characterisation of hydroxypropylated crosslinked sago starch...

ORIGINAL ARTICLE

Saowakon Wattanachant1 , Sharifah Kharidah Syed Muhammad2 ,

Dzulkify Mat Hashim3 and Russly Abd Rahman4

AbstractWattanachant, S., Muhammad, S. K. S., Mat Hashim, D. and Rahman, R. A.

Characterisation of hydroxypropylated crosslinked sago starch as compared to

commercial modified starchesSongklanakarin J. Sci. Technol., 2002, 24(3) : 439-450

The characteristics of hydroxypropylated crosslinked sago starch (HPST) were determined and com-

pared with five types of commercial modified starches (CMST) in order to evaluate its quality for

further applications. The HPST was prepared on a large scale having molar substitution (MS) and degree

substitution (DS) values in the range of 0.038 to 0.045 and 0.004 to 0.005, respectively. The properties of

HPST in terms of sediment volume, swelling power, solubility and paste clarity were 15.75%, 16.7, 8.62%

and 5.18%T650

, respectively. The MS value, phosphorus content, paste clarity, swelling power and

syneresis after six freeze-thaw cycles of HPST when compared to that of commercially available modified

starches which are normally used or incorporated in acidic, frozen and canned foods did not differ

significantly. The pasting characteristic of HPST exhibited thin to thick viscosity which was similar (P>0.05)

to that of commercial hydroxypropylated crosslinked tapioca starch (NAT 8). The acid stability, solubility

1M.Sc. (Food Science and Technology), Department of Food Technology, Faculty of Agro-Industry, Prince

of Songkla University, Hat Yai, Songkhla 90112 Thailand , 2Ph.D. (Food Chemistry), Assoc. Prof., Department

of Food Science, 3M.Sc. (Food Engineering), Department of Food Technology,

4Ph.D. (Food Technology),

Assoc. Prof., Department of Food Technology, Faculty of Food Science and Biotechnology, Universiti Putra

Malaysia, 43400 UPM, Serdang, Selangor D.E. Malaysia.

Corresponding e-mail : [email protected]

Received, 18 October 2001 Accepted, 3 January 2002

Characterisation of hydroxypropylated crosslinked sago

starch as compared to commercial modified starches

Characterisation of hydroxypropylated crosslinked sago starch

Wattanachant, S., et al.Songklanakarin J. Sci. Technol.

Vol. 24 No. 3 Jul.-Sep. 2002 440

Native sago starch needs to be modified toimprove its quality. The suitability of native sagostarch as a base for hydroxypropylation andcrosslinking has been studied (Wattanachantet al., 2002). The effect of hydroxypropylationand crosslinking on dual-modified sago starchproperties has been reported and discussed (Wat-tanachant and Muhammad, 2001; Saowakonet al., 2001). However, physicochemical pro-perties of modified starch are important for foodmanufacturers in terms of quality control and cri-

teria for selecting starches capable of impartingspecific requirements. Furthermore, the measure-ment of chemical residual is necessary for foodsafety. Inclusively, the physical properties of thedual-modified sago starch should be considered,and are compared to that of commercially avail-able modified starches in order to ascertainwhether the former can be an alternative modifiedstarch source.

The applications of modified starches infood can be divided into three groups based on

and freeze-thaw stability of both starches were also similar (P>0.05) but the swelling power of HPST was

slightly lower (P<0.05) than that of NAT 8 .

Key words : sago starch, modified starch, hydroxypropylation, crosslinking, starch properties, starch characterisation, commercial starch

∫∑§—¥¬àÕ

‡ “«§π∏å «—≤π®—π∑√å 1

™“√‘ø“Àå ¶“√’¥“ ´“¬¥å ¡ŸŒ“À¡—¥2

´Ÿ°√‘øøïò À¡—¥ Œ“´‘¡3

·≈– √Ÿ √’ √“Àå¡“π3

°“√»÷°…“≈—°…≥–¢Õß·ªÑß “§Ÿ¥—¥·ª√‚¥¬°√–∫«π°“√‰Œ¥√Õ°´’‚æ√æ‘≈‡≈™—π·≈–

§√Õ √‘ß§å„π‡™‘ß‡ª√’¬∫‡∑’¬∫°—∫·ªÑß¥—¥·ª√∑“ß°“√§â“

«. ß¢≈“π§√‘π∑√å «∑∑. 2545 24(3) : 439-450

≈—°…≥–¢Õß·ªÑß “§Ÿ¥—¥·ª√‚¥¬°√–∫«π°“√‰Œ¥√Õ°´’‚æ√æ‘≈‡≈™—π·≈–§√Õ √‘ß§å‰¥â∂Ÿ°»÷°…“·≈–‡ª√’¬∫‡∑’¬∫

