llnJ SL t li'thnul.R*.l9r1l.5iI :ll.:r)ll

Instrumental Texture Profile Analysis of Date-Tamarind Fruit l,eather u'ith

Dill'erent Types of Hydrocolloids

Karimr Zahir Ar -Hrr.rr. Nejib Gurz-,rrt'. V'andita SIxt;tt- N4ohammad Shaliur Rrrv,rr and Lyutha .At -srnrrt

Dc'purtnur ol t'ood f ietrc,tnJ ^utrition

(oll(E

K ho.l- I :.1. lt ulr\d, Qm.nt

Received Octoher 23. 2012: AcceDted March ,1.201-l

Date-tsmerind fruit leath€rs with varied tertural chsrrcteristics wcrc prcprred bl drying I pisieco[taining h!dmcolloid (srarch, pectin. dextrin or guar gum) and weter et 70"C for Zlt. 4!, 56. 70 snd tlrf

h. Hardness, cobesiveness, adhesiveless. springilless, hrittleness, rcilience, gumminess and chewiness ofthe blsnk date-temsrhd fruit leathcr (Le., without rlly hydrocolloid) did not show sn] correlatioo with

tbe moisture cootena rangcs (29 - 4l !y'I00 g ismple) used iE the present studv. Hardness and gummineis

increas€d trhen hydrocolloids were added, while cohcsiveness, reiilience and springincss decressed. Withthe erceptioD ofderFin all olher hydrocolloids increascd chewiness. Principal Component Altal]sis (PCA)

identifed 5 principal comporents (i.e.,5 fsctors: phsticity. elastici0; hydrocolloids' cooceotlrtioo, resilience, cohesiveness) sffecting thc cherrclerislics of each dst€-tsmfitrd fruit lesther. The cluster rn|lysisidentified 4 classes of the fruii lcgthers Nnd biplot (i.e., including all products and tieir characteristics),gcnerated through l'CA, recognizcd these clrsscs ss hard-chet1; soft-spring\ hard-fragile and sofi-resil-

irnl lesthcrs.

Kcvwords: texture. lhril-lealher. hldJocolbids, cluster analysis. principal conrpolcn! aDallsis

lstrodu ction

Fruit leather refers to fruit rolls or fruit roll-uDs which is

a confectionery product rnade by dehydraring tilit pulp into

leathery sheets with chewy texture with difl'erent degrees

of hardness (Hardeep and Satinderpal. 2003; Andress er al.1999). Fruil lcathers are examplcs of hcalth food snack duc

to thcir narural ingedienrs and nutritiqnal contents (Raab

and Oehler, 1976). Five main steps are needed in the procsss

of the fruit leather. These include cooking, spreading the

puree, drying, pouching and packaging. More details of the

differcnt alt€m8tivc steps arc provided by Mjayanand er al(2000). Maskan er al (2002) and Nas and Nas (1987). Three

primary ingrediens are usually used to manufacture fruil

leathers. These are: (i) fruit pure€, (ii) food additives and

(iii) swecreners. Fruits like chiku, jackfruit, and apple have

been popularly used in preparing fruil leathers (Hardecp and

Salinderpal. 2003). Sweeteners gencrally include com syrup

or sugar such as sucrosc, glucose and fruclose. and in some

rTo whom conespondence should be addressed.

E-mail: guizani@squ.edu.orn

products. include both. Various additives may be adde.d to rhe

msrufacturcd fiuit leathers; they include panially hy&ogc-

natfd cottonse€d oil. glycerin or diglyceride. hydrocolloids,

anificial and ualural colors and flavors. and added acids

such as acctic and citric acid. Hydrocolloids are imporonl in

maintaining desired texrure ofthrit leathers. They have b€en

used as gelling or thickening agcnc capable ofbinding water

molecules, thereby enhancing the desircd l€xtural prope es

of foodstuffs (Rasc6n-Diaz et al., 2012)

lnstrumental textunl characteristics of fruit leather ate

measured ro match with the dcsired cbaracteristics wbeo

diffcrcnt typ€s of hydrocolloids arc us€d (Cujral a|ld Brar,

2003). Instrumcntal Textute Profile Analysis showed that

high *ater content increased cohesiveness and decreased

springiness of pear fruit leather (Huang and Hsieh, 2005:

ChcMan and Tauhk, 1995). Hardncss ofmango and guava

leathers decreased with thc increas€ of moisturc content

(Vijayanand et ol..zotJo\. Puncture force of mango leather

decreased witb lhe increase in water conlent due lo water

absorption during storage (Azercdo ct,r/., 2006). It rvas

observed that using higher pectin contenl rcsulted in higher

5tl

hardness. cohesivcncss. springincss. antl che*incss ol pcar

fruit lcathcr; horvevcr thc addition ef com s)'rup caused soli-

cning of thc fruit lcathcni (lJuang irnd Hsich. 2005). Instru-

ment;rl hardncss and rcsilicucc of papay-a-tomalo tiuil lc'ather

(75:f5 ratio) showed that highcr lcvel of pectin and starch

conccntration (i.e., in conrbination) incrcascd hardness,

uhile rcsilience did not show any trcnd of papaya-tomato

liuit leather (?5:25 ratio) (Ahmed cr dl. 2('05). Ccllulose

increased hardness more as compared to pcctin in the leather

containing both slarch and cellulose (0.5 and l9i, concentrit-

tion), whcreas starch lowered hardness as compared to cel-

lulose in the leather conraining bo$ pectin and cellulosc or

starch ( l.oyo concentration). The extcnsibiliry and encrgy ro

rupturc for maogo lcather decrcascd with incrcasing levels

of soy protein conceDraE. skim milk powder and sucrose

(Gujral and Khanna, 2002). Tensile srength incrcssed con-

siderably wirh increasing pcctin content and thc same was

truc tbr incrcasing glucosc syrup conlent in kiwi fiuit lcathcr

(Vatdnnakul et al..20l0l, and su-dwbcrr)' fruit leather (Rar-

phitagsanti,2004l.

Dates, thc fruit of thc d*e plm Phoenix dauT-liferea, atcone of thc important agricultural commodities in the Middle

East rcgion. About 12 diffcrcnt varieties of dates arc Itownin Omarl aad thcy clnstitute a significanr source ofnuriensfor $e inhabitants (Kasapis er al, 2000). Among thc l2 vari-

eties, five are commercially imponant and the remaining are

low in value duc to their lo*'sensory charactcristics. ln this

case. fruil leather could be developed by utilizing the lo*value fruits and this could provide economic gain and reducc

thc t'ood wasE. Healthy sDacks, such as date tamarind fruitleathcrs could be developed by utilizing locall,'.' available

datc &uit and this could provide a valuc addirion to the low

value dates. The use of umarind in cornbination with dstes

could add a sour flavor to lhe lcadrcr and balance thc higb

swcetness of datet. ln addition lamarind, high in polysac-

charides, is known to form suble gels over a wide pH rangc,

thus less sugar is needed lo achieve I desired strength thart

in conespondiog pcclin gcls (Belitz and Grosh. 1999). Most

of the rcscarchcs on fruit lcathers wcre conduclcd using

papala mango, orange and bamna as rar! material. Scanty

rescarch has been reportcd using date-tama nd formula-

tion fruit leather. The objecrivc ofthis study tlas to dcvelop

dale-iamarind fruit lcathcr with different q'pes and levols ofhydrocolloids: and to measure its hardness. cohesivcness.

adhesiveness, springiness. brittleness, rcsiliencc. gumminess

and chewiness by instrumental texture profile analysis (TPA).

The results obtained \rere comDared to lhe textuml charactcr-

istics of two commcrcial types of fruit-lcatlcrs (hard-clre*y

and son-springy) purchased from thc local market.

K.l Ai.'tll\\, r,.rl

iUrtcrials and iUrthods

Soutt't's r{ nucrtuls Onc balch ol dates 1A'/rolar r art-

eties. f,/,,lr stlgc nraturitl ) anJ <ie-pittcd tamarind (lndtan.

Royal brar)d)rrcre purchlscd liom a local supcrnlarket in

Muscnt. Sullamtc ol'Oman. and samoles wcre slorcd at roon

tempcraturc until used lbr the prcparation ol' fruit leathers.

Diffcrent hydrocolloids. pectin (P: apple 250 grade, BDH

Biochenrical. England). starch {S: corn. SIGMA-Aldrich

Chemical Company, Steinhcim. Cermany), mahodextrinc (D:

SIGMA-,Aldrich Chemie Gmbh, Cermany) and gu$r gum (G:

Aldrich Chemical Compan)-. lvlilwaukcc. USA) were used in

the prepar-ation of date-Emarind lruit leathers. Date-tamannd

lcatler without any hydrocolloid was used as blank (B).

Prcparation of datelamarind teqrhcr Onc hundred

gram de-pitted d8te fruit flesh and 100 g tamarind were

plsced i! a metal pot and mashed with hand held masher

After mashing. 200 g of *a!er was sdded to the mixturc. H-v"-

drocolloids (surch, pectin. maltodextr;r\ End guar gum) were

add€d at difltrcnl amounE to make thc final concelrations

ar l,2, and 3 9,100 g purce (based on total mass ofdale.

lamarind. 8sd warer). All purces werc rhoroughly mixed in a

blendcr Philips. Cucina) ar room tenperature (i.c., 20'C) jbr

l0 min in order ro form smooth puree. In the crse of starch,

200 g of watlr was mixed with s|sr€h ( 1.5. 3 or 4.5 g) and

heated at 80"C for l0 min on a hot plate to allow clmplet€

gelatinizadon and then mixed with mashed datc and tama-

rind. lt has becn reported in $e lirenturc that h€ating 8t li0'C

for l5 min was cnough to completcly gclatinize \'!'ax\ starch

(Maurice eral.. 1985). Thc moisture content ofthe purce was

determined by oven drying ofaround 5 g purec at 105"C ,br

d lesst 18 h.

