Cassava and Starch Technology Research Unit

Bangkok, Thailand

Cassava and Starch Technology Research Unit

Bangkok, Thailand
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Sangseethong K.,Cassava and Starch Technology Research Unit | Termvejsayanon N.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University
Carbohydrate Polymers | Year: 2010

Physicochemical properties of oxidized cassava starch as influenced by different oxidizing agents (sodium hypochlorite and hydrogen peroxide) were investigated. The starch was modified under controlled temperature and pH with 3% oxidants (based on starch) between 30 and 300 min. The results showed that hypochlorite oxidation favored the formation of carboxyl group while carbonyl was the major functional group formed during peroxide oxidation. The molecular sizes determined by HPSEC and the apparent viscosity of starch were decreased to a similar extent by both oxidants; however, the changes observed in peroxide oxidation proceeded with a faster rate. Rheological measurement revealed that peroxide-oxidized starches had a higher tendency for gelation and gave a firmer gel than hypochlorite-oxidized starches. The gelatinization temperatures increased following peroxide oxidation but decreased after hypochlorite oxidation. The gelatinization enthalpy decreased after oxidation by both chemicals. Results from DSC demonstrated that amylopectin retrogradation was not significantly affected by both types of oxidation. © 2010 Elsevier Ltd. All rights reserved.


Kwon H.-J.,Seoul National University | Sunthornvarabhas J.,Seoul National University | Sunthornvarabhas J.,Cassava and Starch Technology Research Unit | Park J.-W.,Seoul National University | And 5 more authors.
Composites Part B: Engineering | Year: 2014

Kenaf fiber and corn husk flour were used as reinforcement in a novel biodegradable hybrid bio-composite system. It was investigated how the aspect ratios of kenaf fibers measured before and after passing through extrusion process influence the mechanical properties and the improvement of predicted values obtained by the Halpin-Tsai equation. It was found that considering of the aspect ratio of reinforcement obtained after the extrusion process, the difference between theoretical and experimental values of the tensile modulus was not significant, indicating that the aspect ratio determined after extrusion did not influence the predicted values. Therefore it was pointed out that the initial values of aspect ratio determined before extrusion can be used directly. It was also found that a scale ratio between reinforcements of different aspect ratios may play a role as a controlling factor in optimizing the mechanical properties of a hybrid bio-composite. © 2013 Elsevier Ltd. All rights reserved.


Sunthornvarabhas J.,Cassava and Starch Technology Research Unit | Chatakanonda P.,Kasetsart University | Piyachomkwan K.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University
Materials Letters | Year: 2011

Smoothed fibers of PLA/cassava starch were prepared by single nozzle electrospinning process intended for tissue scaffold application. PLA in dichloromethane (DCM) solution was immiscible with cassava starch in dimethylsulfoxide (DMSO) solution. A conjugated solvent system was introduced to simply prepare a well-mixed solution of both components. In this experiment, methanol was used as a conjugated solvent between PLA/DCM solution and cassava starch/DMSO solution to create well-mixed solution. Conjugated solvent selection was based on values of polarity index, intermediate between values of DCM and DMSO. Smoothed electrospun fiber of PLA/cassava starch was obtained. © 2010 Elsevier B.V. All rights reserved.


Maneewong C.,Kasetsart University | Sunthornvarabhas J.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University
Applied Mechanics and Materials | Year: 2013

Natural rubber (NR) was compounded with polyhydroxybutyrate-co-hydroxyvalerate (PHBV) to improve mechanical properties for making a composite to be used in packaging applications. Gamma radiation technique was used to improve adhesion properties between these materials. The results showed that gamma radiation could induce cross-linking between NR and PHBV. The SEM micrograph illustrated the radiated NR/PHBV blends with gamma dose 5 kGy, 10 kGy and 15 kGy presenting a good adhesion at the blend interface. The investigation by FTIR, showing the appearance of small peaks at 2950 and 2997 cm-1 related to CH3 asymmetric stretching, also confirmed the cross-linking after the exposure of the NR/PHBV blend to gamma radiation. Also, the tensile results supported cross-linking between NR and PHBV. The elongation at break of NR/PHBV blend decreased when increasing dosage of gamma ray from 0 kGy to 15 kGy. © (2013) Trans Tech Publications, Switzerland.