°—∫·ªÑß¥—¥·ª√∑“ß°“√§â“®”π«π 5 ™π‘¥ ‡æ◊ËÕª√–‡¡‘π≈—°…≥–§ÿ≥¿“æ·≈–‡ªìπ¢âÕ¡Ÿ≈ ”À√—∫°“√„™âª√–‚¬™πå„π

Õÿµ “À°√√¡Õ“À“√µàÕ‰ª ·ªÑß “§Ÿ¥—¥·ª√ (HPST) ¡’§à“‚¡‡≈°ÿ≈∑¥·∑π·≈–¥’°√’¢Õß§√Õ √‘ß§åÕ¬Ÿà„π™à«ß 0.038-

0.045 ·≈– 0.004-0.005 µ“¡≈”¥—∫ ”À√—∫§ÿ≥ ¡∫—µ‘¢ÕßπÈ”·ªÑß ÿ°æ∫«à“ ¡’‡ªÕ√å‡´Áπµå°“√µ°µ–°Õπ¢Õß‡¡Á¥·ªÑß∑’Ë

æÕßµ—«‡∑à“°—∫ 15.75% ¡’°”≈—ß°“√æÕßµ—«¢Õß‡¡Á¥·ªÑß °“√≈–≈“¬ ·≈–§«“¡„ ‡∑à“°—∫ 16.7 8.68% ·≈– 5.18%T650

µ“¡≈”¥—∫ ´÷Ëß§à“‚¡‡≈°ÿ≈∑¥·∑π ª√‘¡“≥øÕ øÕ√— §«“¡„ °”≈—ß°“√æÕßµ—« ·≈–ª√‘¡“≥¢Õß‡À≈«À≈—ß®“°ºà“π

°“√·™à·¢Áß-∑”≈–≈“¬®”π«π 6 √Õ∫¢Õß·ªÑß “§Ÿ¥—¥·ª√‰¡à¡’§«“¡·µ°µà“ßÕ¬à“ß¡’π—¬ ”§—≠∑“ß ∂‘µ‘ ‡¡◊ËÕ‡ª√’¬∫‡∑’¬∫

°—∫§ÿ≥ ¡∫—µ‘¢Õß·ªÑß¥—¥·ª√∑“ß°“√§â“∑’Ëπ‘¬¡„™â„πÕ“À“√∑’Ë¡’§«“¡‡ªìπ°√¥ Õ“À“√·™à·¢Áß ·≈–Õ“À“√°√–ªÜÕß∑’Ë

ºà“π§«“¡√âÕπ Ÿß ≈—°…≥–°“√‡ª≈’Ë¬π·ª≈ß§«“¡Àπ◊¥¢Õß·ªÑß “§Ÿ¥—¥·ª√ (HPST) ‡ªìπ·∫∫§«“¡Àπ◊¥µË”¢≥–„Àâ

§«“¡√âÕπ·≈–§«“¡Àπ◊¥‡æ‘Ë¡ Ÿß¢÷Èπ¢≥–∑‘Èß„Àâ‡¬Áπµ—« ‚¥¬¡’≈—°…≥–°“√‡æ‘Ë¡§«“¡Àπ◊¥·∫∫‡¥’¬«°—∫·ªÑß¡—π

”ª–À≈—ß¥—¥·ª√∑“ß°“√§â“ (NAT 8) ·ªÑß “§Ÿ¥—¥·ª√¬—ß¡’§«“¡§ßµ—«µàÕ ¿“«–°√¥ §«“¡§ßµ—«µàÕ°“√·™à·¢Áß-∑”

≈–≈“¬ ·≈–°“√≈–≈“¬ ‡™àπ‡¥’¬«°—∫·ªÑß∑“ß°“√§â“ NAT 8 (P>0.05) ·µà¡’°”≈—ß°“√æÕßµ—«¢Õß‡¡Á¥·ªÑßµË”°«à“·ªÑß

NAT 8 ‡≈Á°πâÕ¬ (P<0.05)

1

¿“§«‘™“‡∑§‚π‚≈¬’Õ“À“√ §≥–Õÿµ “À°√√¡‡°…µ√ ¡À“«‘∑¬“≈—¬ ß¢≈“π§√‘π∑√å Õ”‡¿ÕÀ“¥„À≠à ®—ßÀ«—¥ ß¢≈“ 90112 2

¿“§

«‘™“ Food Science 3

¿“§«‘™“ Food Technology §≥– Food Science and Biotechnology, ¡À“«‘∑¬“≈—¬ Universiti Putra Malaysia

43400 ¡“‡≈‡´’¬

Songklanakarin J. Sci. Technol.