Thc prepared date tamarind purcc *'as p<xrrcd on a plastic

wrap placed insid€ a slainless steel dish (diameter l9 cm)

(Cling wrap, GLAD company). The edge ofthe plastic urap

wss cut-olf so that the surface of the puree q,ill be all cx-

posed during drying. Puree (thickness: 2 cm) in 5 dishes were

placed in a cabina drier initirlly set at 70'C. The first dish

r.vas removed from $e drier a$cr 28 h. All remaining dishes

were takcn out at l4 h interv"l aftcr the fint dish. While dry-

ing, the face of thc leather was tumed over every 14 h. The

leathcr Iaken out at cach inlerval was wrappcd with plastic

and placed in a Ziplocl bag to avoid any moisture exchange

until used for TPA. Sample b0gs werc placed in a rcfrigerator

at 4oC until they were used for instrumcntal TPA analysis.

Samples wcrc identificd uith o code consisting of a lcttcr

and a three digits nunrber. Thc firs( letter concsponds to lhc

hydrocolloid namc. thc finil digit indicates lhe concentratr(tr

of thc hydrocolloid lscd in lhe lormulation 5nd thc last r\ao

digis i|ldicatc thc timc ofdrying ofthe datc-tamarind leathet

For example sample P356 means that lhe hydrocolloid rddcd

I PA Profilc ol Dar!-lanralnd Lcathcr

w s p.ctin at a conccntrati(n ol -l g. 100 ! purgc lnd thc dry-rng trmc ofrhc learhcr $as J6 h. Thc blank $as idcntrlicd byrhc lcttcr B l|nd cornnlcrcial ones h1 ( lollor{!d b_\,the lettcr\( i h)r grnpcJ. l\4 lirr rnrngo, 0 lbr rrrangr, an<l S lirr strarvbcr_

ncs,

lnstrumcrtul textvrc roflc analtst\ lTIitl Trvo com_pression-dccompression cycles of instrumental TpA u,as

conducted using a Texrure Analyzer (Model TAXT2, Stable

Microsystems Ltd.. Godalming. Suney. UK1. The textureEnalyzcr was anachcd to thc computer software ..Texture

Ex-pcfl". ln ordcr lo mcasure the instrumental TpA. fruit leath.ers lverc €.Lcn out from the refrigerator previousll,. and kept

at room lempe.ature for about 30 min_ Ihe square shapedleather wls cul into l0 samples of 1.5 x 1.5 cm $,ith a thicl._

ne$ of I cm The sample was thcn placed on rhc centcr ofthc TPA insrument's platform and it was comorcssed rwiccto ?5% ofthe original heighr ar a compression rare of I mry'sat roon bnpcratuF (20.C). The duratior between 6nt and

second comprcssion was 20 s. Thc pre and post-tcsr speed ofcornpression *,as 5 mm/s. A! least l0 rcplicares werc madeibr cach leafter samplc.

The compression-decompression cycles provided a force-timc graph and led to rhe exrraction ofeigbt parametcrs(Figure l): hardncss (H,4.), cohesi!,eness (CO), adhesivcncss(AD). springiness (Sl,), brirtleness or fraclurabiliry (FA),resilicDcc (RE), gumminess (CU) and chewiness (CH) (Rah-

m8n and AI-Farsi. 2005). Hardness (HA) is defised as theforce (N) needed to attain a given deformation, adhesiveness(AD. area A') as the work (N s) needed to overcome thc at-tractive lorce bet\r'een food and placc surface, fracturnbility

Tim€ (3)

t'ig. l. A lypic.l lorce-rime graph of t*.o-cycle inslrunenlal TpAfot date-urnarind leathcr lAr: firs! compaession (Ns); A?: sccondcomprcssion (Ns)t A,: firsr dcmmprcssion (Ns): ,{.: sccond dcco|n-ptcssion (Ns); xt distEDcc froE slart of sccond comDressioo to thePczI (s): ): dislance Forn stai ofs€cond compression (o 0rc pesli (s);.\: fir$ flosilive peak ancr the maximtrm poin. ro base line (Ns)i {:arEs of firsr posirile peak from rhc inniarion lo dtc n.xtmum Frint(Ns)

