Physicochemical and pharmaceutical properties of carboxymethyl rice starches modified from native starches with different amylose content

• Main Authors: Kittipongpatana O.S., Chaitep W., Kittipongpatana N., Laenger R., Sriroth K.
• Format: Article
• Language: English
• Published: 2014
• Online Access: http://www.scopus.com/inward/record.url?eid=2-s2.0-34547903584&partnerID=40&md5=52e7edc845e80be5f7c72835d34bde31; http://cmuir.cmu.ac.th/handle/6653943832/4449
• Institution: Chiang Mai University

Carboxymethyl rice starches (CMRS) were prepared from nine strains of native rice starches with amylose contents of 14.7-29.1%. The reaction was conducted at 50°C for 120 min using monochloroacetic acid as a reagent under alkaline conditions and 1-propanol as a solvent. After determining the degree of substitution (DS), the physicochemical properties including water solubility, pH, and viscosity of 1% (w/v) solution, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses of the granules, as well as some pharmaceutical properties of CMRS powders and pastes were investigated. The DS range was 0.25-0.40. All CMRS dissolved in unheated water and formed viscous gel. A good positive correlation was observed between amylose content and DS (r = 0.9278) but not viscosity. SEM and XRD concurrently revealed significant physical alteration of CMRS granules compared with those of native starches, which reflected the changes in the properties of CMRS. At 3% (w/w), CMRS can function as tablet binder in the wet granulation of both water-soluble and water-insoluble diluents. The tablets compressed from these granules showed good hardness with fewer capping problems compared with those prepared using the pregelatinized native rice starch as a binder. In addition, most CMRS pastes formed clear films with varying film characteristics, depending upon the amylose content of the native starches. This type of modified rice starch can potentially be employed as a tablet binder and film-former for pharmaceutical dosage formulations. © 2007 AACC International, Inc.