Vol. 24 No. 3 Jul.-Sep. 2002 441


Wattanachant, S., et al.

the types of food involving: acidic, frozen andcanned foods. Many types of modified starchesare commercially available to be incorporated inthese food products; however, all of them are pro-duced from waxy corn and tapioca starches. Inthis study, therefore, the characteristics of thehydroxypropylated crosslinked sago starch weredetermined and compared with those of commer-cially modified starches in order to evaluate itsquality for further applications.

Materials and Methods

The native sago starch used was obtainedfrom Ajinomoto Co. Ltd. Five types of commer-cially modified starches derived from waxy corns(Clearjel, Colflo97, NAT 1390S, and NAT 1333)and tapioca (NAT 8) obtained from NationalStarch and Chemical (M) Sdn. Bhd were used inthis study. Types of modification, properties anduses of these commercially modified starches areshown in Table 1. Their pasting characteristics

Table 1. Types of commercially modified starches.

Sample Starch base Modification Properties and Use

Source: Information from National Starch and Chemical (Malaysia) Co., Ltd.

Clearjel

Colflo 67

Nat 1390S

Nat 1333

Nat 8

Waxy corn

Waxy corn

Waxy corn

Waxy corn

Tapioca

Medium cross-link

Medium stabiliseMedium cross-link

Medium stabiliseLess cross-link

Medium stabiliseHigh cross-link

High stabiliseMedium cross-link

More sourJelly product in can/container

More sourBottle sauces

Less harsh cooking condition

Harsh cooking condition e.g. High shearing

Not sour, bland taste, hot viscosity is lower thanwaxy corn but cold viscosity is the same

Table 2. Pasting characteristic of commercially modified starches at the condition of

6.0% starch solid, pH 3.5 and 6.5.

pH 3.5 6.5 3.5 6.5 3.5 6.5 3.5 6.5 3.5 6.5

Viscosity (BU)

After 30 min

(H)

Pasting temp.

(o

C) 95

o

C 50 o

C (C)

ClearjelColflo 67Nat 1333Nat 1390SNat 8

63.060.058.560.051.0

66.061.560.061.552.5

780750545700725

695755560715440

10251045 995 890 750

10351230122511401150

13701305153010801410

13951535172015152035

345260535190660

360305495375885

Consistency

(BU)

(C-H)

Sample



Vol. 24 No. 3 Jul.-Sep. 2002 442

at neutral and acidic pH were determined in aBrabender Amylograph and their paste proper-ties are presented in Table 2 and 3, respectively.

Preparation of hydroxypropylated crosslinked

sago starch

Sago starch was doubly modified in dupli-cates of six batches by hydroxypropylation andcross-linking with 12% propylene oxide and amixture of 2% STMP and 5% STPP at 40 oCfor 24 and 2 hours, respectively; as described inprevious researches (Wattanachant and Muham-mad, 2001; Saowakon et al., 2001). Resultsfrom preliminary studies indicated that treatmentof sago starch with 10-12% propylene oxide andthis mixture of phosphate salts yielded the bestdistarch phosphate (crosslinking) with optimumsubstitution (Saowakon et al., 2001). However,the preparation of hydroxypropylated cross-linked sago starch in several batches resulted inless stable pasting characteristic at 10% propyleneoxide level. Hereupon, the dual-modified sagostarch at 12% propylene oxide was selected forthis study.

Determination of phosphorus content

The content of phosphorus in starch wasdetermined in four replicates for each sample bythe method of Egan et al. (1981).

Degree of substitution (DS) and molar substi-

tution (MS)

The extent of hydroxypropylation of modi-fied starch was determined according to Johnson(1969). The degree of substitution (DS) and themolar substitution (MS) were calculated in thenormal fashion (Rutenberg and Solarek, 1984).

Pasting characteristics

The pasting of starch samples was exam-ined in a Brabender Amylograph at 6% starchsolid and pH 6.5, which is similar to the proce-dure described by Wattanachant and Muhammad(2001). The following measurements were takenfrom the Amylograph curve: the pasting temp-erature, the peak consistency during the heatingstage, the consistency after being held for 30 minat 95 oC and the consistency after cooling to 50 oC.T

ab

le 3

.P

ast

e p

rop

erti

es o

f co

mm

erci

all

y m

od

ifie

d s

tarc

hes

.

S

edim

ent

S

olu

bil

ity

Fre

eze-

thaw

v

olu

me

A

t 85 o

C st

ab

ilit

y

(m

l) (

%)

(%

syn

eres

is)

Cle

arje

lC

olfl

o 67

Nat

133

3N

at 1

390S

Nat

8

0.01

0.08

0.08

0.08

0.05

0.00

60.

