Measurements of Starch Measurements of Starch Content in CassavaContent in Cassava

Presented: by Surachai SungzikawPresented: by Surachai Sungzikaw

สุ�รชั�ย สุ�งข์ศร�แก้�วสุ�รชั�ย สุ�งข์ศร�แก้�ว

Workshop on Metrology in Food Safety, Agricultural Workshop on Metrology in Food Safety, Agricultural Products and Product Safety, Hangzhou, PR China, Products and Product Safety, Hangzhou, PR China,

June 2-6, 2008June 2-6, 2008

OverviewOverview

1.1. About CassavaAbout Cassava

2.2. The Determination of Starch Content in The Determination of Starch Content in Cassavas for Trade in ThailandCassavas for Trade in Thailand

3.3. A Comparison of Starch Content Values A Comparison of Starch Content Values Measured by Reimann Balance and Electronic Measured by Reimann Balance and Electronic BalanceBalance

4 . A Comparison of Different Methods for Estimatin g Starch Content of Cassava Tubers between:

- Underwater Method and - Determination of Dry Matter by Oven Method

What is Cassava?What is Cassava?

Cassavas are Cassavas are cultivated in most cultivated in most equatorial regions.equatorial regions.

What is Cassava? (continuous)What is Cassava? (continuous)

Cassava tubers are Cassava tubers are long and taperedlong and tapered

What is Cassava? (continuous)What is Cassava? (continuous)

Cassava tubers are Cassava tubers are very rich in starch.very rich in starch.

Cassava NamesIndonesia Ubi kettella

KaspeSouth America Manioca

YuccaMandiocaAipim

Africa ManiocCassava

India TapiocaThailand CassavaSource: International Starch Institute, Science Park Aarhus, Denmark

Products Derived from CassavasProducts Derived from Cassavas

Source: The world cassava economy , FAO

Determination of Starch ContentDetermination of Starch Contentin Cassava Tubers for Trade in Cassava Tubers for Trade

in Thailandin Thailand

Officially for trade, Officially for trade, determined by determined by Reimann BalancesReimann Balances verified by Weights verified by Weights and Measures Bureauand Measures Bureau

Also determined by Also determined by the electronic scale in the electronic scale in combination with combination with computer-based computer-based calculationscalculations

(under pattern testing)(under pattern testing)

1. Determination of Starch Content by Reimann Balance1. Determination of Starch Content by Reimann Balance

..

Weigh 5000 g clean tubers into upper

basket in air

Weigh 5000 g clean tubers in the upper

basket in air

Move the tubers into the lower basket under water

1. Determination of Starch Content by Reimann Balance1. Determination of Starch Content by Reimann Balance

..

Weigh 5000 g clean tubers into upper

basket in air

Weigh the tubers again in water

Determine of Starch Content

Move the tubers into the lower basket under water

1. Determination of Starch Content by Reimann Balance1. Determination of Starch Content by Reimann Balance

..

2. Determination of Starch Content by the electronic 2. Determination of Starch Content by the electronic scale in combination with computer-based calculations scale in combination with computer-based calculations

Source: Genius Design & Engineering Co.,Ltd.

1.1. Indicating DeviceIndicating Device

2.2. Load CellLoad Cell

3.3. Basket (load‑receiving Basket (load‑receiving element)element)

4.4. Water Bucket Water Bucket

5.5. Hydraulic LiftHydraulic Lift

The Construction of the scaleThe Construction of the scale

Source: Genius Design & Engineering Co.,Ltd.

Measuring Procedure for Determination of Starch ContentMeasuring 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.

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.

