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UTTLIZATION OF AMYLOSE FROM FRACTIONATEDSWEETPOTATOSTARCH*

Montatip Yunchaladt Suisano- Praditdoung2 SaipinManeepunl

ABSTRACTTo produce the amylose.film from sweet potato starch, the appropriatemethod of amylose

fractionation was found out by salting out method at l27o MgSoo solution and forming amylosecomplex with 1-BuOH in dilute hydrochloric acid. The results showed that fractionated amylose bysalting out method was not effective. It should be carried out by forming the amylose complex. Theyield of fractionated starch was 30.16Vocontaining 49.O7Vo mylose. Whereas in the large scale offractionation obtained only 25.7Voyield and 47.l5Vo amylose content. Thereby 3 formulations ofoblate type which consisted of starch and/or amylose and agar without and with glycerol asplasticizer were performed by casting method. Each formula of film showed a different dominant.property which corresponded to somc tested value for commercial cellophane. Furthermore, thesefilms also showed the excellent grease resistance which may be suitable as the internal wrappingfor a high fat content foodstuff.

INTRODUCTIONThe sweet potato (lpomoea batata) belongs to the convolvulaceaeor Morning Flory family

(Radley, 1916). lt is an enlarged root, a source of the cheap polysaccharide that was able to begrown well in every part of Thailand. Especially, it has been already promoted and developed to bethe economic plant by Government since 1987. The major component of sweet potato is a starchwhich consists of amylose and amylopectin. The starch production should have a starch content atleast 2OVo Wiersema, 1989). Mae Joe variety was selected for starch preparation in this projectbecause f its high starchcontent, ight flesh and a high amyloseabout33Vo Kalayanee,1989).

Ho.rluii'ufirfluIn:.rnt:douto.:lruii'uln:lnti Useof Sweer oraro tarch ndFlour n FoodprocessinqnvlqUUqqi lUUl0U0ln Intemational oraroCenter CIP)Instituteof Food Research nd Product Development,KasetsartUniversity,Bangkok.Department f Food Scienceand Technology,Faculty of Agro-industry,KasetsartUniversity.

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Native starches or the amylose fractionation should not be less than 20Vo amylose.Potato and comstarch were good sources to fractionate amylose (Langlois and Wagoner, 1976) as well as ricestarch (Phanorchit, 1988). The fractionated amylose could be utilized in a particular way (Gilbert etal., 1964). Due to the structure of amylose, the linear fraction of starch can be a raw materialuseful for the preparation of self-supporting film (edible film). Edible film can be defined as rhinlayer of edible material (eg. protein, lipid, polysaccharide) applied on (or even within) foods inorder to offer a selective barrier and mechanical protection too. The critical important advantageofedible film can be consumed with packaged products without disposing of the package,correspondingto reducing waste and environmental pollution. (Gennadioseand Weller. 1990).

Objectivesl. To study the appropriatemethod to fractionate amylose from sweet potato starch.2. To prepareedible film from sweet potato starch ncluding fractionatedamylose.3. To test mechanical propertiesof edible film.

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MATERIALS AND METHOD

1. Starch extraction study.The sweet potato was washed,chopped into pieces and ground with mixer machine. Sweet

potato starch extraction processwas shown in Fig. I.

Sweet potato+Washed,chopped

JWet ground in mixer machinev

SuspensionaqueousI\7Sieving vibrator

\rStarchpaste+ pulp

+Decanterv

Wet starch307o moisture contentI\yOven dry at 45'C

\rStarch

Figure I. Diagram of sweetpotato starch extraction process.

2. To analysesome chemical componentsof native starch and to observebehavior of chemical n starch.

2.1 Proximate analysis for moisture content, protein, ash and fat (acid hydrolysis) as drybasis

2.2 Amylose content(Juliano, 97l)2.3 Brightness of starch examination with Elrepho reflectometer.

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2.4 Gelatinizationemperaturey hot stagemicroscope nd viscositybehaviorbyBrabender mylograph.

3. Methods of fractionation study

3.7 Method of fractionation3.1.1 Using the liquid-liqui d phaseseparationn salt solution of MgSoo which wa s

adaptedas the optimal condition (Phanorchit, 1988) as shown in Fig. IL3.1.2 Using the solid-liquid separationby selectiveprecipitation with complexing

agent (BuOH). But in order to effect the complete dissolution of starch at temperaturebelow 100oC, Buu", and Pacsu(1953) recommended he use of di lute acid solution which wa s adaptedas theoptimal condition as shown in Fig. III.

