| There are two regions in starch granular, which are crystalline and non-crystalline region. The non-crystalline region is a mainly area and water is a generally solvent for the chemical reaction of modified starch. Further reaction was limited as a result of the crystalline region. It could be improved the reactivity by reducing the crysallinity of cassava starch.To study the effect on the physic-chemistry properties of cassava starch by ultrasonic and different polarity solvents as dispersant. The physical properties, which are degree of crystallinity, viscosity curves, transparency and thermal stability of viscosity of processed cassava starches (PCS), were respectively investigated by X-ray Powder Diffraction (XRD), Digital Viscometer, UV-Visble spectrophotometer and Rotary viscometer. And the hydroxypropyl starch (HS) was synthesized by the PCS. The degree of substitution of HS as an indicator, investigated the reactivity of PCS’s starch.The major results of the study were as follows.1 The degree of PCS’s crystallinity increased in the following sequence:Acetone < Methanol< Isobutanol< Ethanol< Water< Ethyl acetate< Butanol< Cyclohexane in different solvents and Ethyl acetate and water< Cyclohexane and water< Methanol and water< Acetone and water< Butanol and water< Ethanol and water< Isobutanol and water in different solvents and distilled water.The optimal conditions of single factor were that concentration of cassava starch was 15%, the conditions of ultrasonic, which were continuous action time, intermittent time, action times, power and horn depth of ultrasonic, were respectively 7s,10s,40 times,600W and 20mm, and the proportion of distilled water and cassava starch (v:m) was 1:4 for the degree of PCS’s crystallinity. Degree of PCS’s crystallinity was about 28.2-29.8%, and its mean value was 29.1%.2 The descending order about the acceleration of PCS’s viscosity at the beginning temperature of gelatinization was Ethyl acetate> Cyclohexane> Ethanole> Isobutanol> Methanol> Acetone> Butanol> Water in different solvents and Butanol and water> Ethyl acetate and water> Acetone and water> Methanol and water> Ethanol and water> Isobutanol and water> Cyclohexane and water in different solvents with distilled water.The optimal conditions of single factor were that concentration of cassava starch was 10%, the conditions of ultrasonic were respectively 7s,5-15s,20-40 times, 400W and 10mm, and the proportion of distilled water and cassava starch (V:M) was 3:8 (88.64 mPa·s/℃2). The acceleration of PCS’s viscosity was about 36.18-38.94 mPa·s/℃2, and its mean value was 37.72 mPa·s/82 (excluding the actor of the proportion of distilled water and cassava starch).3 The transparency of PCS’s descending order was Cyclohecane> Ethanol> Acetone> Ethyl acetate> Water> Isobutanol> Methanol> Butanol in different solvents and Mthanol and water> Ethyl acetate and water> Acetone and water> Butanol and water> Isobutanol and water> Ethanol and water> Cyclohexane and water in different solvents with distilled water.The optimal conditions of single factor were that concentration of cassava starch was 15%, the conditions of ultrasonic were respectively 10s,25s,20-30 times, 500W and 15mm, and the proportion of distilled water and cassava starch (V:M) was 3:8 for the transparency. The transparency was about 44.9-49.7%, and its mean value was 46.8%.4 The thermal stability of PCS’s viscosity descending order was Cyclohexane> Ethanol> Isobutanol> Butanol> Acetone> Water> Ethyl acetate> Methanol in different solvents and Cyclohexane and water> Ethyl acetate and water> Acetone and water> Ethanol and water> Isobutanol and water> Methanol and water> Butanol and water in different solvents with distilled water.The optimal conditions of single factor were that concentration of cassava starch was 15%, the conditions of ultrasonic were respectively 7s,25s,30-50 times, 500W and 30mm, and the proportion of distilled water and cassava starch (V:M) was 1:2 for the thermal stability of PCS’s viscosity. The transparency was about 41.9-50.8%, and its mean value was 46.3%.5 The degree of HS’s substitution, which were synthesized by PCS, descending order was Water> Acetone> Ethyl acetate> Butanol> Cyclohexane> Ethanol> Isobutanol> Methanol in different solvents and Ethyl acetate and water> Ethanol and water> Cyclohexane and water> Butanol and water> Acetone and water> Isobutanol and water> Methanol and water in different solvents with distilled water.The optimal conditions of single factor were that concentration of cassava starch was 15%, the conditions of ultrasonic were respectively 10s,10s,50 times and 500W, and the proportion of distilled water and cassava starch (V:M) was 3:8 for the degree of HS’s substitution. The higher Degree of HS’s substitution was 0.131 and the degree was 0.08 for natural cassava starch.The PCS’s was reduced to 28% by ultrasonic and ethyl acetate and water as adispersant. The substitution of HS was incressed 0.051. |
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