006

0.00

70.

005

0.00

6

5.20

6.00

4.50

3.40

3.00

19.0

25.4

26.0

30.5

17.5

14.6

716

.90

14.2

019

.54

16.8

5

3.20

4.15

3.52

4.58

7.23

28.7

5 1

.30

1.0

725

.43

0.7

1

43.7

32.8

34.0

27.3

20.8

Mea

n±sd

0.06

±0.

030.

006±

0.00

1

4.4

2±1.

24

23.

7±5.

36

16

.43±

2.13

4

.53±

1.60

1

1.45

± 1

4.33

31.7

±8.

5

Sam

ple

M

SP

con

ten

t

(%)

Cla

rity

%T

650

Sw

elli

ng p

ow

er

At

85 o

C

Gel

str

ength

(g)


Vol. 24 No. 3 Jul.-Sep. 2002 443



Acid stability

To determine the acid resistance on starchpaste, a few drops of 30% acetic acid solutionwas used to adjust the pH of starch slurry to 3.5 tosimulate pasting of starch having nearly the samepH of high-acid food. The pasting of starch sam-ples was examined in a Brabender Amylographand the procedure was similar to the examinationof pasting behaviour at pH 6.5.

Paste clarity

The clarity (% T650

) of a 1% starch pastewhich had been heated in a boiling water bath for30 min and cooled to 25 oC for one hour wasevaluated using percent transmittance at 650 nmagainst a water blank in a spectrometer (Kerr andCleveland, 1959).

Sediment volume

Sediment volume was determined as des-cribed by Tessler (1978). One gram of starchbased on dry basis was weighed into a beakerand 95 ml of distilled water was then added.The pH of the starch slurry was adjusted to pH7.0 using 5% NaOH or 5% HCl, followed whichthe slurry was cooked in a boiling water bath for15 min. Distilled water was then added to bringthe total weight to 100 g. The mixture was thenstirred thoroughly and transferred to a 100 mlgraduated cylinder. The cylinder was sealed withaluminium foil and the starch slurry was kept atroom temperature for 24 hr. The volume of thesediment, consisting of swollen starch granules,was then measured.

Swelling power and solubility

Swelling power and solubility were deter-mined as described by Schoch (1964).

Freeze-thaw stability

Freeze-thaw stability was expressed as thepercentage of water separated from 20 g each ofthe gels (8% starch solid) after each freeze-thawcycle. The procedure was modified from Takaha-shi et al. (1989) and Wu and Seib (1990). A starch

solution (8% starch solid) was adjusted to pH 6.5and heated to 95 oC, holding at 95 oC for 30 minand cooled to 50 oC in a shaking water bath.After cooling at 50 oC, starch paste was weighed(accurately 20 g each) into known weight 50 mlconical centrifugal tubes which were sealedtightly with screw caps. The tubes were shelvedfor 24 hr at 4 oC followed by freezing at -20 oCfor 48 hr and thawing for 4 hr at 25 oC. Then thefreeze-thaw stability was measured as the per-centage of water separated on alternate freezingand thawing of the pastes followed by centrifuga-tion at 3000 rpm for 15 min. The percentage ofsyneresis was the ratio of the weight of the sepa-rated water to the weight of the paste. In this study,six freeze-thaw cycles were conducted.

Gel strength

The texture of a gel (8% starch solid) wasdetermined in four replicates using a StableMicro Systems (TAXT-2 Texture Analyser). To pre-pare gels, the procedure described by Taka-hashi et al. (1989) was followed. All starcheswere adjusted to pH 6.5 using 5% NaOH or 5%HCl solution before cooking from 30 to 95 oC,held at 95 oC for 30 min , and then cooled to 50 oC.The hot paste was poured to a height of 2.7 cminto a cylindrical plastic container (diam. = 4.0 cm,height 5.5 cm) and stored for 24 hr at 25 oC and4 oC before measurement. For gel strength meas-urements, the gels were compressed at a speed2.0 mm/sec to a distance of 15 mm (Takahashi etal., 1989) using a cylindrical plunger (diam.= 10mm). For gels, the maximum force during com-pression was considered as the gel strength andfor pastes, the maximum force of deformation at15 mm compression was regarded as ‘gelstrength’. The paste and gel characteristics wererecorded by visual evidence.

Statistical analysis

The data were analysed using the two-sam-ple t-test assuming equal variances and the pairedtwo sample t-test for means to evaluate the differ-ence of means (Steel and Torie, 1980).



