Thermal And Dynamic Mechanical Properties Of Tomato Peel Biology Essay

Tomato Lycopersicon esculentum Mill. is one of the most popular fruit among the universe because of its alimentary constituents such as vitamin C and lycopin. As the largest tomato manufacturer in the US, California produces 13.3 million dozenss tomatoes in 2009 which deserving 1200 million dollars in sum ( California tomato agriculturist association ) . Most of the tomatoes are processed into value-added nutrient merchandises, such as catsup, paste, tomato sauce, diced tomatoes and so on ( ) . Skining operation is one of the H2O consuming and energy intensive stairss among tomato processing, which causes environmental concerns due to the big sum uses of chemicals and therefore bring forthing waste H2O. Hot H2O and lye ( Sodium hydrated oxide ) are normally used in the desquamation procedure, which therefore introduce waste H2O and chemicals to be processed earlier drained off to avoid ( ) .

Infrared dry-peeling engineering has been successfully used to skin tomato ( xuan ) . This dry desquamation method treats the tomato surface straight without any warming medium and chemicals therefore to salvage H2O and energy. However, the mechanism behind infrared desquamation is non good understood ( ? ) . Two possible grounds could be assumed. One is the Peel construction was modified or partially destroyed to do the Peel break. The other one is the relaxation of the connexion between the Peel and the out bed flesh.

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The mechanical belongingss of tomato Peel have been studied for both agronomic and processing intents. The agriculturist may desire the Peel to be steadfast plenty, since the midst Peel with high stiffness could defy the mechanical affects from surface cleft during reaping or transit, while the consumer need the Peel to be thin and soft for better gustatory sensation ( Hetzroni et al. , 2011 ) . The nutrient industries may besides prefer the house tomato tegument to be easy peeled and collected. The tensile measuring was proofed to be sufficient for the analysis biomechanical features of tomato Peel ( Hetzroni et al. , 2011 ) . It was found that the mechanical belongingss showed big fluctuation between different assortments, and the tensile measuring was independent from the punch measuring. The tomato tegument consists of an external epidermal bed and two to four beds of thick-walled hypodermal cells with collenchymalike thickener ( Ho & A ; Hewitt, 1986 ) . The cuticle has been suggested to be the fruit constituent commanding mechanical strength, which is related to checking and puncture opposition. The mechanical belongingss of ripe tomato tegument under uniaxial tenseness have been characterized by strength, strain at failure, overall stiffness and grade of stiffening. It was found that mature tomato tegument was stronger in the transverse than the longitudinal way ( Hershko et al. , 1994 ) , which meant that the longitudinal way should be paid more attending when analyzed the tomato skining since it would check foremost during warming or mechanical force.

Ho, L.C. , Hewitt, J.D. , 1986. Fruit development. In: Atherton, J.G. , Rudich, J. ( Eds. ) , The

Tomato Crop: A Scientific Basis for Improvement. Chapman and Hall, London,

New York.

Hershko, V. , Rabinowitch, H. D. , Nussinovitch, A. , 1994. Tensile features of ripe

tomato tegument. Lebensm. Wiss. Technol. 27, 86-389.

Dynamic mechanical analysis ( DMA ) , which would supply the dynamic response information of the sample to the alteration of temperature or frequence, has been widely used in the finding of the stuff belongingss ( Zhou et al. 2009 ) . It could provide utile information about the mechanical nature of the stuff, such as storage modulus, loss modulus, and the glass passage temperature ( Li et al. , 2010 ) . The mechanical response of the tomato Peel tested by DMA during warming could good exemplify the existent changing position of the tomato Peel in infrared warming procedure. The frequence expanse could assist to understand the tomato Peel response to different mechanical status like skining or the undermentioned transit. DMA? ? ? 2-3

Jackman has utilized dynamic oscillation techniques to measure the oscillatory strain and viscoelastic parametric quantities of excised tomato phonograph record in order to find the effects of turgor force per unit area and chilling on construction and failure mechanisms ( Jackman et al. , 1992 ; Jackman and Stanley, 1992 ; Jackman et al. , in imperativeness ) .

The dynamic mechanical dad

Tomato Peels have besides been found to exhibited marked viscoelastic belongingss and strain-hardening behaviour ( Matas et al. , 2004 ) . A simple rheological theoretical account for the tomato fruit wall has been proposed, and the consequences indicated that the outer fruit wall and the CM of Inbred 10 and Sweet 100 cherry tomatoes are isotropous, viscoelastic, and, to different grades, strain-hardening constructions.

