Measurements of Starch Content in Cassava

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Measurements of Starch Content in Cassava

• Presented by Surachai Sungzikaw
• ?????? ????????????
• Workshop on Metrology in Food Safety,
  Agricultural Products and Product Safety,
  Hangzhou, PR China, June 2-6, 2008

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Overview

• About Cassava
• The Determination of Starch Content in Cassavas
  for Trade in Thailand
• A Comparison of Starch Content Values Measured by
  Reimann Balance and Electronic Balance
• A Comparison of Different Methods for Estimating
  Starch Content of Cassava Tubers between
• - Underwater Method and
• - Determination of Dry Matter by Oven
  Method

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What is Cassava?

• Cassavas are cultivated in most equatorial
  regions.

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What is Cassava? (continuous)

• Cassava tubers are long and tapered

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What is Cassava? (continuous)

• Cassava tubers are very rich in starch.

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Cassava Names Cassava Names
Indonesia Ubi kettellaKaspe
South America ManiocaYuccaMandiocaAipim
Africa ManiocCassava
India Tapioca
Thailand Cassava
Source International Starch Institute, Science
Park Aarhus, Denmark
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Products Derived from Cassavas
Source The world cassava economy , FAO
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Determination of Starch Contentin Cassava Tubers
for Trade in Thailand

• Officially for trade, determined by Reimann
  Balances verified by Weights and Measures Bureau
• Also determined by the electronic scale in
  combination with computer-based calculations
  (under pattern testing)

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1. Determination of Starch Content by Reimann
Balance .
Weigh 5000 g clean tubers into upper basket in air
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1. Determination of Starch Content by Reimann
Balance .
Weigh 5000 g clean tubers in the upper basket in
air
Move the tubers into the lower basket under water
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1. Determination of Starch Content by Reimann
Balance .
Weigh 5000 g clean tubers into upper basket in air
Move the tubers into the lower basket under water
Weigh the tubers again in water
Determine of Starch Content
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2. Determination of Starch Content by the
electronic scale in combination with
computer-based calculations
Source Genius Design Engineering Co.,Ltd.
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The Construction of the scale

1. Indicating Device
2. Load Cell
3. Basket (load-receiving element)
4. Water Bucket
5. Hydraulic Lift

Source Genius Design Engineering Co.,Ltd.
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Measuring Procedure for Determination of Starch
Content
With clean water, lift the bucket to the empty
basket until the basket is completely immersed in
water.
Weigh the empty basket immersed in water and
record the weight of basket by the indicating
device.
Move the bucket back to the lower position.
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Measuring Procedure for Determination of Starch
Content
Weigh 3-6 kg clean cassava tubers into the basket
in air.
Lift the bucket to the basket containing cassava
tubers until the basket is completely immersed in
water and weigh again.
Starch content of the sampling is calculated by a
microprocessor in the indicating device.
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Comparison of Starch Content Values Measured by
Reimann Balance and the Electronic Balance

• 1
• Measuring by Reimann Balance

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Comparison of Starch Content Values Measured by
Reimann Balance and Electronic Balance

• 2
• Measuring by
• the electronic balance

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Samples
Sample No. Varieties Places
1 KU50 North-East
2 Kan Deang North-East
3 KU50 North-East
4 Kan Deang North-East
5 Rayong 90 North-East
6 KU50 East
7 KU50 East
8 Rayong 90 East
9 Rayong 90 East
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The procedure

• Calibrated the Reimann Balance and electronic
  balance with class M1 standard mass
• Programmed in the Computer of The Electronic
  Balance to calculate starch content by the
  following equation

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The procedure (continuous)

• Wo weight of the cassava sample in air
• Wu weight of the sample under water
• SG specific gravity
• BC basket compensated weight
• ( BC weight in air weight under
  water)

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• First determined starch content of 5 kg, 3 kg,
  and 1 kg wet clean tubers by Reimann Balance
• Second determined starch content of the same
  samples by the Electronic Balance

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Results
Sample Sample Starch Content Values Starch Content Values
No. Sizes Reimann Electronic
1 5 kg 21.2 21.11
  3 kg 21.1 21.04
  1 kg 21.1 21.12
2 5 kg 26.7 26.59
  3 kg 26.3 26.54
  1 kg 26.3 26.06
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Discussion

• Baskets weight compensation for the Electronic
  Balance is significance for measurement of
  specific gravity by Under Water Weight method
• Specification of the basket comprised with the
  Electronic Balance have to be considered

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• With the determination of cassava tubers by the
  Electronic Balance, there is no significant
  difference on the starch content values of by
  decreasing each sampling weight to 1000 g. from
  5000 g.

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A Comparison of Different Methods for Estimating
Starch Content in Cassava Tubers
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Objective

• To revise the correlation equation between
  specific gravity and starch content of cassava
  tubers
• To obtain the information for developing the
  Electronic Balances

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Methods of Determination of Starch Content

• Under Water Weight Method
• Determination of Dry Matter by Oven at 130 ?C

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The Experiments

• The experiments were carried out to determine
  starch contents in the same samples by Under
  Water Weight method and by Oven method at 130 ?C

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Apparatus

• For Under Water Weight method
• Analytical balance weighing to the nearest 0.01 g
  
• Vessel with clean water
• Stainless steel wire for hanging the sample
  weighed in water

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Apparatus (continue)

• For the Determination of Dry Matter by Oven
  Method
• Analytical balance weighing to the nearest 0.1 mg
• Dishes of aluminum with tight-fitting lids
• Electrically heated oven
• Desiccator containing an effective desiccant

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The Procedure

• Determined of specific gravity of cassava tubers
  by Under Water Weight method
• Calculated starch content values with the
  following equation
• Starch Content (SG
  1.00906)/0.004845

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• Determined of dry matter of cassava tubers by
  Oven at 130 ?C
• Calculated starch content values with the
  empirical equation published by FAO as follow
• Percent Starch Content Percent Total Dry
  Matter 7.3

Source 1. ISI 01-1e Determination of Dry Matter
in Starch by Oven Drying at 130 oC, International
Starch Institute, Science Park Aarhus, Denmark
2. Cassava processing, FAO
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Comparison
Under Water Weight Under Water Weight Oven at 130 C Oven at 130 C D
SG Starch Dry Matter Starch Starch
1.092 17.1 30.7 23.4 6.3
1.097 18.2 34.1 26.8 8.6
1.103 19.3 35.5 28.2 8.9
1.106 20.1 35.5 28.2 8.1
1.111 21.1 37.6 30.3 9.2
1.118 22.5 35.7 28.4 5.9
1.125 23.9 36.8 29.5 5.6
1.128 24.6 38.1 30.8 6.2
1.136 26.3 39.0 31.7 5.4
1.145 28.0 40.5 33.2 5.2
1.152 29.5 43.2 35.9 6.4
1.152 29.5 43.2 35.9 6.4
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Discussion

• The starch content values estimated by UWW method
  are significant different from by Oven method
• To confirm this, other reliable methods are
  required to make more comparison such as Krochmal
  and Kilbride or Near Infrared Reflectance (NIR)
• The correlation equation between specific gravity
  and starch content of cassava tubers should be
  revised

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Thank You for Your Attention
A cassava field in Chonburi, Thailand