Vol. 24 No. 3 Jul.-Sep. 2002 444

Results and Discussion

Chemical control measurement

In the fact that each starch needs to be mo-dified to increase its usefulness but it is unlikelythat any new derivatives or degree of substitutionwill be allowed (BeMiller, 1997). In this study,therefore, the degree of substitution and phospho-rus content of modified sago starch were control-led being in the range of commercially availablemodified starches and followed the U.S. regula-tion of CFR (1991) cited by Lim and Seib (1993).The hydroxypropylated crosslinked sago starchthat was prepared in six batches exhibited MSand degree of crosslinking (DS) in the range of0.038 to 0.045 and 0.004 to 0.005, respectively.The accumulated dual-modified sago starch(HPST) was re-sampled to determine the MS, DSand P content so as to compare with the meansof the results of five commercially modifiedstarches (CMST). Table 4 shows the properties ofHPST and CMST which had MS values that wereclose to each other (P>0.05). P content of HPSTwas 0.097% which was lower than the maximum

level (0.4%) allowed by the U.S. regulation. How-ever, the value was significantly lower (P<0.01)for CMST. The reason could be due to the differ-ent types of crosslinking reagents employed inthe commercial modification of starches. Themixture of STMP and STPP was reported to im-part high P content ranging from approximately0.3 to 0.5% in the phosphorylation of wheat andcorn starches (Lim and Seib, 1993).

Physical characteristics

Crosslinking could have a profound effecton the paste properties of cooked starch bystrengthening the granules to resist rupturing andimpart to a short salve-like texture at the cookedsols while hydroxypropylation is known to pro-duce soft paste (Wurzburg, 1986; Tuschhoff,1986). Figure 1 illustrates the effect of hydro-xypropylation and crosslinking on the texture ofcooked paste of dual-modified sago starch. Thesample on the right was hydroxypropylated andcrosslinked at which MS 0.033 and DS 0.004achieved in counteracting the cohesive elastic gelof the native sago starch (Saowakon et al., 2001).

Table 4. Physicochemical properties of hydroxypropylated crosslinked sago starch (HPST) and

commercially available modified starches (CMST) for application in canned, high acid

and frozen foods.

Starch Properties HPST/a

CMST/b

P (T < t) two-tail

MSP content (%)Paste clarity (%T

650)

Sediment volume (ml)Swelling power

/c

Solubility/c (%)

Gel strength/d (g)

Syneresis/e (%)

0.041 ± 0.0030.097 ± 0.003 5.18 ± 0.0515.75 ± 0.9616.70 ± 0.29 8.62 ± 0.2210.60 ± 0.88 1.14 ± 0.15

0.060 ± 0.0310.006 ± 0.001 4.42 ± 1.2423.48 ± 5.2716.43 ± 2.13 4.55 ± 1.6231.72 ± 8.5011.45 ± 14.33

0.2599.579 × 10

-11

0.2690.0240.8140.0020.0020.197

Note:/a

The average mean of four determinations/b

The average mean for five types of commercially modified starches , Clearjel, Cloflo97, Nat 1333,

Nat 1390S, Nat 8 (as shown in Table 3)/c

Swelling power and solubility at 85o

C/d

Starch-water slurry at pH 6.5 with 8% starch solid cooked in a closed water bath from 30 to 95o

C,

held at 95o

C for 30 min, cooled to 50o

C, then poured into moulds and aged for 24 hr at 25o

C./e

Percent syneresis of starch pastes or gels after 6 freeze-thaw cycles


Vol. 24 No. 3 Jul.-Sep. 2002 445



Figure 1. Textural of gel and paste property of the native sago and hydroxypropylated

crosslinked sago starch with MS 0.033/DS 0.004

In addition, the undesirable reddish colour of sagostarch gel was removed as evidenced visuallyfrom Figure 1. However, the reason why the col-our of sago starch gel could be improved afterundergoing hydroxypropylation and crosslinkingis still not known. In order to evaluate the qualityof the hydroxypropylated crosslinked sago starch(HPST), the important physical properties wereexamined comparatively with the average meanof the data obtained using five commerciallymodified starches (CMST) which were Clearjel,Colflo97, Nat 1390S, Nat 1333 and Nat 8 asillustrated in Tables 4 and 5. The t-test was used tocompare the means of the two samples.

Paste and gel properties

HPST and CMST did not differ significant-ly in their paste clarity, swelling power, andfreeze-thaw stability (P>0.05) but their sedimentvolume (P<0.05), solubility and gel strength(P<0.01) differed as shown in Table 4. The pasteclarity, swelling power and solubility of HPSTwere higher than that of CMST whereas the per-cent syneresis of the former starch after 6 freeze-thaw cycles was much lower than that of thelatter. This indicated that HPST was more freeze-

thaw stable than the commercially modifiedstarches.

