GELATION OF STARCHES IN PLANT GUMS SOLUTIONS

Marek Sikora, Stanisław KowalskiMagdalena Krystyjan, Piotr Janas,

Hanna Baranowska & Piotr Tomasik

Faculty of Food TechnologyUniversity of Agriculture, Kraków

Materials� Starches:� Potato - was isolated in our laboratory from

potatoes of the Glada variety, collected from the experimental farm in Wegrzce at Krakow, Poland.

� Tapioca - purchased from National Starch & Chemicals, GmbH in Hamburg, Germany.

� Corn - purchased from Dia-Cel in Lodz, Poland. � Oat - isolated from oat, according to Paton

[1977].

Materials

� Arabic gum, � carob gum, � guar gum, � karaya gum, � xanthan gum � k-carrageenan were purchased from

Sigma St. Louis, MO, USA.

Methods

� Average molecular weight (starches + gums) � Mn andMw and polydispersity,

� Gelation characteristics � Brabender GmbH & Co. KG,Duisburg, Germany

� Dynamic rheology � RheoStress RS 1, GebruderHaake GmbH, Karlsruhe, Germany

� Scanning electron microscopy - JEOL JEE-400, Tokyo, Japan,

� X-ray diffraction - Phillips type X�pert diffractometer,0.154 nm CuKa radiation,

� DSC study - DSC-2 calorimeter, produced in the Department of Physics, University of Agriculture, Krakow, Poland,

� NMR study � impulse spectrometer - WLElectronic, Poznan, Poland

Properties of studied starches in plant gum solutions

Starch variety

Total P a)

[mg/100g]

Dry residueb

[%]

Amylosec

[%]Lipidsd

[%]Aqueous

solubility e[% dry res.]

at 80oC

Aqueoussolubility e[% dry res.]

at 90oC

Potato 125.35±0.2 85.45±0.05 24.03±0.23 0.09±0.04 12.88±0.25 18.26±0.44

Tapioca 27.29±0.27 86.85±0.04 21.42±0.03 0.12±0.00 34.9±0.76 44.19±1.53

Corn 37.9±0.66 86.24±0.04 20.72±0.06 0.40±0.08 4.86±0.10 4.28±0.06

Oat 76.7±0.56 89.09±0.02 11.88±0.09 1.23±0.00 2.6±0.28 4.2±0.14

a) According to Marsh (1959).b) According to Polish Standards PN-EN ISO (2000).c) According to Morrison & Laignelet (1983).d) According to Richter, Augustat & Schierbaum, (1969).e) According to Leach (1959).

Average molecular weight and polydispersityof starches

Polysaccahride Weight averagemolecular weight

x 107 [g/mole] (Mw)

Number averagemolecular weight

x 105 [g/mole] (Mn)

Polydispersity(Pd)

Tapioca 1.25 4.86 24.49

Corn 1.20 1.63 75.00

Oat 1.10 1.95 57.89

Potato 1.18 5.65 21.05

Average molecular weight and polydispersityof gums

Polysaccahride Weight averagemolecular weight

x 107 [g/mole] (Mw)

Number averagemolecular weight

x 105[g/mole] (Mn)

Polydispersity(Pd)

Arabic 1.99 81.2 2.45

Carob 1.65 39.1 7.21

κ-Carrageenan 0.83 7.9 11.00

Guar 0.42 4.52 9.78

Karaya 0.053 0.015 339.70

Xanthan 1.36 14.0 9.70

Pasting characteristics of potato starchwith and without chosen hydrocolloids

0

1000

2000

3000

4000

5000

6000

0 20 40 60 80 100

time [min]

visc

osi

ty [

BU

]

0102030405060708090100

tem

per

atu

re [

oC

]

potato starch 5% potato starch 4,8% + guar gum 0,2%potato starch 4,8% + carrageenan 0,2% potato starch 4,8% + xanthan gum 0,2%potato starch 4,8% + arabic gum 0,2% potato starch 4,8% + karaya gum 0,2%potato starch 4,8% + LBG 0,2% temperature profile