5,i :j

(fA);rs lirrcc l\) ot'ii)od liacture. rcsilicncc (llh. ralio ol.arcn ot lirsr postlar.r pctl xlicr the tna\rmutn point lo ba\eljnc dividcd b1 the arca ot,irst posilir,c n.a! tiom li!,in{A.lr(D lo lhc nri\rmur ll(,int, .,\, and .\ I !s rhc cuprcit\ !,t'thcsample lo fight bacl to regarn is orrirnar posluon! anc co-hesilcncss (COl. rurio ()1 4. and A,)as rhe inlcmal xrtegrinofthe sample. The gunrminess (GUlj is deiined as rhe mul_tiplication ol'HA and C0l, uhilc che$iness {CHl) as themultiplicarion ofGU I and COl. Chewincss is used for solidsamples and lummincss is uscd for scmisolidj. Horvelcr. thedale-iam3rind lcrthcr samples wcre close lo solids or semi-solids based on thc formularions. thus we have included andanalyzed boti the charscteristics. The cohcsiveness 2 fCO2= (A: - A,)dAr - Ar)l is deterrnin!'d from rhe rario aftcrcxcluding ncgativc ateas for lhe first and sacond dccompres-sions. CU2 is detrncd as the muhiplicadon of HA and CO2.CH? is the multiplic8rion of GUl and COl, CH3 is rhe mul_tiplicstion ofcut aad CO2, and CH4 is the multiplication ofCU2 aod COt, resFcrively. Springioess t (Spt) was definedas thc distancc (x) from srsrt of sccond comprcssion to tlepesk (s), whilc springincss 2 (SP2) is considercd as rhe ralioofthe distanc€ (x,/y) from tbe stsn ofthe secono comDrcssronto ils pesk ard thc dislancc from the stan ofthe 6rsl com_ptession to its pcrak (Rnhnun and Al-Mab.ouqi, 2009).

Statisticol orallsis The srstisricsl significancc cor-rclations of differcnces mcchanical properties with watc,conteDl werc derermi.Ded by PAST softmre (pAleollologicalSTaristics) snd p values were reported. Two multivariatc ex_ploratory methods (i.c., clusteriog and principsl compon€rtanalysis) werc uscd to idc.rtiry overall changc in rc^rurc ofdiffcrcnt rypes of date-kmarind lcarhcr formulations. Bothanalyses wcrc perlbrmed with PAST soil\\'arc (i). For bothCluster Analysis and Principal Componenr Analysis. eachcharscteristic was standardized to rcmove undesired effeatsrclated to thc sizc ofthe mersirrcment by lirst subtracting thcmcan from thc obscrved valucs and then dividing by thc srao-dard dcviation ofthat particular charscrcrislic. A hisrarchicalclustering using Ward's metbod (Ward, 196l) of varianccmilimizstioD *irhin groups was applied ro thc ll charscter.istics measur€d b:/ TPA. Tlre number and thc conrposition ofthe clusters retaincd wcrc estimated by risual observarion.

Results rDd Discusrion

lnstrume sl lexlut" pmfle anal-ysis ffP D8re ta.rna-

rind lealhers werc dri€d for 2E,42,56.70 and E4 h. Tables Iand 2 show the texnrral att ibutes ofdale-tamarind fruit leath-

er with starch aod pectin, Thc moisturc content dccreased

with thc increasc of drying rimc (]?bles I and 2). A typicalplot ofrhe r$,o cycles compression and decompression force

as 8 function of lime is sho*n in Figure l. The positive areas

2- 1loo(,bo

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l.9r l.: OI7.0,01 0.16r0.01 0.08.0.01

J9+ r.l rJ.llno0! 0.lri r 0.0r utor0,0l

:._r:0{ 0.60:u t0 1t:r.l:arl 0i 0.lt!-0.08 3.t,{i.!r.r. rJJ o.Ji:00t :r14-il : ri: 03! ori lrjil).{.l 5 .: 0.t5:0.11 3.s: r 6

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I i J |: 0.lr:0.r1 0 6:0 ir.r,0l o.lJ: uo.l 7.9: I jI -:10 | 0Jli:018 :1.0.0?ll,0: 0.11i0.$ A1:0J1.6:0,J ojt.0.0j {.E I l,lI.l r O: 0-l?.O01 {r0rt I

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lrblc f,. Atlribures ol'drtc-tcmarind il'uil leathcr $,ith Decrin.

l\t. \,, FRI\r ll.lt\r riltrri. !r)lr.r i',: tJl ll'l r,r

Pl:3 {0.t ll.3:{.5 :4Jt 9JPlal l.l: l:..)t 19 l0l+t.6tlJ6 I l.-r al.l*.{.5 4i,0r?.0Pl?0 :?,1 ,0.:i 7-3 8:l-5t ?.1