CMST exhibited high syneresis with amean value of 11.45% and a high standard de-viation that was caused by the difference in thestarch base and modification method used in thepreparation of commercially modified starches(Yeh and Yeh, 1993; Wu and Seib, 1990). Accord-ing to Wu and Seib (1990), most modified waxymaize starch had poorer freeze-thaw stability thansimilarly modified tapioca starch. In addition,modification methods were also reported to affectthe freeze-thaw stability of starch. For instance,hydroxypropylation was more effective in im-proving freeze-thaw stability than acetylationwhile crosslinking decreased this property (Wuand Seib, 1990).

The lower sediment the volume of HPSTmay indicate that sago starch experienced a great-er degree of crosslinking than CMST. However,the type of starches used may have an influenceon this. The obvious difference between HPSTand the commercially modified starches was inthe gel strength. HPST (8% starch solid) did notform gel after ageing at 25 oC for 24 hours and



Vol. 24 No. 3 Jul.-Sep. 2002 446

had a lower gel strength (P<0.01) when comparedto that of the commercially modified starches.

Pasting characteristics

Table 5 illustrates that the pasting temp-erature of HPST was similar to that of CMST(P>0.05) and the HPST exhibited thin to thickviscosity. Its hot paste viscosity at 95 oC and afterholding at 95 oC for 30 min was significantlylower (P<0.01) than that of CMST. After the cool-ing period at 50 oC, its cold paste viscosity in-creased to the same range as that of CMST (P>0.05). For food production, the viscosity of starchpaste is a property that needs to be considered,particularly if special equipment has to be usedduring the production of the item. For example, inthe retorting of canned foods, thin-thick viscosityis the most desirable property of the starch thick-ener (Tessler, 1975; Valle et al., 1976). Further-more, HPST showed a higher paste consistencyalthough the value was not significantly different(P>0.05) from that of CMST at the neutral condi-tion of pH 6.5.

The determination of acid resistance ofboth modified starches was conducted at pH 3.5,

achieved by adjusting with acetic acid solution.Both HPST and CMST had reduced pasting tem-peratures from 60.0 oC and 60.3 oC at pH 6.5,respectively, to 58.5 oC at pH 3.5. The hot pasteviscosity at 95 oC was remarkably higher for bothmodified starches, at pH 3.5 than at pH 6.5 sincehydrogen bonding in starch granules was weak-ened by acid hydrolysis, resulting in the starchswelling at a faster rate. However, acid treatmentresulted in a reduction in the cold paste viscosityand paste consistency of these modified starches.The consistency of HPST was higher but its vis-cosity was lower than that of CMST. The acidresistance of HPST was acceptable when com-pared to that of the commercially modified starchesand its pasting characteristic did not differ signi-ficantly (P>0.01) from that of CMST as illus-trated in Table 5.

Quality of hydroxypropylated crosslinked sago

starch

It is known that the viscosity of native sagois similar to that of native tapioca starch (Wat-tanachant et al., 2002). Through the same method

Table 5. Pasting characteristics of hydroxypropylated crosslinked sago starch (HPST) and

commercially available modified starches (CMST) for application in canned, high

acid, and frozen foods.

Characteristics HPST/a

CMST/b

P (T < t) two-tail

At pH 6.5

-Pasting Temp. -Viscosity at 95

oC

-Viscosity after 30 min -Viscosity at 50

oC

-ConsistencyAt pH 3.5

-Pasting Temp. -Viscosity at 95

oC

-Viscosity after 30 min -Viscosity at 50

oC

-Consistency

60.0 ± 0.0 50.0 ± 7.1 780.0 ± 42.4 1670.0 ± 28.3 890.0 ± 484.0

58.5 ± 0.0 470.0 ± 14.1 590.0 ± 28.3 1042.0 ± 45.9 452.5 ± 17.7

60.3 ± 4.9 633.0 ± 130.4 1156.0 ± 79.3 1640.0 ± 249.6 484.0 ± 234.6

58.5 ± 4.5 700.0 ± 91.6 941.0 ± 122.3 1339.0 ± 166.4 398.0 ± 195.3

0.9380.0020.0020.8790.071

1.0000.0200.0120.0650.725

Note:/a

Data are mean of duplicate determinations/b

Data are mean of duplicate determination for five types of commercially available modified starches;

Clearjel, Colflo97, Nat 1333, Nat 1390S and Nat 8 (as shown in Table 2)


Vol. 24 No. 3 Jul.-Sep. 2002 447



Figure 2. Amylograms of hydroxypropylated crosslinked sago starch (HPST) and hydroxypropylated

crosslinked tapioca starch (NAT 8) at 6% starch solid, pH 6.5 (A) and pH 3.5 (B).

