The physicochemical properties of a spray dried glutinous rice starch biopolymer

Colloids and Surfaces B:Biointerfaces 78 (2010) 30–35

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Colloids and Surfaces B:

Biointerfaces

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /c o l s u r f

b

The physicochemical properties of a spray dried glutinous rice starch biopolymer

Pornpun Laovachirasuwan a ,Jomjai Peerapattana a ,Voranuch Srijesdaruk b ,Padungkwan Chitropas a ,Makoto Otsuka c ,∗

a

Department of Pharmaceutical Technology,Faculty of Pharmaceutical Sciences,Khon Kaen University,Khon Kaen 40002,Thailand b

Department of Food Technology,Faculty of Technology,Khon Kaen University,Khon Kaen 40002,Thailand c

Department of Pharmaceutical Technology,Research Institute of Pharmaceutical Sciences,Musashino University,Shinmachi 1-1-20,Nishi-Tokyo 202-8585,Japan

a r t i c l e i n f o Article history:

Received 30December 2009

Received in revised form 31January 2010Accepted 4February 2010

Available online 11 February 2010Keywords:

Glutinous rice starch

Spray dried glutinous rice starch Biopolymer

Scanning Electron Microscopy X-ray Diffraction

Differential Scanning Calorimetry

a b s t r a c t

Glutinous rice starch (GRS)is a biopolymer used widely in the food industry but not at all in the pharma-ceutical industry.There are several ways to modify this biopolymer.Physical modification is simple and cheap because it requires no chemicals or biological agents.The aim of this study was to characterize the physicochemical properties of a spray dried glutinous rice starch (SGRS)produced from pregelatinized GRS.The surface morphology changed from an irregular to concave spherical shape as revealed by Scan-ning Electron Microscopy (SEM).SGRS was almost amorphous as determined by X-ray Diffraction (XRD)spectroscopy.The water molecules became linked through hydrogen bonds to the exposed hydroxyl group of amorphous SGRS as determined by Near Infrared (NIR)spectroscopy.Then,SGRS formed a colloid gel matrix with water and developed a highly viscous gelatinous form as determined using Dif-ferential Scanning Calorimetry (DSC)and a stress control type rheometer.In addition,SGRS can swell and produce a gelatinous surface barrier like a hydrophilic matrix biopolymer which controls drug release.Therefore,a novel application of SGRS is as a sustained release modifier for direct compression tablets in the pharmaceutical industry.

© 2010 Elsevier B.V. All rights reserved.

1.Introduction

Glutinous rice starch (GRS)is a natural biopolymer used widely in the food industry but not at all in the pharmaceutical indus-try.Its major constituents are very simple substances composed of glucose-linked residues.First,amylose is amorphous in native starch and composed of essentially linear chains of ␣-1,4linked glucose units.It can contain approximately 200–2000anhydroglu-cose units.Aqueous solutions of amylose are very unstable due to intermolecular attraction and the association of neighboring amy-lose molecules.This leads to retrogradation.Second,amylopectin is a semi-crystalline highly branched polysaccharide with an ␣-1,4backbone and ␣-1,6branch points.Each branch contains about 20–30anhydroglucose units.Aqueous solutions of amylopectin are characterized by high viscosity,clarity,and stability as measured by resistance to gelling on aging [1,2].The highest amylopectin content has the highest swelling power [3,4].

Although native starch has been widely used in food process-ing,the physical properties of these starches and the colloidal sols produced from them are limited in terms of the commercial appli-cations for which they are suited.For example,native rice starches are limited in their applications due to their instability under var-

∗Corresponding author.Tel.:+81424688658;fax:+81424688658.E-mail address:motsuka@musashino-u.ac.jp (M.Otsuka).ious temperatures,shears,and pH conditions.Native starches are often modified to develop specific properties such as solubility,tex-ture,adhesion,and heat tolerance,so as to be suitable for industrial applications [5–11].There are many different methods of modify-ing starch biopolymers [7,12–15].

Physical modifications are simple and inexpensive,and induced colloidal level transformation,because they can be accomplished without chemicals or even biological agents.Thermally modified starch biopolymers may be used as a hydrophilic matrix for oral drug delivery.Thermally pregelatinized starches have proved suit-able for formulating hydrophilic matrix systems because their technological and physicochemical properties are rather similar to those of commonly used cellulose derivatives,i.e.hydroxypropyl-methyl cellulose [7,13,16,17].There are processing techniques that gelatinize the starch biopolymer and then recover it as a dry pow-der prior to sale to the end-user.Fully pregelatinized starches can be produced by heating the starch slurry above the gelatinization temperature and drying it using drum drying,extrusion or spray drying.The energy required for the gelatinization is proportional to the amount of native starch.The drum-drying and extruder change the product into a flaky and cylindrical thread,respectively.This method must be continued to obtain a spherically shaped product.As a controlled pregelatinized spray drying technique,the starch slurry was preheated at a fixed temperature over a certain period of time,just before entering the spray drier [16].Mitrevej et al.[18,19]reported that both flow rates and percent compressibility

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