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'|,01rs.l !_tr t.1

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'.€ : l.: 1.1..1 r 6-! L8 ' O.e

9.{=:.? I26.9!!1.9 E.0r l.i

&: Moi$c 6nd! FR: Fe[,nbilit! O.lt H^ H.dEs (N). AD: Adhai\.@ (Ns). Col: Cohsdlffis I ir. CO:j Coh6itffi.RE: R!"ilicne. SP l: SgitrtiB t lll SP?: SFnSj!.ar:. CUI: (n!nnril.*r | (N). (;Ul: Oumrio.sr 2 {l\ r CHl,lHl CHl.Ctt4: Chcris6 l:J,4

(Ar and AJ ar€ for th€ comprcssion cycles and thc ncgatiw

aress (Ar and Ai) are for tbc dccrmpr$sion cycles, loitialstatistical analysis showed no significant improvcment ofSP? a5 compsrEd ro SPl, GU2 as comparcd to hc GUl, and

CH2, CH3, CH4 as compared to CHI (p < 0.05). Ihus only

original dcfinitions sf SPl, CUl. and CHI were used forfurdrcr analysis- Hardness and gumminess increased with tho

addition of hydrocolloids tphile cohcsiveners, resilience and

springiress decreased, Considering the correlation a$lysis,

hardness and gurminess of date-tamarind leathcr incrcased

with an incrcasc in hydrocolloid corrccntration except for

dextrin. qhich had an oppositc cffccl Hardness was high-

est in date leather containing pectin followed by gusr gum.

starch and least in dextrin. Gumminess was highest in datc-

tanlarind leather containing guar gum followed by frectin.strrch and least in dextrin

Correlalion hel$.een irrgredients and mechonical char-

acteristi.;.s When starch u,as uscd. the nloisrure content

showed significaot coffelation with all mechsnical char-

acterlstics ( i.e., &acturability. hardness. {:ohesi veness, ad-

hcsiveness. spriDgiDess, resiliencc. gumminess atd chewi-

ness), *'hile only chewiness (CHl ) characteristics showcd

conclation wilh conccntidtion of hydrocolioids ip . 0.05I.

Fracturabiliry.. showed signifi canl correlations with hardness.

adhcsiveness, cohesiveness l, resilient. sprilgiress l. gum-

miness l. and che*'iness I (p < 0-01). Similar correlations

were also observsd for hardness (p < 0.01i. Adhisivcness

cofielstcd with 8ll other characrcristics erccDt rcsilisncc and

springiusss | ftr < 0.05). Cohesiven€ss I show€d si8nificanl

effect on all characteristics exccpt adhesii'sress (p < 0-05)-

Resilience showcd signifi cant correlation with ftactdlrdbility,

bardncss, cohcsiveness l, gumrniless I (p < 0.05]. while

springiness I showed correlatioo with all other character-

istics except chewiness I ip < 0-t)5). ard gumminess I and

cohesivcncss I correlaled wrti all characteristics c\rjcpr re-

silicnt and springiness | (p < 0.05).

h the csse of p€ctin- moisture content shorved signifi-

cant corrplation with fracturability, hsrdDess, springiness I.g mminess I and chewiness l, while only adhesiveness and

resilience showed correlation with concentralion ol hvdro-

II'?\ Pri'lilc ofDatc-Tirnrnrind I earhcr

colloids. l"raclurahilrt' (and har(lness) shr)\r'cd signilicant

corrclalion $ith hardncss (or liacturability). springiness l.gunminess l. irnd chcrvincss I (p . ().05,. Adhesileness

shos'cd no conel:rt;ons $'ith all TPA chrrxctcristics {D :

0.01). while cohcsivcncss I shorvcd corrclation: onll $ithgummincss | (p. 0.05). and rcsilicncc sho\'cd corrclltiolls

!tith fracturabiliry and hardncss 1p < 0.05). Springiness I

and gunrminess I shorvcd conclations with cohesivcncss l.fncturability and hardness 1p < 0.05), chcwiness I shosed

conelations *'ith gumrnincss | , fracturabilit), and hardncss (p

< 0.00t).

ln thc cas€ of dextrin. moisture cont€nt showed signifi-

cant correlalion with frscturabilily, hardness. adhesivcness,

resilietlce, gumminess I and chewiness l. while dcxlrin

concertration showed corrclations with cohesiveness I and

springiness I (p < 0.01). Frscturabiliry and hardncss showed

corrclations with all TPA attributes except springiness I (p <

0.001). Adhesiveness showcd corrclations with all TPA char-

Ecteristics except springincss I lnd cohesiv€ness I (p < 0.05).