Measuring Procedure for Determination of Starch ContentMeasuring Procedure for Determination of Starch Content

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

11

Measuring by Reimann BalanceMeasuring by Reimann Balance

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

22

Measuring by Measuring by

the electronic balance the electronic balance

SamplesSamplesSample Sample

No.No.VarietiesVarieties PlacesPlaces

11 KU50KU50 North-EastNorth-East

22 Kan DeangKan Deang North-EastNorth-East

33 KU50KU50 North-EastNorth-East

44 Kan DeangKan Deang North-EastNorth-East

55 Rayong 90Rayong 90 North-EastNorth-East

66 KU50KU50 EastEast

77 KU50KU50 EastEast

88 Rayong 90Rayong 90 EastEast

99 Rayong 90Rayong 90 EastEast

The procedureThe procedure

1.1. Calibrated the Reimann Balance and Calibrated the Reimann Balance and electronic balance with class Melectronic balance with class M11 standard standard massmass

2.2. Programmed in the Computer of The Programmed in the Computer of The Electronic Balance to calculate starch Electronic Balance to calculate starch content by the following equation:content by the following equation:

%0.004845

1.00906)(SGContentStarch

WWoo = weight of the cassava sample in air = weight of the cassava sample in air

WWuu = weight of the sample under water = weight of the sample under water

SG = specific gravitySG = specific gravityBC = basket compensated weight BC = basket compensated weight ( BC = weight in air – weight under water)( BC = weight in air – weight under water)

The procedureThe procedure (continuous)(continuous)

First determined starch content of 5 kg, 3 kg, and First determined starch content of 5 kg, 3 kg, and 1 kg wet clean tubers by Reimann Balance1 kg wet clean tubers by Reimann Balance

Second determined starch content of Second determined starch content of the same the same samplessamples by the Electronic Balance by the Electronic Balance

ResultsResults

Sample Sample 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

DiscussionDiscussion

Basket’s weight compensation for the Electronic Basket’s weight compensation for the Electronic BalanceBalance is significance for measurement of is significance for measurement of specific gravity by Under Water Weight methodspecific gravity by Under Water Weight method

Specification of the basket comprised with the Specification of the basket comprised with the Electronic Balance have to be consideredElectronic Balance have to be considered

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

A Comparison of Different Methods fo r Estimating

Starch Content in Cassava Tubers

ObjectiveObjective To revise the correlation To revise the correlation

equation between specific equation between specific gravity and starch content gravity and starch content of cassava tubersof cassava tubers

To obtain the information To obtain the information for developing the for developing the Electronic BalancesElectronic Balances

MethodsMethods of Determination of Starch of Determination of Starch ContentContent

1. Under Water Weight Method

2.2. Determination of Dry Matter by Oven at Determination of Dry Matter by Oven at 130 130 CC

The ExperimentsThe Experiments

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

ApparatusApparatus

For Under Water Weight methodFor Under Water Weight method• Analytical balance weighing to the Analytical balance weighing to the

nearest 0.01 g nearest 0.01 g • Vessel with clean waterVessel with clean water• Stainless steel wire for hanging the Stainless steel wire for hanging the

sample weighed in watersample weighed in water

ApparatusApparatus ((continue)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

The ProcedureThe Procedure

1.1. Determined of specific gravity of Determined of specific gravity of cassava tubers by Under Water cassava tubers by Under Water Weight methodWeight method

2.2. Calculated starch content values Calculated starch content values with the following equation:with the following equation:

Starch Content = (SG – 1.00906)/0.004845 %Starch Content = (SG – 1.00906)/0.004845 %

3.3. Determined of dry matter of cassava Determined of dry matter of cassava tubers by Oven at 130 tubers by Oven at 130 C C

4.4. Calculated starch content values with Calculated starch content values with the empirical equation published by the empirical equation published by FAO as follow:FAO as follow:

Percent Starch Content = Percent Total Dry Matter – 7.3 %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, Internati

onal Starch Institute, Science Park Aarhus, Denmark 2. Cassava processing, FAO

ComparisonComparisonUnder Water WeightUnder Water Weight Oven at 130 COven at 130 C

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

DiscussionDiscussion The starch content values estimated by UWW The starch content values estimated by UWW

method are significant different from by Oven method are significant different from by Oven methodmethod

To confirm this, other reliable methods are To confirm this, other reliable methods are required to make more comparison such as required to make more comparison such as Krochmal and Kilbride or Near Infrared Krochmal and Kilbride or Near Infrared Reflectance (NIR)Reflectance (NIR)

The correlation equation between specific gravity The correlation equation between specific gravity and starch content of cassava tubers should be and starch content of cassava tubers should be revisedrevised

Thank You for Your AttentionThank You for Your Attention

A cassava field in Chonburi, ThailandA cassava field in Chonburi, Thailand