Matas, A. J. , Cobb, E. D. , Bartsch, J. A. , Paolillo, D. J. , & A ; Niklas, K. J. 2004. Biomechanics and Anotomy of Lycopersicon Esculentum Fruit Peels and Enzyme-treated Samples. American Journal of Botany, 91 ( 3 ) , 352-360.

Zhou, Y.-g. , Wang, L.-j. , Li, D. , Yan, P.-y. , Li, Y. , Shi, J. , Chen, X. D. , & A ; Mao, Z.-h. ( 2009 ) . Consequence of saccharose on dynamic mechanical features of corn and murphy amylum movies. Carbohydrate Polymers, 76 ( 2 ) , 239-243.

Li, X.-Y. , Wang, Y. , & A ; Li, D. ( 2009 ) . Effectss of linseed gum add-on and drying conditions on creep-recovery belongingss and H2O vapour transmittal rate of starch-based movies. International Journal of Food Engineering, 5 ( 4 ) , article No. 10.

To the best of our cognition, there is no survey on the dynamic mechanical belongingss of tomato as affected by infrared warming. Thus this survey would concentrate on the mechanical belongingss of tomato in different infrared warming clip. Four proving manners ( inactive force, weirdo, temperature incline, and frequence expanse ) were used to near to look into the alterations of tomato tegument during infrared desquamation. This survey would supply utile information for the apprehension of the mechanism of tomato infrared desquamation. Besides, it could besides assist to numerically measure the infrared Peel public presentation therefore to optimise the procedure.

2. Materials and methods

2.1 Materials

The XXXX assortment Roma tomato was collected in the local farm ( Woodland, California, US ) . The tomatoes used in this survey were chosen as the medium size, which have weight of 83A±16, volume of 88A±17 milliliter, and soluble content of 4.9A±0.2. Sodium hydrated oxide at analytical class was purchased from Sigma ( St. Louis, US ) . Deionized H2O was used in the full survey.

2.2 IR warming

The IR warming equipment was described in item in old survey ( ) . The tomato was heated between two natural gas-powered IR radiator home bases at changeless power rate for 30s, 45s, 60s or 75s, severally. And so the tomato Peel was carefully removed from the sample utilizing blade. The flesh was removed every bit much as possible from the Peel. Fresh tomato without IR warming was used as mention.

2.3 Dynamic Mechanical Analysis

Two groups of samples were analyzed for dynamic mechanical belongingss utilizing a DMA 8000 ( PerkinElmer, Waltham, Massachusetts, US ) . First group was the IR treated one as described in subdivision 2.2. The 2nd group was peel cut longitudinally from fresh tomato to be used as control sample.

The tomato Peel sample was prepared with four rectangular razor blades mounted on a wood block to acquire approximative dimension of 9mm*5mm*0.1mm. The accurate dimension of each sample was measured utilizing an electric calliper and input the DMA package to minimise the affect of dimension difference on the consequence. Trials were conducted instantly after the tegument samples were cut from the fruit. If failure developed at or near the clamping clasps of the level strip or the round disc samples, the trial was aborted and its informations were discarded.

The movie tenseness geometry was used for both groups of samples. Four proving manners were chosen for the trial: inactive force, creep-recovery, frequence expanse, and temperature incline. In the inactive force trial, an increasing inactive force was applied to the sample with rate of 0.2 N/min. The maximal force applied was 3 N. The applied force and matching supplanting of the sample were recorded during the experiment. In the creep-recovery trial, the sample was equilibrated for 1 minute. Then a inactive force of 0.3 N was applied to the sample and held for 2 min, after which the force was removed and the sample was allowed to retrieve for another 2 min. In the frequence expanse, the sample was tested in the frequence scope of 0.01-10 Hz with changeless preload supplanting of 0.05 millimeter. Ten informations points were recorded for every frequence decennary. In the temperature incline, the sample was heated from room temperature to 120 a-¦C at heating rate of 5 a-¦C/min with changeless preload supplanting of 0.05 millimeter. The frequence was kept at 1 Hz during the temperature incline trials.