while cohcsiveness I conclated with springincss I, fractur-

ability and hardness (p < 0.05). Resiliencc conelated with all

TPA characleristics cxc€pt sp.inginess I and cohesiveness I

{p < 0.001). Springincss I conclated only with cohesiveness

I (p < 0.001). Gummincss I and chewiness I cor€lated whh

all TPA a8ributes cxcept springiness I and cohcsivcness I (p< 0.001).

ln thc case ofgusr gum, moisrure conlcnt showed signi6-

cant correlation with fiacturability, hardness, and lesilienc€.

while guar gum conccntration showed correlarions with only

adhesiveness (p < 0.01). Fracturability ard hardness showed

corrclations with all TPA attriburcs except resilicnce (p <

0.001). All other TPA rtbibutes did not show any inter cor-

rclations with each othcr (p < 0.05). Ho*'ever. hydrocolloids

sl 3% concentration produced a foamy and sofi puree cven

after 84 h ofdrying, thus it did not form leather. Thc abovc

results indicated that each hydrocolloid Efcctcd the me-

chqnicsl chsr,rcteristic differ€ntly, thus cluster sod priocipal

componenl analJ.sis wcrc performcd to chanctetize tlc date-

runarind fruit leafier,

Mechanical charscteristic of blanl d8k-tamarind (i.c.,

no hydrocolloids) lcather did not show any corrclation with

moisturc conEnt ranging from 4l to 29 9100 g leath€r. ex-

cept rcsiliencc (p > 0.05). Rahm& and Al-Farsi (2005) n€a-

surcd thc mcchanical characftristics of d8& as a functior ofmoisturc conted and found maximum valucs at critical mois-

ture contanr of2l.5 9/100 g below the critical moisture con-

tent therc $ss a shrrD decrcase in thc characte.istic values.

Ellecrs of di.ffercnr hrdrucolloids The cffect of different

hydrrrcolloids on thc mechanical charactcristic were evalu'

ared and compared with blank (i.e.. wirhoul hydrocolloids)

535

usjng lcitlhers fl mois|llr{ conrcnl i0: 5 g lt,1}r(\\cthasis)Results arc prcscnlcd in Tablc l.:\ddition ol hydrocollorclr

resulted in higher harlncss. gurnrrriness 0nd cherrincss.

except lbr chc\vincss in thc casc ol dc\llil. ]rnd in lo\\'cr

cohesiveness, rcsilicncc and sprrnrincss. ['lach hldroctrlkri<l

afl'ccrcd rhc charactcrisrics in ! dilirjrcnt pallcm. ,.\ll h\dro-

colloids gave leathers $,rth highcr hardncss than the blank.

Ho$cvcr. pcclin gavc lcath.'rs $ith the highesl hardness

folloqcd by starch. guar gum and dc\trin. Ilardness ofdate-

tamarind fruit lcather uith pcclin irls ncarly tl times higher

than that of dertrin rnd ? times highcr than that of strrch

and guar guDr. Similarll,pectin and srarch in combination

incrcased hardncss ol'datc paste as compared to blank (i.e..

wi*rour hydrocolloids) (Ahmcd et al-,2005l Higher pectin

contenl resulted ir higher hardness. cohesiveness, springincss

and chewiness. thus pectin level could be reduced to obtain

a softer and nrore appealing fnrit lcather (Hrang and Hsich,

2005). Gokscl et al. (201l) found that hardocss, gummincss,

and chcwincss valucs o1' grapc molasscs incrcascd with thc

starch concentration and temperaturc. This was mainly dur

to the lbrmarion ofgels with increasing gelatinized starch

content. Similar to our rcsults for dcxtrin, llaixauli et ul.

(2003) rcponed that addition of dexmn causcd a signifcaot

d€crease in peak force of fried bsner costing, indicsting

reduced hardness of thc samplcs. Thc higher hardncss val-

ues obtajncd with pecdn io this study could b€ anribuEd to

the facl that pcctin moleculcs formcd hydrogen bonds *itheach olher and cross-links that enhanced the date-tamarind

leatler's ability to resist the deformation caused by the tex-

irrc analyzer's probe as e:iplaincd by Huang and Hsich (2005)

for pear fruit leathcr

Product classilicution: Cluster anallxis .A cluster analy-

sis (considering 6.1 rypes of fiuit leathers) based on Ward's

mcthod revealcd 4 groups namcd Croup l. Croup 2, Group

3, and Group 4 ar a level of similariry/distance i4 (Figurc

2, Tablc 3). Hannon e/ al (2005) uscd principal component

and cluster analyses to classiry cheeses bssed on lheir key

chemical indices and grouped them into 5 clusters- In the

casos of l2 comorcrcial cu$ard des5erts, De Wijk el al (2003)

identified 4 clustcr groups of vanilla custard desscrts based

on sensory and iDstrumcntal mouth tbel. Thc spccific tcxtural

characrcristics of each group could bc explored by 8pplying

PCA as discussed in dre follo*.ing scction ard could bc used

to identiry wbat typcs and lcvcls ofhydrocolloids sbould be

used to develop desirEd typcs ofdate-Bmarind fruit lcathct

Ptoducl clatsificarion: Principal Conponenl .4nalvsit(PCA) T\e PCA analysis of the same groups identified o;L

clusrer analysis sho*'s five principal componcnts (84.1% of

total vadance) had an Eigcn v.lues close to | (Kaiser crtleri.