:sa lt .1

Native sweet potato starchI MgSOo l2olol-II pH6.5-7l-I.y l :1oo ( (starch

Autoclaveat 125'C45 minures\y

Cool at 80'C 60 minutes+Centrifuge at 9000 rpm.

vPrecipitateof amylose

v cold HrOWash precipitateof salt

+ dry in ovenAmylose

IoSupernatant

Cool at 20"Cv filter

Precipitateof amylopectin\y HrO

Wash free of saltV dry in oven at 80oC

Amylopectin

amylose ractionation by salting out.

ar80c

Figure II. Optimal condition or

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Native sweet potato starchIV


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Native sweetpotato starch (25 grams,wet bassis)


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Film preparation was produced by mixing the dissolved hot starch suspensionof 5Vo (byweight) to the hot clear agar solution of 2Vo by weight) at a ratio of l:2 by heating the mixture andstirring until it became homogeneous.A certain amount of polymer solution were cast rn a thinlayer on 15x25 cm. stainlesssteel tray by hand. Cast suspensionwere dried over the slightly boilingwater bath at 40-50oC for 15 minutes, then the films were peeled off from the surface. Al l driedfilms were stored in a closed chamber at room temperature until used (time adequate forequilibrium).

In the case of the secondand the third formula which consistedof fractionated amylose. Itis necessary o dissolve amylose suspension n autoclaveat 125"C under pressure 1.5 Kg/cm2 for 20minutes, prior mixing to the agar and/or starch solution and continued the proceedingprocedure.

6. Physical properties measurment.Severalphysicalproperties f films were measured uchas the tensilestrength TS) and

elongation(E) with Tensile Testing Machine, Pendulum ype (Toyo Seiki Seisaku-Sho td.)employedTAPPI T404 OM-87. Folding endurance sing MIT. Folding EnduranceTester(ToyoSeikei Seisaku-Sho td.) employedASTM D 2176-69 reapproved, 982).TMI. ElmendorfTearTesterwasused o determinehe tearing esistancemployedTAppI T414 om-gg.

Permeability measurement.Gas permeabilityof the films were determinedwith Gas PermeabilityTester(Daventest

Ltd. Welwyn GardenDity England)employedASTM D1434-82. Grease nd oil resistance f rhefilms weredetermined y a modificationof TAPPI 454 OS-j7.

Other film characteristics.Film thicknesswas randomly measured10 locationson the testing film prior to any

measurement. micrometer hicknessester,Model 49-72TMI. (Amityville L.1. New york) wasused or this purpose. ilm surfacewasexamined singStereoMicroscopeOlympusS-2Japan).7. Statistical analysis

The experimental design used for analytical measurement was Factorial in CompletelyRandomized Design (CRD). The obtained datas were analyzed by using Analysis of Variance(ANOVA) at 1 and 5Vo level. If there were statistically significant differences in analysis ofvariance, Duncan's New Multiple Range Test used to compare between treatments.

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RESULTSAND DISCUSSION

1. Starch extraction from sweet potatoResult of starch extraction from sweet potato was obtained about 21Vo yield. Normally

starch content of sweet potato in Thailand is from l0 to 25V0,but mature root of Mae Joe varietycontained about 23-5Voof starch (Kalayanee, 1989). Isolation of starch content dependson variety,maturing and processing loss, such as grinding time, ratio of water and flesh and leachins ofsuspensionaqueous n vibrator step.

2. Analysis results.Proximate percentageanalysis of Mae Joe variety sweet potato starch were shown as dry

basis such as moisture content 11.76, protein 0.10, ash 0.38, fat 0.14 (acid hydrolysis). Madamba(1975) explained that the amount of residual protein and lipid is an index to the puriry of srarch.Only traces of protein were present in the purified starch and ash content was low. Lipid contentO.14Vowas also low. This amount of fat was not washed out with acetoneor ether but was removedby ethanol,methanol.

Amylose content of this variety of sweet potato starch was about 33vo corresponding to thesame variety of sweet potato as reported by Kalayanee (1989). Generally the optimum amylosecontent for fractionation should not be lower than 20Vo. Therefore this variety of starch isappropriate to of sweet potato starch was 90.3Vo Vo Mgo) which was rather high because he fleshof raw study the further method of separation.

The brightnesssweet potato was white.Starch grains in Figure V. are observed from photomicrograph enlarged to a final

magnification of 1000 and showed the variable shapes (oval, faceted round, polygonal) and aregenerally nonaggregated.