Plastic saving movie was used to cover the sample surface to forbid the H2O vaporization in the inactive force, the creep-recovery, and the frequence expanse trials, while Aluminum foil was used in the temperature ramp trial. The inactive force, the creep-recovery, and the frequence expanse trials were all conducted at 25 a-¦C

2.4 Statistical analysis

All the mechanical measurings were carried out at least in triplicate. The experimental informations were obtained straight from the PerkinElmer package V 5.4.7 e??a»¶a??c§°c‰???¬ ( PerkinElmer, Waltham, Massachusetts, US ) . The norm of the three tallies was reported as the measured value with standard divergence.

Duncan ‘s multiple comparing trials were conducted to find the important consequence of IR heating on the mechanical belongingss of tomato Peel samples at P & lt ; 0.05 utilizing the SAS package ( SAS Institute Inc. , Cary, NC, USA ) . The weirdo information was modeled harmonizing to Berger ‘s theoretical account, utilizing the non-linear arrested development characteristic in SPSS 13.0 ( SPSS Inc. , Chicago, USA ) .

3. Consequences and treatment

3.1 Inactive force trial

Inactive force

?‹‰?-­cs„aS›a?”e??a??a??

e‡?a¤?a??a¤s?¬? , e?ˆe¦?

a?Se??e????Ze?™?ˆ?cs„??…a†µa?‹variancea??a¤§a?Y????­?a??cs„??…a†µi??a°¤a…¶???a??longitudinal?-?a?‘

( Hershko

et al. , 1994 ) .

Hershko, V. , Rabinowitch, H.D. , Nussinovitch, A. , 1994. Tensile features of ripe

tomato tegument. Lebensm. Wiss. Technol. 27, 86-389.

e?™c?‡?-‡c« e?????a?‘cs„aS›a¤§a?Zc?µa?‘cs„i??e·Ye§‚a?Ycs„c»“?z?i??e?‚c-•?ˆ»???c?µa?‘i?‰a?ˆe‡?aˆ‚?Z?e®?e”™a?†a?§i?Ya?”e?????e?‚c??a¤sa?????a?‘?‰?e??a?-a?°?­¤c»“?z?aˆ‚

a?”aS›a?”a???›?c??cs„power law?-?c?‹i??Ke??c¤?e«?a?¦i??e?????longitudinala°?i??na»?e???-?cZ‡i??a??a?-e¶‹aS?a??e?‡???

e?™a?›??‘e??a??e??a•Si??i??i??

eˆ?e™‘a?ˆa?‹???a»?e?™a??a?spower law?-?c?‹i?Yi?Yi?Yi?Yi?Y

a…??SSa?”aS›??????stressi??a†??SSdisplacement??????a?”a??i??c„¶a?Z?SSa?”aS›a?”a???›?c??a?s???a???•°i??a??a?-a‰?a?ˆa°??®µaˆ‚

e?™? ·Ka°±???stiffnesscs„a?ˆa??c¤??„?aˆ?

Fig. 1 a?ˆa??c?±?¶??µ“a?¦cs„a›?i??

Fig. 2 a?ˆa???µ?????-¶e-?cs„a›?

a…?a?Zstiffnesscs„???e?°

This initial, additive part of the curve, up to the inflexion, is known as Hooke ‘s part, and it represents

non-destructive elastic distortion that reflects the elastic

modulus ; it is frequently used by stuffs applied scientists as an index of stiffness

of the sample. The incline, K, of Hooke ‘s part represents the

stiffness of the tissue. With the Y-axis stand foring burden and the

X-axis stand foring extension, the steeper the incline, the stiffer the

tissue.

The incline of the additive part of the curve, up to the inflexion

point ( greatest incline in Fig. 2 ) , represents non-destructive elastic

distortion that reflects the elastic modulus, and is frequently used by

stuffs applied scientists as an index of stiffness of the sample.