Chatakanonda P.,Kasetsart University | Wansuksri R.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University
Kasetsart Journal - Natural Science | Year: 2011

Native cassava starch was subjected to modifications by annealing and acid hydrolysis. The effects of annealing on the susceptibility to acid hydrolysis, granular morphology and size distribution, molecular structure and the physico-chemical properties of cassava starch were investigated. The acid hydrolyzed starch granule surface became slightly roughened with a preserved birefringence pattern. Smaller granules were obtained after acid hydrolysis with fragments of granules observed after prolonged hydrolysis for 16 and 32 d. The molecular weight distribution of cassava starch remained unchanged after annealing while degradation of starch components occurred to differing extents after acid hydrolysis. No difference in acid hydrolysis extent was observed between native and annealed cassava starches. Acid hydrolyzed starches possessed significantly lower pasting viscosity than native and annealed starches. In general, the swelling power of cassava starch decreased while solubility increased after longer hydrolysis time. Gelatinization temperatures slightly increased during the first phase of hydrolysis and then decreased accompanied with broader endotherms. A significant increase in gelatinization enthalpy was observed in starch hydrolyzed for 16 and 32 d. The extent of retrogradation of cassava starch increased progressively with decreasing molecular weight of the acid hydrolyzed starches. In addition, the glass transition temperatures of amorphous native and annealed cassava starches at limited moisture were depressed successively with increasing hydrolysis time.


Poonsit L.,Kasetsart University | Sunthornvarabhas J.,Cassava and Starch Technology Research Unit | Akira I.,Tokyo Institute of Technology | Lertworasirikul A.,Kasetsart University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

The PEO/PLLA composite nanofibrous membranes were prepared by electrospinning technique for liquid phase filtration application. In this experiment, PLLA homopolymer and PLLA-PEG copolymer were added into PEO solution to increase hydrophobicity of nanofibrous membrane surface. PLLA content was fixed at 30% by weight of total solid. Morphology and fiber diameter were characterized from scanning electron microscope (SEM) images. Fiber diameters of PEO/PLLA homopolymer and PEO/PLLA-PEG copolymer are 582±78 nm and 657±167 nm, respectively. Surface wettability property of PEO/PLLA composite nanofibrous membranes were measured by apparent water contact angle. The apparent water contact angle value of PEO/PLLA is 120°±2°, while PEO/PEG-b-PLLA is 99°±7°. The surface wettability of PEO/PLLA composite nanofibrous membranes can be modified by varying type of polymer. © 2014 SPIE.


Sriroth K.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University | Piyachomkwan K.,Cassava and Starch Technology Research Unit | Wanlapatit S.,Cassava and Starch Technology Research Unit | Nivitchanyong S.,National Metal and Materials Technology Center
Fuel | Year: 2010

The abundance of low-cost feedstock and the cost-effective technology are of great importance for reinforcing industrialization of bioethanol for fuel use as sustainably-sourced and eco-friendly energy. This paper describes improved techniques that increase the root productivity of cassava (Manihot esculenta Crantz) and its conversion to bioethanol by the energy-saving technology being developed in Thailand. The productivity of cassava roots can be significantly increased from 22 to 60 tons/ha simply by applying yield improved varieties and good cultivation practices; important ones are soil plowing, high stake quality, weed control, good planting and harvesting period, land conservation with organic fertilizers and water irrigation. Currently, the world production of cassava is around 220 million tons per annum with the average yield of 12 tons/ha and the total acreage of 18.5 million ha. If the root productivity increases, for instance, by 5 tons/ha, around 90 million tons of roots are produced which can be converted to 15,000 ML of ethanol by Simultaneous Saccharification and Fermentation (SSF) process, a current production process of which cooked and enzymatically-liquefied cassava materials are subjected to saccharifying enzymes and yeasts in concert. The promising energy-saving technology for converting cassava chips to ethanol has also been introduced at a pilot scale by using a granular starch hydrolyzing enzyme in an uncooked process. © 2009 Elsevier Ltd. All rights reserved.