Pasting characteristics of tapioca starchwith and without chosen hydrocolloids

0

200

400

600

800

1000

1200

1400

1600

1800

0 20 40 60 80 100time [min]

visc

osity

[BU

]

0102030405060708090100

tem

pera

ture

[oC

]

tapioca starch 5% tapioca starch 4,8% +guar gum 0,2%tapioca starch 4,8% + carrageenan 0,2% tapioca starch 4,8% + xanthan gum 0,2%tapioca starch 4,8% + LBG 0,2% tapioca starch 4,8% + arabic gum 0,2%tapioca starch 4,8% + karaya gum 0,2% temperature profile

Pasting characteristics of corn starchwith and without chosen hydrocolloids

0

500

1000

1500

2000

2500

0 20 40 60 80 100

time [min]

visc

osity

[BU]

0

10

20

30

40

50

60

70

80

90

100

tem

pera

ture

[o C

]

CS 5% CS 4,8% + GG 0,2% CS 4,8% + CAR 0,2% CS 4,8% + GX 0,2%

CS 4,8% + GA 0,2% CS 4,8% + MCS 0,2% CS 4,8% + GK 0,2% temperature profile

Pasting characteristics of oat starch withand without chosen hydrocolloids

0

500

1000

1500

2000

2500

3000

0 20 40 60 80 100

time [min]

visc

osity

[BU]

0

10

20

30

40

50

60

70

80

90

100

tem

pera

ture

[o C]

OS 5% OS 4,8% + GG 0,2% OS 4,8% + CAR 0,2% OS 4,8% + GX 0,2%

OS 4,8% + GK 0,2% OS 4,8% + MCS 0,2% OS 4,8% + GA 0,2% temperature profile

Conclusions � pastingcharacteristics

� In potato starch aqueous systems � LBG, guar, and karaya gums increase pastingcharacteristics,

� In tapioca starch aqueous systems � LBG, guar, karaya, xanthan gums and carrageenan increase pasting characteristics,

� In corn starch aqueous systems � LBG, guar, karaya and xanthan gums increase pastingcharacteristics,

� In oat starch aqueous systems � LBG, guar, karaya and Arabic gums increase pastingcharacteristics,

Changes of moduli in 5% potato starch paste with hydrocolloids during 24 hours

0

20

40

60

80

100

120

140

160

0 4 8 12 16 20 24

Time (h)

G',G

'' (P

a)

PS - G' (PS + LBG) - G' (PS + LBG) - G''(PS + GA) - G' (PS + GA) - G'' (PS + GG) - G'(PS + GG) - G'' (PS + GK) - G' (PS + GK) - G''(PS + GX) - G' (PS + GX) - G'' (PS + CAR) - G'(PS + CAR) - G'' PS - G''

Tg delta changes of potato starch pasteswith selected hydrocolloids during 24 h

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

0 4 8 12 16 20 24

Time (h)

tan δ

(-)

PS (PS + LBG) (PS + GA) (PS + GG)(PS + GK) (PS + GX) (PS + CAR)

Changes of moduli in 5% tapioca starch paste with hydrocolloids during 24 hours

0

5

10

15

20

25

30

0 4 8 12 16 20 24

Time (h)

G',

G''

(Pa)

(TS + LBG) - G' (TS + LBG) - G'' (TS + GG) - G'(TS + GG) - G'' (TS + GA) - G' (TS + GA) - G''(TS + GK) - G' (TS + GK) - G'' (TS + CAR) - G'(TS + CAR) - G'' (TS + GX) - G' (TS + GX) - G''TS - G' TS - G''

Tg delta changes of tapioca starch pasteswith selected hydrocolloids during 24 h

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

0 4 8 12 16 20 24

Time (h)

tan δ

(-)

(TS + LBG) (TS + GG) (TS + GA) (TS + GK)