Table 6. Pasting characteristics of hydroxypropylated crosslinked sago starch (HPST) and com-

mercial hydroxypropylated crosslinked tapioca starch (NAT 8) at different pH conditions.

Pasting Characteristic HPST NAT 8 P (T < t) two-tail/a

Note: - /a

t-Test: Paired two samples for means of two starch types

- /b

t-Test: Paired two samples for means of two pH conditions

- Data presented are the grand average means of viscosity (BU) at 95 o

C, viscosity after holding at 95 o

C

for 30 min, viscosity at 50 o

C and paste consistency in duplicate determinations.

At pH 6.5At pH 3.5

690.0 ± 673.6522.7 ± 352.8

905.8 ± 753.1801.8 ± 556.0

0.1400.038

P (T < t) two-tail/b

0.408 0.446 ns (P > 0.05)

of modification, therefore, a similar pasting char-acteristic should be obtained with HPST andthe commercially hydroxypropylated crosslinkedtapioca starch (NAT 8). The amylograms of bothstarches are shown in Figure 2. In order to evaluate

the quality of HPST as compared to that of NAT 8,various critical points in their pasting behaviorswere noted and analysed using Student’s t-test.

Heat and acid resistance

Both starches showed high heat and shear

resistance as affirmed by no viscosity breakdownas illustrated in Figure 2. In addition, Table 6 pre-sents the pasting characteristics of both starchesin different pH conditions to evaluate the acid re-sistance of HPST and NAT 8. Results of a two-tailed t-test indicate that both starches were acidresistant because the mean of pasting characteris-tic of both starches was not significantly affectedby acidic condition (P>0.05). However, HPSThad significantly lower viscosity (P<0.05) than NAT



Vol. 24 No. 3 Jul.-Sep. 2002 448

Table 7. Some properties of hydroxypropylated crosslinked sago starch (HPST) and

commercial hydroxypropylated crosslinked tapioca starch (NAT 8).

Starch Properties HPST NAT 8 P (T < t) two-tail/a

Note: -/a

t-Test: Paired two sample for means of two starch types

-/b

Swelling power and solubility at the temperature of 65, 75, 85 and 95 o

C.

-/C

Syneresis after 1 to 6 freeze-thaw cycles

- Data presented are the grand average means of four determinations.

Swelling power/b

Solubility/b (%)

Syneresis/c (%)

15.09 ± 1.74 7.39 ± 1.18 1.04 ± 0.14

18.06 ± 1.30 6.94 ± 0.45 0.93 ± 0.17

0.0420.3900.056

Figure 3. Swelling power of native (NT), hy-

droxypropylated crosslinked sago starch

(HPST) and hydroxypropylated cross-

linked tapioca starch (NAT 8).

Figure 4. Solubility of native (NT), hydroxy-

propylated crosslinked sago starch

(HPST) and hydroxypropylated cross-

linked tapioca starch (NAT 8).

8 at pH 3.5.Swelling power and solubility

The viscosity of HPST was lower than thatof NAT 8 since the former starch had lower swell-ing power (P<0.05) than the latter as shown inTable 7. The swelling power of HPST and NAT 8were 15.09 and 18.06, respectively, while theirsolubility was not significantly different (P>0.05). Generally, the native sago starch wasreported to have higher swelling power and solu-bility than the native tapioca starch (Pomeranz,1991). The lower swelling power of HPST ob-

served in this study may be due to the higherdegree of crosslinking obtained when comparedto that of NAT 8.

Hydroxypropylation and crosslinking alteredthe swelling power and solubility of native sagostarch as illustrated in Figures 3 and 4. As thetemperature was increased, the native sago starchexperienced a rapid increase in swelling powerand solubility. However, these properties of theHPST were almost unaffected by the increase intemperature and a similar observation was madewith NAT 8. It was noticed that HPST had higher


Vol. 24 No. 3 Jul.-Sep. 2002 449



swelling power and solubility than the nativesago starch at 65 oC. This is because hydroxy-propylation reduces hydrogen bonding insidethe starch granules, resulting in a reduction in thetemperature required for hydration.

Freeze-thaw stability

The syneresis exhibited by HPST did notdiffer significantly (P>0.05) from that of NAT 8after 1 to 6 freeze-thaw cycles (see Table 7) but itwas lower than that experienced by native sagostarch as illustrated in Figure 5. These resultsindicate that HPST with its high freeze-thawstability could be used as an alternative of NAT 8in frozen food products.

