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Quantitative Analysis of Cooked

Rice Grain Texture

Yanco Rice Quality TeamPresented by

Dr Jixun Luo

19th Jul 2017

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Introduction

Rice varieties with different quality and texture are used to

make different type of foods

Adapted from DPI website

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Introduction

Factors affecting cooked rice texture

• Amylose content

• Post-harvest processing

• Cooking methods

– South and East Asians: rice cooker, particular water ratio

– Indians: boiling in excess water

– Americans: use large amount of water then drained

Current methods (indirectly measures texture)

• RVA (setback correlated with firmness)

• Gel texture analysis (gel firmness)

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Introduction

Texture analysis

• Sensory panel

High cost for training and maintaining the panel

Not ideal for screening purpose

• Instrumental approach

Less cost and less time-consuming

• Texture analyser

Mimic the first bite of a food sample

probe

rice

scale

Firmness Stickiness

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Aims of study

• Develop a method to directly measure

cooked rice texture

• Compare textures of breeding lines and

existing varieties

• Determine the contribution of different grain

quality factors affecting the texture (amylose

content, gelatinisation temp, RVA parameters, etc.)

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Materials

30 varieties from Leeton farm, C2016

Selected based on

• Different grain dimensions

• Apparent amylose content 7~27 %

• Gelatinisation temp (GT) 65~79 oC

• Optimum cooking time 14~21 min

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Method

Cooking method

Excess water method with

• Standard cooking time

• Standard water ratio

Instrumental texture analysis• Excess water drained after cooking

• Single layer cooked rice grains

• Two cycle compression

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Method

Cooking in RVA • 1g white rice contained in tea ball

mesh and rinsed with tap water

• Add water up to 4g in a RVA can

• Seal the can with lid on using the

thermo tape

• Load on to RVA machine

• Run the standard cooking profile

• Remove the lid after cooking to release the steam

• Replace with another lid at 1 min to keep it warm for

3 min on the bench

95oC, 21min

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Method

Texture Profile Analysis (TPA) using TXT

• Weigh and prepare 1g cooked rice sample

within the mark on a glass plate in 1 min

• Run the standard test profileTwo cycle compression,

compress to 80% sample height

Technical tips:

Each single grain sits on its side and spread

well. Sample height is negatively correlated with

firmness for the same sample.

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Results - theory

(Firmness)

Peak force

Area3

(Stickiness)

Cycle 1 Cycle 2

Area4

(Ration of

Area3 and 4 is

cohesiveness)

Texture Profile

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Results - Firmness

0

1000

2000

3000

4000

5000

b

f

bc

g

a

7%~9% 17%~21% 25%~27%

b

d de

d

f

d ddcc

ff

ccb b

cd

cb

d

f

contro

l

Fir

mn

ess

(g

)

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Results - Firmness

Calmochi101TDK11

HMN

Tarra140

YRW4

Reiziq

YRM69

Quest

Koshi

Nipponbare

IRAT109

Doongara

IR64

L205

Fin

SHZ2

BD192

Amber33

Viet5

Amarroo

Namaga

Opus

Langi

Bengal

Jarrah

KyeemaYRB4

TakanriCalmochi 201

YRM70

2000

2500

3000

3500

4000

4500

65 70 75 80

7%~9%

17%~21%

25%~27%

Amylose

content

Gelatinization Temp (oC)

Fir

mn

ess

(J)

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Results - Firmness

y = 77.459x + 2027

R² = 0.76640

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 5 10 15 20 25 30

Fir

mn

ess

(g

)

Amylose content (%)

y = 3.2828x + 3020.5

R² = 0.4789

2000

2500

3000

3500

4000

4500

5000

0 100 200 300 400 500

Fir

mn

ess

(g

)

Gel firmness (g)

None Waxy

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Results - Stickiness

0

20

40

60

80

100

120

140

160

180

200

aa

bb b

bb

b

cc cc ccc

c cd

de e

ff

fgg

g

h h

contro

l7%~9% 17%~21% 25%~27%

Sti

ckin

ess

(J)

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Results - Stickiness

Calmochi101

TDK11

HMN

Tarra140

YRW4

Reiziq

YRM69

Quest

Koshi

Nipponbare

IRAT109

Doongara

IR64

L205

Fin

SHZ2

BD192Amber33

Viet5

Amarroo

Namaga

Opus

Langi

Bengal

Jarrah

Kyeema

YRB4

Takanari

Calmochi 201

YRM70

0

20

40

60

80

100

120

140

160

180

65 70 75 80

7%~9%

17%~21%

25%~27%

Amylose

content

Sti

ckin

ess

(J)

Gelatinization Temp (oC)

Name of program

Results - Stickiness

Calmochi101

TDK11

HMN

Tarra140

YRW4

Reiziq

YRM69

Quest

Koshi

Nipponbare

IRAT109

Doongara

IR64

L205

Fin

SHZ2

BD192 Amber33

Viet5

AmarrooNamaga

Opus

Langi

Bengal

Jarrah

Kyeema

YRB4

Takanari

Calmochi 201

YRM70

y = -0.0505x + 274.95

R² = 0.4697

0

20

40

60

80

100

120

140

160

180

2000 2500 3000 3500 4000 4500 5000

Sti

ckin

ess

(J)

Firmness (g)

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Results - Stickiness

y = 13.949x - 171.71

R² = 0.5255

0

20

40

60

80

100

120

140

160

12 14 16 18 20 22 24

Sti

ckin

ess

(J)

OCT (oC)

None Waxy

y = -13.129x + 1146.2

R² = 0.7708

-1500

-1000

-500

0

500

1000

1500

0 50 100 150 200

Se

tba

ck (

RV

AU

)

Stickiness (J)

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Summary

• Used TVT machine to measure texture

directly

• Compared results to gel firmness

• Explored texture correlation with OCT, GT,

RVA setback parameter

• The outlier varieties in the texture profile

of each amylose group were found

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Future work

• More quality data for covariant analysis

• Amylose & amylopectin structure analysis

by CE/SEC

• Look at the outliers

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Acknowledgement

Rice Quality Team:

Dr Rachelle Ward Dr Laura Pallas

Ms Margrit Martin Dr Prakash Oli

Ms Leanne Johnston Ms Yuki Sims

Ms Kylie Elliott Dr Mark Talbot

Ms Rachael Wood (PhD candidate)

Rice Breeding Team:

Dr Peter Snell

Dr Ben Ovenden

Supervisor:

Dr Sandra McDougall