Sangseethong K.,Cassava and Starch Technology Research Unit | Chatakanonda P.,Kasetsart University | Wansuksri R.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University
Carbohydrate Polymers | Year: 2014

The influence of reaction parameters on the carboxymethylation of rice starches with different amylose contents was investigated. Rice starches with varying amylose contents showed various degrees of susceptibility to the reaction conditions. The maximum degree of substitution (DS) for all three rice starches was obtained under similar reaction conditions which involved a reaction medium consisting of isopropanol-water at the ratio of 90:10, a molar ratio of NaOH:AGU at 1.5 and a reaction temperature and time of 40 °C and 3 h. Under these conditions, the DS for all rice starches was similar; however, when the reaction was performed under conditions using lower NaOH concentration, the effect of starch types on the DS was observed. The results could be explained in terms of the granular/structural features of the different rice starches, their degrees of granular swelling as influenced by the reaction conditions and the accessibility of the etherifying reagents to starch molecules. © 2014 Elsevier Ltd. All rights reserved.


Bertoft Eric E.,Swedish University of Agricultural Sciences | Laohaphatanalert K.,Kasetsart University | Piyachomkwan K.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University
International Journal of Biological Macromolecules | Year: 2010

The aim of this work was to analyse the organization of unit chains inside clusters of cassava amylopectin β-Limit dextrins of the clusters and partly fragmented clusters (sub-clusters) were isolated previously [Laohaphatanaleart et al., Int. J. Biol. Macromol. (2010) doi:10.1016/j.ijbiomac.2010.01.0049] and were now hydrolysed extensively with the α-amylase (liquefying type) of Bacillus subtilis into small, branched building blocks. The blocks were size-fractionated and characterized structurally. The smallest blocks predominated in the clusters. They were single branched and possessed a degree of polymerization (DP) of 5-9. Blocks with DP 10-15 were double branched and constituted the second largest group. The clusters of cassava amylopectin, which were of rather uniform size, possessed typically 7-9 building blocks, and all clusters contained similar size-distributions of the blocks. The inter-block chain length was 7-8 residues. The possible mode of attack by the enzyme between the building blocks is discussed. A model of the building block organization in the clusters is presented, in which the structural roles of different sub-groups of clustered chains are suggested. A three-dimensional model suggests a possible organization of the building blocks inside the amorphous lamellae in the granular starch. © 2010 Elsevier B.V.


Laohaphatanaleart K.,Kasetsart University | Piyachomkwan K.,Cassava and Starch Technology Research Unit | Sriroth K.,Kasetsart University | Bertoft E.,Swedish University of Agricultural Sciences
International Journal of Biological Macromolecules | Year: 2010

The enzyme α-amylase from Bacillus subtilis was applied to partly hydrolyze purified cassava amylopectin into groups of clusters, which were called domains. The domains were further size-fractionated by methanol precipitation and then subjected to a second stage of α-amylolysis until the rate of hydrolysis was slow in order to release the single clusters. All domain and cluster fractions were hydrolyzed with β-amylase into β-limit dextrins. The size distribution and chain composition of the β-limit dextrins were analyzed by gel-permeation chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection, respectively. The sizes of the clusters in the form of β-limit dextrins were uniform with an average degree of polymerization of 67-78. The distribution profiles of B-chains were similar in all cluster fractions, which suggested that the internal structure of the cassava amylopectin clusters was homogenous. Long B-chains were involved in the interconnection of clusters in the domain fractions. These were cleaved and a new group of chains of intermediate length was produced by the α-amylase together with short chains. In the isolated clusters, however, some chains corresponding to long B-chains still remained, which is not predicted by the traditional cluster model of the amylopectin structure. Instead, the alternative two-directional backbone model could explain the mode of interconnection between the clusters. © 2010 Elsevier B.V.

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