?‰ˆ??‰cs„e??a?s?-?cZ‡i??c„¶a?Za?-??ˆa¤§aˆ?aˆ‚

Biomechanical features of tomato fruit Peels

stiffnessa?”e??eˆ‰?‹©c???ˆ§?®µcs„?-?cZ‡i??e????‰a????ˆa¤§?-?cZ‡i?Y

The beginning value is used for automatic beginning

output computation ; it is besides known as the cogent evidence strength point, and

is specified as a fraction of the sample gage length that is used to

turn up the 1 % proof-stress point.

e?™a??offset?ˆZa??c?®a®si?Ya?Z? ‡a‡†c›?c??a??c¦»5 % i?Ye‚?e?™???? ‡a‡†c›?c??a¦‚a?•c?®a®si?Y

3.2 Creep trial

Fig. 4 a?ˆa??creep recoverycs„aZYa§‹a›?i??a?†a?¤a??a?±a“?i?sIR skining ?-¶e-?a»?a?S??©a?¦

Creep trial and weirdo curve patterning have been used to the tomato cuticle and cuticle in old surveies ( Petracek & A ; Bukovac, 1995 ; Thompson, 2001 ) . The creep trial consequences of the IR heated tomato Peels were shown in Fig. 4. When the inactive force was applied at the beginning of the trial, there was an tremendous in the supplanting during the first 10 seconds. After that, the supplanting of the tomato Peel would go on to increase at a comparatively low velocity till the terminal of the experiment. But the IR treated samples with different warming clip did n’t demo important difference comparing with the control sample.

Petracek, P. D. & A ; Bukovac, M. J. , ( 1995 ) . Rheologic Properties of Enzymatically lsolated Tomato Fruit Cuticle, Plant Physiology, 109, 675-679.

Thompson, D. S. , ( 2001 ) . Extensiometric finding of the rheological belongingss of the cuticle of turning tomato fruit. Journal of Experimental Botany, 52 ( 359 ) , 1291-1301.

Creep behaviour of tomato Peel can be described utilizing Burger ‘s theoretical account ( Chuang & A ; Yeh, 2006 ) i??which is a four component theoretical account dwelling of springs and dashpots in the signifier of Maxwell and Kelvin constituents. The entire strain Iµ is given by the undermentioned look:

( 5 )

Where E1 ( Pa ) is the instantaneous elastic modulus ; E2 ( Pa ) is the retarded elastic modulus ; I·1 ( Pa s ) is the coefficient of viscousness associated with viscousness flow ; t2 ( s ) is the relaxation clip and I? ( Pa ) is the invariably applied compressive emphasis. The parametric quantities ?•1, ?•2, I·1, and t2 can be obtained from suiting the experimental information to the equation with SPSS package.

Chuang, G. C. C. , & A ; Yeh, A. I. ( 2006 ) . Rheologic features and texture properties of gluey rice bars ( mochi ) . Journal of Food Engineering, 74, 314-323.

Table 1 Burger ‘s theoretical account parametric quantities of the creep curves of IR heated tomato Peels.

aˆˆ

E2 ( Pa )

t2 ( s )

I·1 ( kPaaˆ?s )

R2

control

162.6A±30.2

5.19A±0.89

191.5A±59.9

0.999

30

187.2A±59.6

7.19A±2.84

288.1A±283.3

0.991

45

189.8A±51.2

6.53A±1.38

203A±124.8

0.998

60

198.4A±61.2

6.09A±1.84

142A±43.1

0.998

75

177.7A±54.5

7.29A±2.94

212.8A±91.8

0.991

a…????e°???”controla¤§e°???”controla°? , a?‰a??a?‚?•°a?†a?«e??.c„¶a?Za?†a?«e??a?„a??a?‚?•°cs„a?«a?‰ , a?•c”?a?ˆa?‹.a????”??‰a?ˆa???-‡c?®a?­c”?a?†c®ˆa?-cs„???az‹ , ??‘??”a»-a¤sa?†a?¤a??a…?a»¶ .

Parameters for the Berger ‘s theoretical account of tomato Peels in the creep trial are listed in Table 1. The experimental informations fitted Berger ‘s theoretical account good ( R2 & gt ; 0.99 ) .The E1 value was non shown in the tabular array because the instant elastic distortion was barely detected in the creep curves of tomato Peel. The E2 value is the symbol of retarded elastic distortion, reflecting the opposition caused by the 3D construction alteration of the tomato Peels ( Wang et al. , 2009 ) . All the IR heated samples have higher E2 value than the control sample, bespeaking that the IR warming could increase the sample ‘s opposition to long-run distortion. The E2 value of the tomato Peels have been found to be increasing with the temperature addition in old survey ( Lopez-Casado et al. , 2010 ) . The relaxation clip, t2, is the clip required for the applied emphasis to diminish to 1/e ( about 36.8 % ) of its initial value under changeless distortion ( Jimenez-Avalos et al. , 2005 ) . All the IR heated samples have somewhat higher t2 value than the control, but have no important difference between each other ( p & gt ; 0.05 ) . The I·1 value is the contemplation of the viscousness of the samples, which did n’t demo important difference between the IR treated samples and the control, as shown in Table 1. The mold of the weirdo curves has been used on the tomato cuticle in old survey, in which comparable but lower E2 values and higher t2 values have been reported ( Lopez-Casado et al. , 2010 ) .

