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Waxy cassava roots of nine varieties successfully developed in Thailand by a non-genetic modification (non-GM), conventional breeding method were used for extracting starches and their starch physico-chemical properties were evaluated and compared with normal cassava starches, commercial waxy starches (i.e., waxy maize starch and waxy rice starch) and commercial stabilized starches (i.e., acetylated starch and hydroxypropylated starch). All waxy cassava varieties provided starches without amylose while normal cassava starches contained 18%&ndash, 20% amylose contents. As determined by a Rapid Visco Analyzer (RVA) at 5% (dry basis), waxy cassava starches had the highest peak viscosity and the lowest setback viscosity. Cooked paste of waxy cassava starches had the greatest clarity and stability among all starches during storage at 4 ℃ for 7 days as evidenced by its high light transmittance (%T) at 650 nm. No syneresis was detected in waxy cassava starch gels after subjecting to four freeze-thaw cycles (4 weeks) indicating high potential use of waxy cassava starches, free from chemicals, to replace stabilized starches as thickening and texturing agents in food products.

Poly(lactic acid) has been electrospun into submicron fibers with embedded cassava starch matrix. The fibers had average fiber diameters between 140 and 680 nm. The starch content varied from 10 to...

A series of 17 samples represented a diverse collection of different starch granules from different plants. The amylose content ranged from 0% to 28% and the crystallinity was established to represent A, B and C allomorphic types. The amylopectin components were isolated and their unit chain distributions analysed by anion-exchange chromatography. The internal unit chain profiles were obtained from the φ,β-limit dextrins. The internal profiles possessed two major fractions of short and long B-chains. The long B-chains were divided into two subgroups also found in the profiles of the whole amylopectins. The short, internal B-chains contained also two subgroups in all samples, of which one was a major group at DP 8–25, and the other was a minor group at DP 3–7. On the basis of the internal chain distribution profiles of (i) the long chains, reflecting the interconnection of clusters, and (ii) the short chains, reflecting the internal structure of the clusters, the samples were divided into four structural groups with typical characteristics. It was found that the unit chain profiles of the whole amylopectins could be divided into the same characteristic groups. The positions of the internal unit chains were theoretically traced into their original lengths in the profiles of the whole amylopectins. It was concluded that A-chains generally overlap with the shortest B-chains at DP 13–23, which coincided with fraction fb 1 of the periodic intervals described by Hanashiro et al. [Hanashiro, I., Abe, J.-i., & Hizukuri, S. (1996). Carbohydrate Research, 283 , 151–159].

The extent of irrigation of crops in the field not only affects crop yield but also the functionality of the harvested product. This irrigation effect severely affects the processing response of starch harvested from Cassava and leads to industrial quality control problems. In this paper we show how the NMR transverse proton relaxation spectrum is a sensitive probe of the effect of irrigation on cassava starch functionality. The results suggest that increased irrigation results in a looser packing of the amylose and amylopectin chains in the cassava starch granule that facilitates their plasticization and gelatinization.

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.

Nonwaxy rice starch was crosslinked using sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of crosslinking (9.2, 26.2 and 29.2%). Rice starch suspensions were heated from −40 to 100 °C at 2 °C/min 1) in a Differential Scanning Calorimeter and 2) under a light and polarized light microscope, in order to analyze for glass and/or melting transitions. The size of the starch granules increased with increasing temperature; the onsets for dramatic increase in size were approximately 55 °C for native and control samples and approximately 60 °C for crosslinked samples. A twostep swelling pattern was observed above 55 °C corresponding with the biphasic endothermic peaks as well as the discontinued (biphasic) loss in birefringence (due to heterogeneity in transition temperature). No disruption of granules was observed in any crosslinked samples. The low temperature transition (55–70 °C) involved both a loss in molecular order (possibly also melting) and swelling which were partly inhibited by crosslinking. Crosslinking delayed the gelatinization process (without decreasing total enthalpy) by restricting swelling and reducing the hydration of starch. No evidence of glass transition was observed in any samples studied.

Nonwaxy rice starch was cross-linked with sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of cross-linking (9.2, 26.2, and 29.2%). The objective was to investigate the influence of cross-linking on thermal transitions of rice starch. Starch suspensions (67% moisture) were heated at 2°C/min using differential scanning calorimetry (DSC) to follow melting transition of amylopectin. Biphasic transitions were observed at ≈60–95°C in all samples. Melting endotherms of amylopectin shifted to a higher temperature (≤5°C) with an increasing degree of cross-linking, while there was no dramatic change in enthalpy. Recrystallization during aging for 0–15 days was significantly suppressed by cross-linking. The delayed gelatinization and retrogradation in crosslinked starch were evident due to restricted swelling and reduced hydration in starch granules. Glass transition temperature (Tg) measured from the derivative curve of heat flow was -3 to -4°C. No significant change in Tg w...

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.

Mobility and distribution of water in cassava (rainy and drought crops) and potato starches were studied by solid state and NMR relaxometry as a function of H(2)O and D(2)O contents ranging from 0 to 44% (dry basis). Measurements of relative mobility derived from (2)H solid state NMR were based on relative area and line shape analysis. The narrow peak (mobile component) started to show at 5% and increased with increasing D(2)O content. This increase in mobile fraction was accompanied by a line narrowing. The mobile fractions of deuterons reached a98% level above 15% D(2)O, which is well below the water holding capacity of starch ( approximately 27%) and the previously assigned "glassy-rubbery transition point" (24.3%; Jouppila, K.; Roos, Y. H. The physical state of amorphous corn starch and its impact on crystallization. Carbohydr. Polym. 1997, 32, 95-104). This reconfirms the liquidlike nature of water in the so-called glassy state of starch granules. The plasticization effect of water on starch chains was observed at 14-17% for cassava and potato starches as indicated by the T(1) minimum. This, however, did not seem to relate to the difference observed in swelling among the starches studied.