on: Rahman and.Al-Fani. 2fi15 ). These principal componens

r.:

Flg, 2. Dendogrdn oi the ciusEr analysis lbr dnlc-tamarind lhit lcalhet lGR l: Sroup Ii CR :j group 2: GR

3: group l; GR 4: Broup 4: Ihe ordcr o{ thc s nrples tfom lcli lo ri8ht arc iu follow!: CrouP | (5156. D]7(1.

Dlll4, S:41. D3lJ4, l)270. D:84). Group 2 (Sl,t6. S.l?0. S184. ti:70, S?1t4. S:li{4. P:lt4). Group i {C156.ol?0, pl?0. pt84. p:70, P-141, PJ56. P22fi. Pttx. P2,{2. n70. PllS. P)4f. P156. Ct1:. Si70. Sl.t:.D156.S156,S113, Dl42.Sl2N. l)lls. P156. C256. (i22ti. (;1a2. l)356. S.rll{. 5142. I)2{:, D15b}. Croup1(DttE. D370. Dl:8. D]4i. C-O. C-S. B0lli. R056. B0t1.l]070. lj0ti.t. Plfl;. (il8.l, (i170. c18.1, Gl2ti.C-6. C.M), For sarnple idenlrficalion. lirc lcttcr conesponds lo lh(j llr$t lc|tcr ol lhe hldrocolbid nilnre. lhefirsl digit indicates thc conccntrJrion oflhe h)'drocolloid and thc hn l\vo digrts irdicalc the ti|ne oldrying': C:commercial: B: blank. S: s[rch. P: peclini D: dcxlri|l: Cr guar Sumi O: omnge: M: mango. S: sLawberr,v]

T.bk J. gffec! ofhydrocolloids in instrumenEl TPA chaBcteristics

r-{Oi) tl^(Nt AD(Nd col(5) CV2 RE Stl{s)

abll l0a5 0

SEi l0t5 l-lPdio 3015 r-lDari. l0r5 I -l

(n&Cu!! l0+5 l-2

?:0 09 r 0.t o4r0.o 0.4r0J211!1 t.7. t,3 O:'0O 43*0.2aE+30 5r l.t Olr0.l 0:.0.013r? l.9 r l.a 0.3:0.1 l,.l t0.0:5+ t.?11.q 0J*0.1 0Jt0.l

g.: i0.0 3.il ilr: 0.9a0.1 ?J:O.l l.:i0.40.1:0.0 l.7iO:0J'0.1 5-0j:-O 5.0r !.00.4:0.1 r.9A0:0J10.1 7.0: o.0 1,.0:1.0o.l i 0.1 2.t:0.E 0.510.1 l.0r 2-o 3.0' l-0

o1,0.0 2.6* 0.ir oraao-l 80:.r.0 &o14.0

ll: | :::05 Et I l-l:0.5lo: l: l.0rl.0 l$'ll l.t-Ct-lrO:.lO .1.{r.:.t' 53 r l0 .ll.o.:0o*t 1,6:0J 9+.1 t.j I 0.8

:l l9 3-0a LO 2.1'e l.o:1.0

fiD:7: 15

54.25

t5: rl

\ihxr dr6 016 niE6 r. sedrrd dftirlisX -: [toi61G 6cnr €N: XtdrDcdldl .ocrrrdlc {g/l0 8 pdt!.I Fl FrFur:bilry (N}. HA: llt'dr|crr (}i), AD: A<tEivaB lris} C! | : ColEjvaB I l]5rcol: Coh6iJffi 2, REi R6iti*.. sPl: SFi.si6 | {r! sl?: Sgri4ind ?. GU t: C{miE | (N} Gr:- Glleiftts 2 (N), c?1, CHX CtU. CH.l: Choind l:J,a

(PC l. PC ?. PC 3, and PC,l) explaincd 3?.2, 26.5, I1.8. and

8.6 of total variance, respectively. The first axis was cor-

related with moisture contenl hardoess. and resilience and

conesponds to s d€,lcriptor ofstrength 8nd fight bock ability

(i,e,, dcformation and structural damage of first compres-

sion). The second exis was strqDgly coFelated to conccntra-

tion of hy&ocllloid aod chewiness l, and conesponds to the

elasticity (i.e.. deformstion of first snd second compression).