Jimenez-Avalos, H. A. , Ramos-Ramirez, E. G. , & A ; Salazar-Montoya, J. A. ( 2005 ) . Viscoelastic word picture of gum Arabic and maize amylum mixture utilizing the Maxwell theoretical account. Carbohydrate Polymers, 62, 11-18.

Wang, Y. , Wang, L. J. , Li, D. , Xue, J. , & A ; Mao, Z. H. ( 2009 ) . Effectss of drying methods on rheological belongingss of linseed gum. Carbohydrate Polymers, 78 ( 2 ) , 213-219.

BIOMECHANICS AND ANATOMY OF

LYCOPERSICON ESCULENTUM FRUIT PEELS AND

ENZYME-TREATED SAMPLES1

ANTONIO J. MATAS,2 EDWARD D. COBB,3 JAMES A. BARTSCH,4

a?Ya?sa?†creepi??eˆ?a?”?SSa¤s?¬?creepcs„a›?c‰‡?”?a?Sa?†

?SScreep?•°??®a?-a???•° , a?‹a?Za?sc???ˆ§?-?c?‹ , ?-?cZ‡a??a??rate of weirdo.

e?™a?›a??a?‘cZ° , a»Zrate of creep???c?‹ , skin a’?CMa?‹e-??????‰a¤?a¤§a??a??.a?†???aS›a»Za°?a?°a¤§a?Za»Za¤§a?°a°?a?‹e-?a??a?«??Z??? .

e?™c?‡?-‡c« a?­creepa??cZ?c”?a?†eˆ????a?zaS cs„aS› , a?¶e®?c®-young ‘s moduluses?c?ˆaS›a?zaS eˆ?a?zaS , e?™e????Ze??c???Y?cs®cs„????-™c‰??ˆ§???a?- ” a?”aS›aZ†a?? ” a?±a“?cs„aˆ‚a?†????­¤?-‡a???-¶eˆ?e™‘a?†a?¤a??a› c? i??a?ˆa????? ” a?”aS›aZ†a?? ” aˆ?a?ˆa?????aS›cs„a?za¤§i??eˆ???‘cs„a®ze??a??a»?e????Zi??a?”aS›aZ†a??e‚?a®s??‰a?±a“?aˆ‚a??a?Za?ˆa??????-™???e??i?????e‡?Ea??a?”e??a??a?-i??a¦‚?z?a®ze??a¤Yc??c?®aˆ‚

a®??•?cs®cs„young ‘s modulusa??5-25MPa, CMcs„a??10-60MPaa?‹e-? , a?Z??¬?-‡c›?c¬¦a??

e?™c§????az‹cs„?-???•a??a?‹e??e?™c?‡?-‡c« e‡?e??a?Y??‰c”?a?° , a»-a»¬c”?

LTEa’?KE1e??c¤?short-term weirdo, c”?KE2a’?VFEe??c¤?medium to long-run behavior

Log-time map component, Kelvin component, syrupy flow component

e?????Rheological modelcs„a?ˆc§?i???‹????a‡‘cs„i??e·Y??‘c”?cs„???az‹??‰c‚?a??

EXTENSIONMATRICaˆ¦ e?™a?ˆc?‡

e?™a??a›?e????Za?»e¦??‰?a?-aS›cs„e??a?†???cuticle, a…¶a»-cs„c»†e?za¤sc‚?a°‘c‚??- ?‰ˆe°“

3.3 Temperature incline of the tomato Peels

Fig. 4. Effectss of infrared intervention on the storage modulus ( E ‘ ) and loss modulus ( E ” ) with response to the increasing temperature ( the labels with figure shows the intervention clip ) .