(TS + CAR) (TS + GX) TS

Changes of moduli in 5% corn starch paste with hydrocolloids during 24 hours

0

50

100

150

200

250

0 4 8 12 16 20 24

Time (h)

G',

G'' (

Pa)

300

350

(CS + LBG) - G' (CS + LBG) - G'' (CS + GG) - G'(CS + GG) - G'' (CS + GA) - G' (CS + GA) - G''(CS + GK) - G' (CS + GK) - G'' (CS + GX) - G'(CS + GX) - G'' (CS + CAR) - G' (CS + CAR) - G''CS - G' CS - G''

Tg delta changes of corn starch pasteswith selected hydrocolloids during 24 h

0

0,05

0,1

0,15

0,2

0,25

0,3

0 4 8 12 16 20 24

Time (h)

tan δ

(-)

(CS + LBG) (CS + GG) (CS + GA) (CS + GK) (CS + GX) (CS + CAR) (CS)

Changes of moduli in 5% oat starch paste with hydrocolloids during 24 hours

0

50

100

150

200

250

0 4 8 12 16 20 24

Time (h)

G',

G''

(Pa)

(OS + LBG) - G' (OS + LBG) - G'' (OS + GG) - G' (OS + GG) - (OS + GA) - G' (OS + GA) - G'' (OS + GK) - G' (OS + GK) - G(OS + GX) - G' (OS + GX) - G'' (OS + CAR) - G' (OS + CAR) OS - G' OS - G''

Tg delta changes of oat starch pasteswith selected hydrocolloids during 24 h

0

0,05

0,1

0,15

0,2

0,25

0,3

0 4 8 12 16 20 24

Time (h)

tan δ

(-)

(OS + LBG) (OS + GG) (OS + GA) (OS + GK) (OS + GX) (OS + CAR) (OS)

Conclusions � dynamic rheology

� In tapioca, corn and oat starches combined withgums � viscoelasticity of composites increasedwith time.

� In corn starch systems � an addition of almost allgums, but Arabic, decreased viscoelasticity ofcomposites, as compared to pure starch.

� In the systems consisting of tapioca and potatostarches � an addition of xanthan gum increasedviscoelasticity of composites, as compared to pure starches.

SEM

� Potato starch � Potato starch + guargum

SEM

� Potato starch + karaya gum

� Potato starch + Arabicgum

Conclusion SEM

Potato starch - guar gum, karaya and Arabicgum systems probably form separatedgel networks.

X-ray powder diffraction

� The operation setting for thediffractometer was 30 mA and 40 kV. The spectra over the range of 5.0 - 60.0o

2 theta were recorded, at the scan rate of0.02 [2 theta/s].

X-ray powder diffractionDiffractogram of xanthan gum

0200400600800

4 24 44 64angle [2 theta]

inte

nsity

Diffractogram of untreated potato starch

0

500

1000

4 24 44 64

angle [2 theta]in

tens

ity

Holder

0200400600800

4 24 44 64

angle [2 theta]

inte

nsity

Diffractogram of gelled potato starch

0

500

1000

4 24 44 64

angle [2 theta]

inte

nsity

Diffractogram of potato starch - xanthan gum blend after gelation

-200

300

800

4 24 44 64angle [2 theta]

inte

nsity

Diffractogram of potato starch - xanthan gum blend after 7 hours

0

500

1000

4 24 44 64

angle [2 theta]

inte

nsity

ConclusionsX-ray

1. Blending of starches with hydrocolloidsgenerally do not produce crystallinestructures.

2. The only observed crystalline structure inpotato starch � xanthan gum systemsdisappeared after several hours � reason(?) � probably competition for watermolecules, won by gelled, amorphicstarch.

