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International Starch Institute
Science Park Aarhus, Denmark
ISI 32-1e Determination of Starch Size Distribution by Screening

1. Scope The method is applicable to starch

 

LT 1970
Rev. LT 7 Feb1999
2. Principle Starch size distribution is determined by screening

 

3. Apparatus 3.1 Screening set of lit, one or more screens and bottom
3.2 Laboratory scale
4. Procedure Weigh TARA of each screen and bottom
Weigh 100 g starch sample and transfer to top screen.
Shake stack of screens until fines through top screen is negligible.
Remove top screen and shake until fines through next screen are negligible and so on until all screens are removed.
Weigh TOTAL of each screen and bottom

 

5. Calculation NETTO = TOTAL - TARA of each screen and bottom
GRAND NETTO = Sum of individual NETTO
Report with one decimal each starch fraction as percent of GRAND TOTAL and characterised by the trapping mesh width (opening) in micrometer.
Example:
0 % > 250 m
0.1% > 125 m, (< 250 m)
2.1% > 63 m, (< 125 m)
98.2 % < 63 m

 

Mesh width in parenthesis may be omitted if it is obvious that fractions are not accumulated
6. Notes Preferably use a 200 mm dim. vibrator sieve shaker and shake for 15 min.
The following sizes belongs to an ISO main serie:
Screen Conversion Table
DIN 4188 equivalent ASTM
0.063 mm 230 mesh
0.071 mm 200 mesh
0.125 mm 120 mesh
0.180 mm 80 mesh
0.250 mm 60 mesh
0.355 mm 45 mesh
7. Image

seiveshaker.gif (12819 bytes)

Sieve shaker

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Keywords: laboratory method determination screening granule size screen sieve starch