The third aris was strongly correlated to cohesiveness l, re-

silience and adhesiv€ness (i.e.. regain ability of the intcmal

structure and surface stickiness). The founh axis correlatcd

with gummiless I, adhesivetress. and resilicnce (i.e.. net

regain of sructur€ after first compression-decompression)

(Figue 3). The PCA of mechanical characlerislics for dat€s

at diffcrclr moislue conteot showed thal fwo factors "pias-

tic nature" and "elastic oature" of the dates are affecting lhe

process ( Rahrnan aod Al-Fani. 2005). The increase of the 5

factors afecring the date-umarind f'ruil lcathcr mochanical

charactcristics as compared to only 2 faclors in the casc ofdate fruits indicated tbe complexjt-v due io the addition oftamarind. and hydrocolloids t].?e and concenlralion.

Figure 3 presents tbe bi-plot including all date-tamarind

fruit leatbers and their coEpositio! and mechanical char-

acteristics, In the Figure 3A, the products and attrtbulcs a!€

plotted coDrid€ring principal compooen 2 veEus principal

comporcnt l. The goup I on th€ righl har|d side offte PCA

plot includes hard and chewy (i.e., hard-cbewy) leathets.

On the direction of the gummy characteristic, the group 2

includes sofi and gummy leathers (i.e.. sofl-glmmyl- The

group 4 includes hard and adhesive leathers (i.e-. h{rd-adhe-

sive). The group 3 corresponds to so{i and medium-adhesire

(i.c.. soft-adhesive) leathcrs. Thc fsrmuladon could pror ide

2 hard and 2 soft products *ith varied elastic charncteris-

tics. Figurc 3,4 shows some overlap of the groups 3 and 4.

For this reason, plots of principal component 3 and princi-

pal componenl 4 versus principal componenl I wcrc alstr

GR3 GRz

Principal Component 'l Principal Component 1

Fig. 3, A: Bi-plot of principal comJroncnt : and principal comg)nent l: B: gi-plol of principal compon!'nr 3 and princt)al com-

fnnent | [l: gn up | (Cll | ); .: Sroup : (CR 1): .: gmup 3 (GR 3): .: lroup 4 {(;lt 4): FA: Fracturabilitr: H.{: Hardness: COI:Cohesivcncss: RE: Resilicr[e: SPI i Springirrss; GU l: Cunlmrncss CH l: Chc*iressi Xl|: moislurc coolcn!: AD: adhesivenc;sl

checked (figures llrc not shou'n). Figure JB shows the plot

of principal componcnt 3 r'ersus principal component I afid

indicates bcttcr scparation ofgroup 3 and group 4. llo$,€ver

group 2 shows a mix in bcween groups 3 and 4, Thc plot ofprincipal componcnt 4 versus principal compotcnl I did nol

show any inprovcment, thus it w8s excluded. Similtrly com-

mcrci.l halwr, I dcssen (i.e., s\r,cet jelly) made up mrjnlyof starch. slgar, watcr, ghee. snd flavorcd \*iIh saffror! nuts

andor rosc watcr. $as groupcd into four classes as soft-

resilient- soff-springy-cohcsivc, soft-springy, and hard-ch€r{-y

lRaiman et al, !013). ln addirion various formularions could

be classified by close matching to the commcrcial products

(Lassoucd et aI.2008). Thereforc. this tlpe of classific.gtion

could guidc ro develop products wi$ differqnt dcsired ter-

&ral ch8ractcristics.

ColclusiollThc effects of moisture contents. and hyd.ocolloids

(tyFs and concenh'ation) showcd varicd trcnds on diffcrent

mechanical charactcrisrics ( i.e.. each hydroco I loid affected

thc characteristics in different pa0em). Sixq four fruit lcatF

en wcrc classificd into 4 classcs of fruit lca$ers as hard-

cbewy, soft-springy, hard-frsgile and sofi-rcsilicnt lcathcrs.

Thc date-tamarind fruit lesthers with 37o pectin (moistu..:

29.7 gtl00g sample), l% guar gum (moistur€: 43.4 g/100 Isample) and 2% guar gum (moisturc: I1.7 y'I00 g sanple)

matchcd the commcrcial hard-chcwy fruit ldther. Similarly

devcloped tamarind-fruit lcathcrs with 3% dcxrosc (mois-

turc: 29.3 gi 100 g sample) urd blank witbout hydrocolloid(moislure contcot:25.0 - 35.0 gl00 g samplc) matched the

commercial soff-spdngy fruit leather Thus. date-tamarind

fiuil leathcts could bc developcd by mrtching thc textural

charactcristics of commercial fruit lcathcrs.

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20t3)