increased as its shell, dimension, and compression speed increases.

Figure 3 Effects of cultivar, compression axis and speed on rupture force of almond nut (N).

0

100

200

300

400

500

600

700

X- axis Y- axis Z - axis X- axis Y- axis Z - axis X- axis Y- axis Z - axis

Nonpareil Picantili Drake

Almond cultivars

Rup

ture

forc

e (N

)

50.4 mm/min100.2 mm/min199.8 mm/min

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288 ALTUNTAS, GERCEKCIOGLU, AND KAYA

Borghei et al.[29] reported the importance of walnut compression axis and dimensioneffect on the rupture force and deformation among walnut cultivars. They also reportedthe rupture force and deformation increased while walnut dimension increased. Khazaeiet al.[15] reported the compression speed, nut dimension and compression orientation hadsignificant effects on cracking force and required power to fracture. Required force to rup-ture the almond increased as shell, dimension and compression speed increased. It is alsoreported by Khazaei et al.[15] that the higher rupture force for big almonds may be due totheir thicker shell.

The loading axis with the least resistance to rupture force of almond was the Z-axis.The rupture force of nut measured when loading along the suture thickness (Z-axis) wasobtained from 376.2 to 347.8 N (Nonpareil), 325.3 to 289.7 N (Picantili), and 353.7 to264.1 N (Drake) cultivar at the 50.4, 100.2, and 199.8 mm/min compression speeds,respectively. The higher rupture forces of almond required when loading along the X-axiswere found for all three almond cultivars. The lowest rupture force for almond nut wasobtained as 264.1 N for Drake cultivar loading along Z axis at 199.8 mm/min compressionspeed. Generally, the lower rupture force for almond nut was obtained at 199.8 mm/mincompression speed for all three almond cultivars.

The effects of cultivar, compression speed and axis on rupture force were significant(P < 0.01). In this study, cracking of almond nut along X axis requires the greater forcethan along the Y and Z axes. Dursun[17] reported the average rupture forces for requiredcracking of almonds at longitudinal axis through the hilum (X), right angles to the longitu-dinal axis (Y axis) and along the suture line (Z axis) were obtained as 209.1, 244.6 and149.4 N, respectively.[17] Khazaei[15] reported the mean rupture force values of almondschanged 778 N, 626 N and 549 N along the 5, 100 and 200 mm/min loading rate, respec-tively.[15] Aydin[2] reported that the maximum rupture forces required to crack almondswere occurred along the longitudinal axis (X). Koyuncu et al.[30] reported that the maxi-mum and minimum forces required to crack walnuts (Yalova-3 cultivar) were occurred atright angles to the longitudinal axis and along the longitudinal axis. They determined theeffects of compression orientation, geometric mean diameter and shell thickness of walnuton the rupture force. They found the rupture force loading along X axis required less forceand yielded the best kernel extraction quality for walnut cultivars. Koyuncu et al.[31]

reported that the average rupture forces required to crack almonds at longitudinal axisthrough the hilum (X) obtained as 246.7 and 167.4 N for Bilecik and Sebin walnut culti-vars, respectively. Kilickan and Guner[32] ; Sharifian and Derafshi [26] reported that, therupture force increased as compression speed, shell thickness, fruit and pit size increasedfor olive and walnut.

Specific deformation. The mean values of specific deformation of almonds arepresented in Figure 4. The specific deformation decreased along the compression axis asthe compression speed increased. The specific deformation values for almond cultivarsranged from 17.2 to 14.4% (Nonpareil), 18.5 to 13.8% (Picantili), and 20.1 to 20.0%(Drake) as the compression speed increased through the three test speeds, respectively.The results show that the specific deformation along any of the X-, Y- and Z- axes is highlydependent on the almond cultivar over the range of compression speeds investigated.

The specific deformation value was found that loading along Y axis for Drake culti-var was higher than the other cultivars. The lowest specific deformation value (10.81%)was obtained for Drake cultivar loaded along Z axis. The loading axis that yielded the leastspecific deformation was the Z-axis. The specific deformation measured while loadingalong the right angles to the longitudinal axis (Y-axis) ranged from 19.7 to 17.7% (Nonpareil);

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MECHANICAL AND GEOMETRIC PROPERTIES OF ALMOND 289

19.7 to 16.1% (Picantili); and 26.12 to 25.6% (Drake) cultivar, respectively. The highestspecific deformation values were observed for each almond cultivar when loading alongthe Y-axis. Statistical analysis showed that the specific deformation differences among thealmond nuts were significant for cultivar, compression axis and compression speed weresignificant. Guner et al.[7] reported that the maximum and minimum specific deformationof hazelnut cultivars were occurred at Z axis (8.65%) and X axis (5.48%). These results forhazelnuts are slightly higher than those of reported for almond in this study. Koyuncuet al.[30] reported the specific deformation was inversely correlated with shell thickness forlength and was found to be weak for width and suture position. They also reported thespecific deformation was required to crack as geometric mean diameter increased. Bragaet al.[3] reported similar results for macadamia nuts.

Absorbed energy. The absorbed energy of rupture decreased along the compres-sion axis as the compression speed increased in the three almond cultivars (Fig. 5). The

Figure 4 Effects of cultivar, compression axis and speed on specific deformation e (%)of almond nut.

0

5

10

15

20

25

30

35

X - axis Y - axis Z - axis X - axis Y - axis Z - axis X - axis Y - axis Z - axis

Nonpareil Picantili Drake

Almond cultivars

Spe

cific

def

orm

atio

n (%

)

50.4 mm/min100.2 mm/min199.8 mm/min

Figure 5 Effects of cultivar, compression axis and speed on absorbed energy Ea (mJ) of almond nut.