Under hot stage microscope, gelatinizationrange 72.5-82.5"C was obtained but mean valueol 'gelar . in izat ionemperature as '71.5"C.

Amylograph of sweet potato starch in Figure VI showed the viscosity behavior of starchpasteand pasting emperature t 78"C.

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Figure V. Native sweetpotatostarch granule1OOOX.3. Result of th e amylose ractionation.

3.I Resulf of fractionation method3.1.1 Th e amylose fiactionation fiom swcet potato starch by precipitation with

magnesium sulfate as mentioned wa s shown in Table I & II. Th e yicld of fiactionated productabout-47.34Vo wa s obtained, but the contcnt ol amylosc could not bc analysed because ofundissolvedproduct in NaOH solution.

Table I. Yield of fractionatedproduct by saltingout in lIVo magnesium ulfatesolut ion.

Starch(gram)

pH of solution6.15 6.75 fl l tered).J

b

e

f

I23

42.952t.1014.78

a52.85d28.0

e18.58

c39.21e20.3t15.07

(Value within the same column having the same etter are not significantly different at p>0.01)

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Table II. Yield of fractionatedproduct by sa lting out in magnesium ulfatesolutionand I gram of starch.

MgSO.o/o

pH of solution6.3 6.15 6.75 (filtered)

l I 42.95t2 41.3413 41.65

bc d

abc

ab c

ab52.8554.94"55.3

ed39.2rce31.46cl36. t9

(Valuc within t he samecolumn having the samc ctter trreno t signit icantlydifferent at p >0.0i)

3.1 2 Results of amylose separationby forming amylose-butanol omplex fromsweet potato starch were sunmarized in Table Ill & IV. Amount clf starch and 1-BuOH cfl 'ecteclsignif icant dift'erencton liactionatcd product. Table Ill & IV showed that the maximurn yield cl'l 'ractionated roduct to be 45.80o/o t 0.01 N HCl, but such conditions were not furthcr mcnt.ionedduc to incompletegclatinizationof cooking starch. Theref'orc hc optimum condition for amyloscseparation hould be at 0.02-5N HCl, 12.-5 ra m starchand 7.-5ml BuOH which gave 30.160lo icldwith amylose content 4L).01o/on Table lll and lV.

Table III. Yield of fractionatedproduct by precipitationwith BUOH.

Starchcontent we t basis,gram)Conccntration

of HCI (N)12.-5 l5

BuOH ml)1.5 l- ) 1.5 t5

shhshh0.i 12.53 tt.31 1r.6,r ' 10.89i l q f l c0.0,5 20.8 19.34 21 12 19.23'

0.025 30.1(," ' ' 22.J6"t 3r.81'o 24.45n"abc bc " ab0.01 31.06 35.63 45.80 42.1(t

(Value within the samc column having the same etter are not signif icantlydifferent at p> 0.05)

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Table IV Amylose content in fractionated product by precipitation with BuOH

Starch content (wet basis,gram)Conccntration t2.5 15

BuOH (ml)1.5 l5 1.5 l5

0.10.050.0250.01

41.89'abcde51.30ccle49.01e41.98

ef46.1958.98"

ab c55.31ab56.78

oh37.5l "e48.28et46.19ef46."t2

h35.43bcde50.14

abcd54.58de48.45

(Value within the same column having the same etter are not significantly different at p > 0.05)

3.2 In th c large scale preparation of fractionated amylosc,25.7Vo yield and 47.15Voamylose content were obtained. The figures showed that both yield and amylose content becamelower than the result of optimum condition in No. 3.1.2. According to the degree of rearmenrs,starch granule might be degraded and some loss of BuOH content affected on the complexformation.

4. Some properties analysis.The appearance of fractionated amylose was opaque and dense but amylopectin fraction

was clear and transparencyas shown in figure VII.

f-aiLLJ 7=aSXYMJI

1000800600400200

0

---'.-.-

60 80COOKING IME(MIN.}

100

Figure VI. Brabender amylograph shows he behavior viscosityof sweetpotatostarch.

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Figure VII. Appearance of amylose and amylopectin from sweet potato.

Another way of visualizing characteristicsof amylose and amylopectin crystals under SEMwas to observe the distinctly different shapesand sizes n Figure VIII and IX.

Figure VIII. Fractionatedamylose8OOX

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Figure IX. Fractionatedamylopectin1O OX.

Table V. Analysis of someand fractionated

physicaland chemicalproperties of native starchamvlose.