The mechanical response of tomato Peels to the increasing temperature as affected by infrared warming was shown in Fig. 4. The storage modulus values of all the samples foremost decreased with the addition of temperature ( see Fig. 4A ) , so started to increase after reached their lowest point ( named as “ passage point ” in this survey ) around 60-80 a-¦C depending on the intervention clip. This tendency was consistent with old survey in which the storage modulus of tomato Peels was found to get down diminishing about 20 a-¦C ( Matas et al. , 2005 ; Lopez-Casado et al. , 2007 ) . However, no passage point was reported in the above survey due to the temperature bound ( up to 45 a-¦C ) and deficiency of informations ( merely 5 informations for the whole temperature scope ) ( Lopez-Casado et al. , 2010 ) . As shown in Fig. 4, all the IR treated samples have both higher storage modulus value and higher loss modulus value than the control sample. The loss modulus was found to hold similar tendency with the storage modulus ( see Fig. 4B ) , in which the loss modulus foremost diminishing so started to increase when the temperature was increasing. Passage point was besides found in the temperature curve of loss modulus. But it was non discussed in item because of it was extremely coefficient with the passage temperature of loss modulus.

Matas, A. J. , Lopez-Casado, G. , Cuartero, J. , & A ; Heredia, A. 2005. Relative Humidity and Temperature Modify the Mechanical Properties of Isolated Tomato Fruit Cuticles. American Journal of Botany, 92 ( 3 ) , 462-468.

Lopez-Casado, G. , Salamanca, A. , & A ; Heredia, A. 2010. Viscoelastic nature of stray tomato ( Solanum Lycopersicon ) fruit cuticles: a mathematical theoretical account. Physiologia Plantarum, 140, 79-88.

Lopez-Casado, G. , Matas, A. J. , Dominguez, E. , Cuartero, J. , & A ; Heredia, A. 2007. Biomechanics of Isolated Tomato ( Solanum lycopersicum L. ) Fruit Cuticles: the Role of the Cutin Matrix and Polysaccharides. Journal of Experimental Botany, 58 ( 14 ) , 3875-3883.

Fig. 5. Effectss of infrared intervention on the passage point of the tomato Peels during temperature incline ( a. Passage temperature ; b. Modulus value at passage point ; c. Tan delta value at passage point ) 1.

1 Valuess of each saloon with different labels were significantly different ( p & lt ; 0.05 ) .

The mechanical information of the tomato Peels treated by infrared warming at the passage point was analyzed and illustrated in Fig. 3. The passage temperature of all the treated samples are significantly lower than the control sample, which bespeaking that the tomato Peels are traveling to acquire their mechanical failure at lower temperature. This could be a symbol for easy skining during the tomato processing in nutrient industry, where the tomato was foremost heated before skining. All the IR treated samples shown similar passage temperatures between each other as indicated by Duncan trial ( shown in Fig. 5a ) . It reflects that even a short clip IR intervention could accomplish low passage temperature of the tomato Peel.

All the samples have comparable but lower modulus value with old surveies on tomato epidermal membrane. It make sense because epidermal membrane is a thin bed but provide the chief mechanical support for the Peel, therefore doing it has higher modulus values based on the computation ( Allende et al. , 2004 ; Matas et al. , 2005 ) . Both of the storage modulus and loss modulus values of infrared treated samples are significantly higher than that of the control samples, as shown in Fig. 5b. This difference in modulus indicated that IR treated tomato would probably to stay larger Peels and less clefts during the desquamation procedure. It is because the high mechanical strength of the IR treated sample could assist to keep the Peel from checking. e?™a??a?°?-?e??a·®a?ˆa??deltacs„???e?°

Allende, A. , Desmet, M. , Vanstreels, E. , Verlinden, B. E. & A ; NicolaA? , B. M. 2004. Micromechanical and geometrical belongingss of tomato tegument related to differences in puncture hurt susceptibleness. Postharvest Biology and Technology, 34, 131-141.

3.4 Frequency expanse of the tomato Peels

Fig. 6. Frequency spectra for the storage modulus and loss modulus of tomato Peels treated by IR warming ( a for storage modulus ; B for loss modulus ; degree Celsius for tan delta ) . The solid lines in the figure a and B are the tendency lines of the Power Law theoretical account.