DSC � potato starchStudiedsystem

To[oC]

Tp[oC]

Tk[oC]

ΔHm[J/mg]

PS 61.6±0.3 63.9±0.3 66.0±0.3 16.2±0.4

PS+GA 62.6 65.0 67.3 15.8

PS+GK 62.4 64.3 66.7 16.6

PS+LBG 62.5 64.4 66.8 16.1

PS+CAR 63.1 65.0 67.3 16.4

PS+GG 62.2 63.9 65.8 14.5

PS+GX 62.5 64.3 66.3 15.9

DSC � corn starchStudiedsystem

TooC TpoC TkoC ΔHmJ/mg

CS 65.3±0.2 67.7±0.2 70.7±0.2 11.73±0.7

CS+GA 65.8 67.9 71.4 11.2

CS+GK 65.7 68.3 71.1 12.4

CS+LBG 65.6 67.8 70.5 11.4

CS+CAR 67.1 69.3 71.5 11.0

CS+GG 65.7 68.0 70.1 11.5

CS+GX 66.6 68.9 71.0 11,1

DSC � tapioca starchStudiedsystem

TooC TpoC TkoC ΔHmJ/mg

TS 66.5±0.2 70.0±0.2 73.6±0.3 14.55±0.5

TS+GA 65.8 70.3 73.8 14.4

TS+GK 66.5 70.0 74.0 13.8

TS+LBG 65.6 70.4 75.6 15.5

TS+CAR 67.8 72.0 75.8 14.2

TS+GG 66.8 70.3 73.8 14.8

TS+GX 67.6 71.4 74.3 13.9

DSC � oat starchStudiedsystem

TooC TpoC TkoC ΔHmJ/mg

OS 57.8±0.26 60.6±0.2 62.7±0.3 8.9±0.2

OS+GA 57.3 60.0 62.5 8.3

OS+GK 58.1 60.9 64.3 9.1

OS+ LBG 57.7 60.7 63.4 8.8

OS+CAR 59.6 63.0 65.8 9.5

OS+GX 60.3 62.5 64.8 8.3

OS+GG 57.2 60.3 63.1 7.6

Conclusions DSC

� In almost all studied systems a small shift of DSC peakinto the range of higher temperatures was observed. The biggest increase of onset temperature was observed in the systems containing all starches withcarrageenan, as well as with xanthan gum.

� The shapes of DSC peaks differentiated to the smallextent. Only the peak of tapioca starch was significantly wider.

H1 NMR study

� Relaxation time spin-lattice (T1) and spin-spin (T2) was measured by the use of impulse spectrometer H1 NMR (WLElectronic, Poznan, Poland), at 30 MHz, equipped with temperature control system (Bruker B-VT-1000, Wissembourg, France).

Spin � lattice, T1, and spin � spin, T2, relaxation times in aqueous suspensions of potato starch

with Arabic gum.

T [0C]

20 30 40 50 60 70 80 90

T1 [ms]

T2 [ms]

1000

2000

3000

4000

5000

6000

7000

8000

T [0C]

20 30 40 50 60 70 80 90

T1 [ms]

T2 [ms]

0

1000

2000

3000

4000

5000

6000

7000

8000

T1

T2

T1

T2T2

T2

T1

T1

Pure starch gel

Starch with Arabic gum gel

Pure starch gel

Starch with Arabic gum gel

ConclusionsH1 NMR

� Gelation of starch in aqueous gum solution first involves conformational changes in polysaccharides. They proceed until temperature of gelation is achieved. After that, formation of polymeric network takes place.

� The course of gelation is controlled by water availability. The latter depends not only on the ability of particular gums to hold water molecules, but also on their conformational changes and inhibition of gelation, resulting from the interactions between gums and starch granules.

Final conclusions1. If starch is anionic (e.g. potato starch) the plant gum

partner should be non-ionic unless the partnering plant gum has low Mn and/or high polydispersity (e.g.karaya gum). Low Mn of the gum facilitates achieving thermodynamic compatibility with starch.

2. Non-ionic starches (tapioca, corn, and oat starches) combine with gums regardless they are anionic or neutral.

3. In case of both tuber starches (e.g. potato, tapioca), availability of water at temperature of beginning ofgelation (onset temperature, To) is crucial for swelling starch granules.

Thank you for your attention