Measurements Nativc starch FractionatedamyloseMoisture content (Vo)

e

Amylose (o/o)q 1mt/e)

MW.

t l .16-12.230.475-0.523

33.62212.0980 ,860

4.09-6.530.115-0.26r

41.1527.14

79.582

Th e resultso1'thc analysiswere presentcd n Ta ble V. No t only moisture content but alsotl 'rewater activity valuc of the native starch and thc fractionatcdamylosc wcre distinctly different.Thc variation of them are surroundingdcpcndcnt, he starchan d amylose hus shouldbc kept in theclosedcontainer.

Thc amount of amylose in nativc starch and fractionatedamylosc were 33.62 and 41 75respectively. It showed that thc fractional method cannot scparate hc amylose fiaction so muchthat breeding maizc variety were developedcontaining up to 85olo mylosc in the starch (Tegge,l9ft4). Howcver the fiactionated amylosc can be providcd 1o enhancc he amount o1 amylosc innative starch.

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The intrinsic visc.ositynumber of starch component and fractionatcd amylose uslng acapillary viscometercould be measured nd molecularweight of them were consequently hown inTablc V. Due to the viscosity an d molccular size of polymer relation ha s becn shown by thegcneralequation (N ) = KM " (Greenwood,1964).

5. Film preparationThe ingredientof prepared ilms were shown n Table VI.

Table VI. Formula of film preparation.

The oblate type edible film has been performed the certain formula ingredients.The natureof starch used in the oblate formula greatly influenced the propertiesof edrble films. This is due toability of starch dispersion to form film and binding particle together or to a substrate.Whereasagar aids in high gel strerrgth fter cooking and a good stabilizer Schoch,1985).

Sfereo microscopeTo better ascertain whether dispersability of ingredient for interlacing to form network in

edible film wcre examined using stereo microscope.Results ware shown in Fig. X-XII.The surface and texture of films were noticed and presumed that the dissoved amylose

affected on the transparent of films in Fig. X - XII. Decreasing the dissolved amylose contentdecreased the fllm transparent. When the compatibility of dissolved starch and agar were stillhomogeneous, the appearance of films in Fig. X were smooth and transparent. Whereas theincomplete dissolved amylose dispersed n homogeneous solution of starch and agar. Consequentlythe opaque and more thickness of films were obtained in Fig. XI. Films in Fig. XII were opaque,dull more and more thickness, brittle and granular. Due to the undissolved amylose dispersed n aclear gel of agar.

IrormulaWeight of ingredient granr) Amounl o l amylosc in f i lm f i. 1

glycerol (7o)Starch Amylose Agar U 0.2s 0.5

l0 8 t6.32 15.44 I 4.632 5 5 8 20.56 19.43 18.423 l0 8 24.19 23.42 22.20

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Th e glycerol as plasticizcrwa s added to the film {brming solution improved softncssandflexibi l i ty. Du e to intermolecular orce bonding was weaken as well as the interlacing networkstructurcof films were also promoted.The f lms thus go t more dense.

r

&'

Surfaceof films made rom starch and agar with O.O 0.25magnification 2O x using stereo microscope.

M.

&.

ttlt?2q,!,

&$r 'S,

Figure X.

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O.6OVoglycerol,


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!- 's*$ ]

Fig. XI . Surfaceof fi lms made ro m starch-amylose nd agar with o.o, o.25, o.5o%oglycerol,magnificationl2O X usingstereomicroscope.

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o=dfu

Fig. XII. Surfaceof films made from amyloseand agar with O.O,O.25,O.\OVoglycerol, magnificationl 2O X using stereomicroscope.

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Physical properties.Film thickness varied directly to the amount of amylose and glycerol as shown in Table

VII. Film made from the mixture of starch and agar produced an appropriate thickness in the rangeof 0.0238-0.0284 mm. Film made from the mixture of starch and/or amylose and agar weregranular increasing which their transparence respectively decreased, thereby enhanced the filmthickness.

The results of physical properties (tensile strengtl. *.rd elongation, tear strength and doublefolding endurance) were presented n Table XII. The amount of amylose and glycerol influencedsignificant different on the physical properties of films. Films made from a mixture of starch andagar without glycerol produced the maximum TS. 4.65 kg/mm2 1OO+Z sl;. This film could becompared o the amylose ilm by solvent castingmethod showed TS of 5070 psi. (Mumma, 1967).Mumma also reported that cellophane film for satisficd packaging only provided the minimum TSof 3000 psi. However films madc from starch-amyloseand agar with 0.25o/oglyccrol produccd TS

2of 2.19 kg/mm (3128 psi), while fi lms madc from amylose and agar gave the lower TS value thanthc minimum TS of cellophanc,bccause f th e incomplctc dissolvcdantylosc.

