Effect of melt-processing and ultrasonic treatment on physical properties of high-amylose maize starch.
High-amylose maize starch (Hylon VII) was submitted to melt-processing in an internal mixer at 100 degrees C and 40 rpm for 8 min. Glycerol was used as a plasticiser at different polymer/glycerol ratios. Torque and temperature curves were obtained. After glycerol extraction with ethyl alcohol, the samples were dispersed at 5 g/L, and treated by ultrasound radiation at the same conditions for 30 min. Samples were characterised by (1)H NMR spectrometry, viscosity measurements, and X-ray diffractometry. The results revealed that both glycerol and water had an important role on the crystallinity properties of the resulting products. Melt-processed and sonicated samples showed similar (1)H NMR spectra. Ultrasound treatment caused a significant reduction in intrinsic viscosity for the sample previously processed with the highest glycerol content, probably because of its higher solubility in water.
Lima
Felipe F
FF
Universidade Federal do Rio de Janeiro, Instituto de Macromoléculas Professora Eloisa Mano, Centro de Tecnologia, Bloco J, PO Box 68525, 21945-970 Rio de Janeiro, Brazil.
Andrade
Cristina T
CT
D000688:Amylose / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry; D044367:Phase Transition; D011522:Protons; D013696:Temperature; D014465:Ultrasonics; D014783:Viscosity; D014961:X-Ray Diffraction; D003313:Zea mays / Q000737:chemistry*
D011522:Protons; D000688:Amylose; D005990:Glycerol