Conclusions

Hydroxypropylated crosslinked sago starchhad pasting characteristics and paste propertiesalmost in the range obtained with commerciallyavailable modified starches used in high acid,frozen and canned foods except for its gelstrength. It exhibited excellent thin-thick viscos-

ity behaviour which is a desirable property forheat-processed products such as canned foods. Itwas also heat, shear and acid resistant, and hadhigh freeze-thaw stability suitable for cold stor-age. Its behaviour was similar to that of a com-mercial dual-modified tapioca starch (NAT 8)except in its ability to be a thickening agent. Thus,it can be used as an alternative to NAT 8 in foodproduction except that a slightly higher amountof the former than the latter should be used toachieve the same viscosity.

References

BeMiller, J. N. 1997. Starch modification: challengesand prospects. Starch/Starke. 49(4) : 127-131.

Egan, H., Kirk, R. S., and Sawyer, R. 1981. Pearson’schemical analysis of food. 8th ed. ChurchillLivingstone London. p.29-30.

Johnson, D. P. 1969. Spectrophotometric determina-tion of the hydroxypropyl group in starch ethers.Anal. Chem. 41: 859-860.

Kerr, R. W. and Cleveland, F. C. 1959. Orthophosphateesters of starch. US Patent. 2884413.

Lim, S. and Seib, P. A. 1993. Preparation and pastingproperties of wheat and waxy corn starch phos-phates. Cereal Chem. 70: 137-144.

Pomeranz, Y. 1991. Functional properties of food com-ponents. (2nd ed.). Academic Press, Inc. p.24-78.

Rutenberg, M. W., and Solarek, D. 1984. Starch deri-vatives: production and uses. Pages 311-388 inR. L. Whistler, J. N. BeMiller, and E. F. Paschall,eds., Starch chemistry and technology, 2nd ed.Academic Press: Orlando, FL.

Saowakon W., Kharidah M., Dzulkify M.H. andRussly Abd R. 2001. Effect of crosslinkingreagents and hydroxypropylation levels ondual-modified sago starch properties. Foodchem. (in press)

Schoch, T. J. 1964. Swelling power and solubility ofgranular starches. Pages 106-108 in R. L. Whis-tler, ed., Methods of carbohydrate chemistry,Vol.4. Academic Press: New York.

Steel, R. G. D. and J. H. Torie. 1980. Principles andprocedures of statistics (A Biometric approach).2nd ed. McGraw-Hill: New York.

Figure 5. Freeze-thaw stability of native (NT),

hydroxypropylated crosslinked sago

starch (HPST) and hydroxypropylated

crosslinked tapioca starch (NAT 8).



Vol. 24 No. 3 Jul.-Sep. 2002 450

Takahashi, S., Maningat, C.C. and Seib, P. A. 1989.Acetylated and hydroxypropylated wheatstarch: paste and gel properties compared withmodified maize and tapioca starches. CerealChem. 66: 499-506.

Tessler, M. M. 1975. Hydroxypropylated, inhibitedhigh amylose retort starches. US Patent. 3904601.

Tessler, M. M. 1978. Process for preparing cross-linkedstarches. US Patent. 4098997.

Tuschhoff, J. V. 1986. Hydroxypropylated starches.Pages 89-96 in O.B. Wurzburg, ed., Modifiedstarches: properties and uses. CRC Press, Inc.Florida.

Valle, F., Tuschoff, J. V. and Streaty, C. E. 1976. Thin-thick retort starch derivatives. US Patent.4000128.

Wattanachant, S. and Muhammad, S.K.S. 2001. Ef-fects of hydroxypropylation and crosslinkingon dual-modified sago starch properties. Song-klanakarin J. Sci. Technol. 23(4): 555-562.

Wattanachant, S., Muhammad, S.K.S., Mat Hashim,D. and Rahman, R.A. 2002. Suitability of sagostarch as a base for dual-modification. Song-klanakarin J. Sci. Technol. 24(3) : 431-438.

Wu, Y. and Seib, P. A. 1990. Acetylated and hydroxy-propylated distarch phosphates from waxybarley: paste properties and freeze-thaw stabil-ity. Cereal Chem. 67: 202-208.

Wurzburg, O. B. 1986. Cross-linked starches. Pages41-53 in O. B. Wurzburg, ed., Modified Starches:Properties and Uses. CRC Press, Inc., Florida.

Yeh AN-I and Yeh Su-Lan. 1993. Some characteristicsof hydroxypropylated and cross-linked ricestarch. Cereal Chem. 70: 596-601.

characterisation of hydroxypropylated crosslinked sago starch...

Documents