Th e elongation and t car rcsistancc ncreasedas thc amount of glyccrol also increascd.While folding cnduranccvaricd indircctly to the amount of glycerol and amylosc.

Gas pcrmcability studicd o1 'plasticizedamylose f i lm showed that thc amount of glyceroiinfluenced gas permeability ratc. In crcasing the glycerol content in the filrn decrcased he ga spcrmeability rate at 27'C arrd (r57oRIJ as indicated in Tablc XIII. Corrcsponding o Banker(1966) reported hat the arrangcmcntof molecule n the film with more polar groupins are rathcr inorder, makcs lcss porous films, pennits lowcr anrount of ga s to pass through them. Whcreasdccreasing thc amylosc content resulted in de.crcasc crmeability fo r cach formula. Rut 1'or adil'fcrcnt brmula of the film. pcrrncabiiitywas independent n amylosccontcnt. According l


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Table VII. Physical properties of oblate films.

(Valuc within the samecolumn having th c same ctter ar e not significantctifl 'erentat p>0.0.5)

Table VIII. Raie of gas permeabilityof oblate 'ilms.

Fl .= slarch and agar ' i lnrFZ = starch,amyl


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CONCLUSIONIt might be able to conclude that some componentsand properties of prepared starch from

sweet potato, Mae Joe variety were investigated prior to find out the appropriate method foramylose fractionation. The finding from this study revealed that the fractionated amylose bycomplexing agent was effective. Thereby the oblate type etlible films 3 formulas were performed bycastlng method. Studied on lhe appearanceand some physical properties showed that greaseresistanceof f i lms were excellent. Thus th e feasibi l i ty of film application should be used as theinternal wrapping for a high fat content fbodstuff.

RECOMMENDATIONl . Th e amylosc fractionationby complexing agent should be further studied especiallv he

chemical residual in the fractionated product prior to adoption.2. There are some problems for dissolving the amylose at high temperature. In order to

succeed he aim of f i lm forming abil i ty the soluble propertiesof amylose should be developedbvmodifying method.

3. Oblate type film should be studied more by using a different starchcswithout amylosefractionation. Production cost and the chemical residual from fractionation may be reduced.

REFERENCESri'nurfi i'ufin::ru.532). .rfiqriiu'lifurmfl,. 3j-161untlld.rra?runr:rnun::rueurnr:

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Gilbert, L.M., G.A. Gilbert and S.P. Spragy. 1964. StarchFractions:amyloseand amylopectionfrom potato starch.p.25. ln R.L. Whistler, R.L. Smith, I.N. BeMiller and M.L. Wolform(eds.).Methods in Carbohydrate Chemistry. Vol. IV. Academic Press,New York.

Juliano, B.O.1971. Simplified assay or milled-riceamylose.Cereal Sci. Today. 16(10) : 334-360.Langlois, D.P. and J.A. Wagoner. 1967.p. 84 . In R.L. Whistler an d E.F. Paschall eds.).Starch

Chemistry and Technology Vol. II. Academic Press,New York.Meer, W. 1980.Agar, pp.7.l-7.19. In R.L. Davidson (ed.) Handbook of Water SolubleGu m ancl

Resins.McGraw Hall Book Company, New York.Mumma, C.E. 1967.Developmentof extrudedamylosepackaging ilm. Cereal Sci. Today. 12(l):4.Radley, 1.4.,1976. The Manufactureof Swect PotatoStarch.p.213. In J.A. Radley (ed.). Starch

ProductionTechnology. Applied SciencePublisherLtd., London.Schoch,T.J. 1985. Carbohydrate tarch.p. 112. In YeshajahuPomeranz ed.). Function

Properties of food Components. Food Sciencc and Technology. AVI. Academic Press.Orlando.

Tegge, G. 1984.Glucose syrup thc raw material.pp.9-64. In S.L. Dziedzic an d M.W. Kearsley(eds.).Glucose Syrups:Science nd Tcchnology. ElsevierApplied Science.Publisher.London.

Wiersema,G.S. CIP. 1989. Introduction o sweetpotato processing. Paperpresented unngTratning. Courseon Swect Pol.atoProductionand Utilization, August l-4, Thailand.

Wolff, I.A., L.J. Gundrum and C.E. Rist. 1950. A simplified procedure for the characlerizationofstarch ractionsby viscosityand iodine sorption.J. Am. Chem. Soc.72:5188.

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