The frequence response of the modulus of tomato Peels as affected by the IR intervention was shown in Fig. 6. All the modulus values of the samples were increased with the addition of frequence, bespeaking the viscoelastic nature of tomato Peels. And the modulus values of IR treated samples were all higher than the control sample. This sort of modulus difference was besides similar with that in the temperature incline trials. A possible ground is that the IR intervention could cut down the wet content of the tomato Peels, particularly the surface epidermal parts. And the epidermal membranes, which was chiefly made up of pectin, was the portion contribute most to the mechanical strength of the tomato Peel. And so the modulus values were increased, because the wet content was found to be negative for the mechanical strength of tomato Peels ( Lopez-Casado et al. , 2007 ) .

Lopez-Casado, G. , Matas, A. J. , Dominguez, E. , Cuartero, J. , & A ; Heredia, A. 2007. Biomechanics of Isolated Tomato ( Solanum lycopersicum L. ) Fruit Cuticles: the Role of the Cutin Matrix and Polysaccharides. Journal of Experimental Botany, 58 ( 14 ) , 3875-3883.

The frequence dependance of storage modulus ( besides called elastic modulus ) E ‘ and loss modulus ( besides called syrupy modulus ) Tocopherol ” for tomato Peels can be about described, for the frequence scope studied, by the Power Law theoretical account ( Ikeda & A ; Nishinari, 2001 ) :

( 3 )

( 4 )

where K ‘ and K ” are invariables and N ‘ and Ns ” may be referred to as the frequence advocates, and I‰ is the frequence. The value of N ‘ and Ns ” can supply utile information sing the viscoelastic nature of nutrient stuffs ( A-zkan et al. , 2002 ) .

Ikeda, S. , & A ; Nishinari, K. 2001. On solid-like rheological behaviours of ball-shaped protein solutions. Food Hydrocolloids, 15, 401-406.

A-zkan, N. , Xin, H. , & A ; Chen, X. D. 2002. Application of a deepness feeling indenture hardness trial to measure the mechanical belongingss of nutrient stuffs. Journal of Food Science, 65, 1814-1820.

The Power Law parametric quantities of the frequence spectra of tomato Peels treated by infrared warming were shown in Table 1. These consequences could be used to accurately depict the effects of IR or lye intervention on the frequence response of the modulus. The K ‘ and K ” values could be used as standard values for the overall modulus scope. And the N ‘ and n ” values could reflect the degree that how much the modulus of tomato Peels would be affected by the addition of frequence. Because of the complexness of the tomato Peel construction, there is normally a well large fluctuation in the mechanical analysis of tomato Peel ( Hetzroni et al. , 2011 ) . But the Power Law mold could enable the look of the alterations caused by IR intervention in footings of basic mechanical parametric quantities, which are least affected by the type of instrument method ( Hershko et al. , 1994 ) . As shown in Table 1, the K ‘ and K ” values are steadily increased along with the addition of heating clip. The 30s samples are somewhat higher than the control in K ‘ and K ” values. But the 45s, 60s, and 75s samples are significantly higher than the control and have no important difference between each other in K ‘ and K ” values ( P & lt ; 0.05 ) . It means that the 45s infrared warming was plenty to dry the epidermal membranes to certain distance so that the storage and loss modulus would be higher than the control. The K ‘ and K ” values of the treated sample are more than two times as the control 1s. No important difference is found between the control and treated samples in N ‘ and n ” values.

Since the mechanical features of the tomato Peels were strengthened by the infrared warming as indicated by the temperature incline and frequence expanse consequences, the mechanism of the infrared desquamation would less likely to be because of the construction destroy of the Peel caused by heating. In general, the applying of IR warming could increase the mechanical parametric quantities of the tomato Peel so that the Peel would stay in big piece to assist the Peel aggregation procedure following warming and desquamation. The larger piece of Peel has besides been observed in the practical use when comparing the infrared warming and the common lye skining methods ( informations non shown ) . Thus the mechanism behind IR skining would more likely be the relaxation of the connexion between the epidermal membrane and the out bed of flesh, which still need future verification.

Hetzroni, A. , Vana, A. , & A ; Mizrach, A. 2011. Biomechanical features of tomato fruit Peels. Postharvest Biology and Technology, 59, 80-84.

Hershko, V. , Rabinowitch, H. D. , & A ; Nussinovitch, A. 1994. Tensil Characteristics of Ripe Tomato Skin. LWT- Food Science and Technology. 27, 386-389.

Table 1. Power Law parametric quantities for the frequence spectra of tomato Peels treated by IR warming.

