THESIS

2. X Ray Diffraction Measurement
2.1 Apparatus
2.1.1 Wide-angle X-ray diffractometer (JEOL,JDX 3530, Japan).
2.1.2 Silicon sample cell
2.1.3 Computer with program MDI Jade 6.5 (Japan)
2.2 Procedure for Sample Preparation
X Ray Diffraction pattern of native rice starch and RS III samples were
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examined according to Cheetham and Tao (1998).Take a samples for about 5 g. Pack
tightly in rectangular silicon cell and spread samples evenly to obtain a smooth
surface and place the sample cell in sample holder. Expose to the X-ray beam.
The X-ray diffractometric conditions as following Cairns et al., (1997
Monochromatic Cu-K2 radiation 0.154 nm
X-ray generator power 300 mA, 30 kB
Scanning, 2-theta 10 o to 70.0 o
Step angle 0.05 o
Count time 2 sec
Measurement temperature ambient temperature
2.3 Crystallinity calculation
Amorphous and crystalline sections were examined from the X-ray
diffractograms (Appendix Figure B 2). Peak baseline (white area) and smooth curve
(bold area) were computer-plotted on the diffractogram (Appendix Figure B 3). The
area above the smooth curve was the crystalline portion and the bold area above the
peak baseline was the amorphous portion. The % crystallinity of RS III samples were
calculated as the ratio of area of the crystalline sharp peak over the total area at angles
between 10 and 45 o 2θ using a computer program based on the methods of Nara et al.
(1978).