0

200

400

600

800

1000

1200

1400

1600

X - axis Y - axis Z - axis X - axis Y - axis Z - axis X - axis Y - axis Z - axis

Nonpareil Picantili Drake

Almond cultivars

Abs

orbe

d en

ergy

(m

J)

50.4 mm/min 100.2 mm/min 199.8 mm/min

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290 ALTUNTAS, GERCEKCIOGLU, AND KAYA

results indicate that the absorbed energy along any of the test axis is generally highlydependent on the compression speed and almond cultivar tested. The higher absorbedenergy of almond was obtained for Nonpareil, Picantili and Drake cultivars along theX-axis (Fx) than those loaded along the other axes. The effects of cultivar, compressionspeed, and axis on absorbed energy were significant (P < 0.01). The absorbed energyvalues of almond ranged from 1229.9 to 289.4 mJ (Nonpareil), 1096.4 to 270.7 mJ (Picantili)and 1298.9 to 153.2 mJ (Drake) when loading along the compression axis tested. Theabsorbed energy values for Nonpareil were lower than those Picantili and Drake cultivars.The results might have concluded from the higher values of geometric mean diameter ofNonpareil cultivar.

Similarly, Koyuncu et al.[30] reported the rupture energy decreased with increase ingeometric mean diameter and correlated negatively. They also reported the maximum andminimum energy required to crack walnuts (Yalova-3 cultivar) occurred at right angles tothe longitudinal axis (0.440 J) and along the suture positions (0.273 J). Koyuncu et al.[31]

reported the average absorbed energy required to crack walnuts at longitudinal axis throughthe hilum (X) obtained as 0.46 and 0.07 J for Bilecik and Sebin walnut cultivars, respec-tively. Khazaei et al.[15] reported the mean absorbed energy values of almonds ranged from540 mJ, 482 mJ and 450 mJ along the 5, 100 and 200 mm/min loading rate, respectively.They also reported the absorbed energy increased with increasing almond dimension, shellthickness increased as the compression speed increased, but decreased with further increasein compression speed. Saiedirad et al.[33] reported the rupture force and absorbed energydecreased as compression speed increased. They investigated the interaction effect of ori-entation, size, and moisture content on rupture energy. The lowest difference in absorbedenergy among different levels of moisture content was related to large size.

Power of cracking. Power of cracking values determined along the X axis werehigher than those observed for either the Y and Z axes (Fig. 6). And also the power ofcracking observed when testing almond nuts along the X axis was greater than that of theother axes tested at the higher compression speeds. The effect of the cultivar, compressionaxis and speed on power of cracking was significant (P < 0.01). The loading axis with thelowest values for power of cracking was the Z-axis.

Figure 6 Effects of cultivar, compression axis and speed on required power for cracking P (W) of almond nut.

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

X - axis Y - axis Z - axis X - axis Y - axis Z - axis X - axis Y - axis Z - axis

Nonpareil Picantili Drake

Almond cultivars

Pow

er o

f cr

acki

ng (

W)

50.4 mm/min 100.2 mm/min 199.8 mm/min

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MECHANICAL AND GEOMETRIC PROPERTIES OF ALMOND 291

Power of cracking measured while loading along longitudinal axis (X-axis) rangedfrom 0.20–0.73 W (Nonpareil), 0.20–0.67 W (Picantili), and 0.18–0.65 W (Drake) cultivar,respectively. The lowest power of cracking values changed from 0.17–0.58 W (Nonpareil),0.14–0.48 W (Picantili), and 0.15–0.44 W (Drake) when loading along the Z- axis for thethree compression speed categories tested. The power of cracking values for almondcultivars tested in the X-axis were higher than almonds tested in the Y and Z axes. Themean power required of cracking values of almonds ranged from 0.04 W, 0.81 W, and1.15 W along the 5, 100, and 200 mm/min loading rate, respectively.[15] These results areslightly higher than those of reported for almond in this study. Khazaei et al.[15] reportedthe required power for cracking increased with increasing almond dimension and the com-pression speed. The difference between power of cracking big and medium almonds wasnot statistically significant.

CONCLUSION

The geometric characteristics and mechanical properties of almond cultivars weredetermined. The greatest values of size dimension were obtained for Picantili cultivar,whereas, sphericity and surface area values were for Nonpareil cultivar. The mechanicalbehaviour of almond cultivars to crack was determined by measuring the average ruptureforce, specific deformation, absorbed energy and power of cracking along the X, Y, and Zaxes at different compression speeds. The greatest amount of force required to crack thenut was required when nuts were loaded along the X-axis and the least compression forcewas required along the Z-axis for Nonpareil, Picantili, and Drake cultivars. The highestrupture force occurred for Nonpareil loaded on the X axis among the three almond cultivars,whereas the highest specific deformation and absorbed energy obtained for Drake cultivar.The results indicated that when testing the effect of compression axis on the rupture forceis highly dependent on almond cultivars. The lowest force needed to rupture of almondwas found with Drake at 199.8 mm/min compression speed among almond cultivars. Thelowest force and absorbed energy for initiation of rupture were obtained in Drake cultivaras compared to other cultivars. Rupture force decreased with an increase in compressionspeed ranged from 50.4–199.8 mm/min. The power of cracking values for almondcultivars tested in the X-axis was higher than Y- and Z-axes. The lowest power required torupture of almond was found in almond cultivars with Drake that were tested at 199.8 mm/min compression speed. The selected mechanical properties such as rupture force, specificdeformation, absorbed energy and required power to crack for almond were affected bythe geometric mean diameter, shell thickness and compression axis and speed.

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