Heating clip

K1 ( MPa )

n1

R2

K2 ( MPa )

n2

R2

control

30.1A±10.4b

0.077A±0.001a

0.92

8.6A±1.63b

0.104A±0.007a

0.97

30

48.2A±20.9a, B

0.08A±0.002a

0.90

13.9A±7.9a, B

0.126A±0.011a

0.93

45

71.4A±12.4a

0.078A±0.012a

0.97

18.8A±3.21a

0.092A±0.018a

0.96

60

75.1A±21.7a

0.095A±0.019a

0.99

20.6A±0.88a

0.144A±0.01a

0.98

75

74.3A±14.9a

0.08A±0.039a

0.94

20.1A±1.96a

0.107A±0.068a

0.75

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Postharvest Biology and Technology 59 ( 2011 ) 80-84

Biomechanical features of tomato fruit Peels

Amots Hetzroni, Arie Vana, Amos Mizrach

Matas, A. J. , Cobb, E. D. , Bartsch, J. A. , Paolillo, D. J. , & A ; Niklas, K. J. 2004. Biomechanics and Anotomy of Lycopersicon Esculentum Fruit Peels and Enzyme-treated Samples. American Journal of Botany, 91 ( 3 ) , 352-360.

Cuticular membranes??”peel?›?a??a¤§cs„a?¦a?ˆa??e????®i??a??? ·c”????e§?e‡Slyea‡?a°?

Pectincs„a??c”?aˆ‚e?™c?‡a°±???e…¶a¤„c?†cs„?-‡c« i??

e?™a??c‰??ˆ§e·Ye??c???Y????a?¦?•??„Y?ˆ§ susceptibleness to checking when ripe

e??cs®a?»e¦???‰a?¤e??a?†c»„???i??CPa’?CLi??c»„???CMi??a…¶a?­CLa?»e¦????a?†???pectin-rich part

eˆ?e?™a±‚pectina??e?????a?»e¦?cs„tensileaS›e‡???????

a????”c”?e…¶a¤„c?†cs„i??a??a????”ira¤„c?†cs„

Peel?????”CM?›?a¤§cs„?¦‚a?µ , CMa?????e??a±‚

?‰ˆe°“cs„strain hardencZ°e±? , ??‰a??a›?c‰‡c¤??„? , a°±???c»†e?ze?«?‹‰e•?a?†

We believe that strain-hardening and strain-softening reflects

the response of microfibrils in the CM to tensile forces.

Prior work indicates that fibrillar constituents in cell walls can

increasingly align in the way of applied tensile forces

such that the effectual Young ‘s modulus additions ( see KoA?hler

and Spatz, 2002 ) .

However, when overly extended, the

filaments may steal past one another ( as their matrix deforms ) and

the Young ‘s modulus lessenings.

KOA? HLER, L. , AND H.-C. SPATZ. 2002. Micromechanics of works tissues beyond

the linear-elastic scope. Planta 215: 33-40.

Harmonizing to this theoretical account, a tensile force causes cell wall filaments to progressively aline analogue to the way of the applied force, thereby increasing the CM Young ‘s modulus

( strain-hardening ) . When overly extended, fibrils Begin to

faux pas past one another diminishing the CM Young ‘s modulus

( strain-softening ) . The magnitude of the ”critical ” force will

depend on the original net orientation and copiousness of CM

filaments, which will correlate to some grade with the thickness

of the CM.

Lopez-Casado, G. , Matas, A. J. , Dominguez, E. , Cuartero, J. , & A ; Heredia, A. 2007. Biomechanics of Isolated Tomato ( Solanum lycopersicum L. ) Fruit Cuticles: the Role of the Cutin Matrix and Polysaccharides. Journal of Experimental Botany, 58 ( 14 ) , 3875-3883.

Mechanical behavior of stray tomato fruit cuticles and their cutin matrices

e?™a?¤a??e??e??a??a»?e??a??a??cs„ a??e?? , e??c???Y?cs®cs„e§’e??a±‚ , e®?e®?cs„?-¶aˆ™a??c”?

??©a?¦a?sa?ˆa§‹a?‡e«?cs„?-¶aˆ™ , ???e‡????e™?a?Zcs„ , a??e?™e‡?e?«e??a®z

???a?????c†Ycs„rede??cs„ , a??c”?

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