Cutting into pieces
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Dissolving in mixture of CaCl2/ethanol/H2O (1:2:8 mole) at 100 °C
(ratio of silk cocoon : mixture = 2:100)
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Dialysis in distilled water for 2 nights
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Centrifugation for supernatant
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Freeze-drying
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Grinding into fine powder
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Water-soluble silk protein powder