Yam Starch Research Articles

Drying of yam starch (Discorea ssp.) and glycerol filmogenic solutions at different temperatures

The objective of the present study was to obtain and model drying curves of filmogenic solutions at the temperatures of 25, 30, 35, 40 and 45 °C, consisting of different concentrations of starch and glycerol. The percentage of yam starch influenced the initial moisture content, while the critical moisture content varied as a function of the concentration of starch and temperature applied during drying of the filmogenic solutions. Glycerol concentration did not influence any of the parameters analyzed. Models for the two distinct phases (constant and decreasing drying periods) fit well for all drying temperatures and compositions, with average relative error values less than 10%. The interaction between starch content and temperature influenced the drying rate parameters during the constant period and the diffusion coefficients.

Hydrothermal Treatment of Water Yam Starch in a Non‐granular State: Slowly Digestible Starch Content and Structural Characteristics

Gelatinized water yam starch was subjected to hydrothermal treatment (25, 30, and 35% moisture content for 1, 8, 16, and 24 h at 100 °C) and characterized by X-ray diffractometry, solid-state ¹³C cross-polarization and magic-angle spinning nuclear magnetic resonance, differential scanning calorimetry, and digestibility analysis. The slowly digestible starch (SDS) content of the starch treated at 30% moisture content for 24 h reached 49.1%, 31.9% higher than that of the control starch. The B-type pattern of native starch was re-crystallized to the A-type by hydrothermal treatment. The SDS content showed negative correlations with T(o), T(p), T(c), and T(r), but showed a positive correlation with melting enthalpy. Furthermore, SDS was positively correlated with hydrothermal reaction time, moisture content, relative crystallinity, and the double-helix proportion. The structural changes in hydrothermally treated water yam starches resulted in the enhancement of SDS. The hydrothermally treated water yam starch could be used as a food ingredient for slow-energy supply or dietary fiber.

Effects of Water Yam and Corn Starches on the Interacting Variables Influencing the Disintegration of Chloroquine Phosphate Tablets

The individual and effects of interaction of nature (X) and concentration (Y) of disintegrant and the relative density (Z) on the mechanical and release properties of chloroquine phosphate tablets were studied using a 23 factorial experimental design. Water yam starch (“low” level) and corn starch (“high” level) were used as disintegrants at concentrations of 5.0% and 20.0% w/w. The mechanical properties were assessed using the crushing strength (CS) and friability (F) and the release properties by the disintegration time (DT) and dissolution time (t80). Increasing the concentration of disintegrants and the relative density of tablets resulted in increase in CS, but decrease in F, DT and t80. The ranking of the individual coefficient values was Z >X >Y for CS, Z > X>Y for F and DT, and Y>X>Z for t80 while that for the interaction coefficient was X-Z> Y-Z > X-Y for CS, Y-Z> X-Z > X-Y for F, Y-Z> X-Y> X-Z for DT and t80. Changing the disintegrant from corn starch to water yam starch resulted in decrease in CS, DT and t80 but increase in F. The results showed considerable interaction between the variables employed and suggested that water yam could be an alternative disintegrant to corn starch particularly where faster disintegration and release are required. DOI: http://dx.doi.org/10.3329/dujps.v10i1.10011 DUJPS 2011; 10(1): 21-28

Applications of Infrared Spectroscopy in the Analysis of Ordered Structure of Starch Grain

Fourier transform infrared spectroscopy (FTIR) is used to study the ordered structure of starch grain, which has two modes: transmittance and attenuated total reflectance (ATR). In this paper, the different deconvolution parameters of spectra were applied to compare their effects on FTIR spectra in studying the ordered structure of starch grain. The results indicated that the different deconvolution parameters had significant effects on FTIR spectra and the intensities of relative peaks. The peak half-width of 19 cm 1 and the resolution enhancement factor of 1.9 were ideal deconvolution parameters of spectra to obtain the better results. Native starches had A, B, and C three types of crystalline, their FTIR spectra showed some differences. Potato and Chinese yam starches had similar ATR-FTIR spectra, which were different from that of rice starch. However, rice and potato starches had similar transmittance-FTIR spectra, which were different from that of Chinese yam starch. The water content of sam- ple affected the spectra of ATR-FTIR, but this effect was not detected when water content exceeded 60%. The ATR-FTIR spectra showed that the hydrolysis of amorphous structure in starch grain was faster than that of ordered structure during acid treatment. The ordered degree of structure in starch grain increased with increasing time of acid hydrolysis. The amyloglucosidase hydrolysis had no significant effect on the ordered degree of structure at the outside of starch grain by the ATR-FTIR spectra, but the ordered degree of structure of whole starch grain significantly increased with enzyme hydrolysis according to the transmittance-FTIR spectra. The amylose content is an important physicochemical property in determining the starch quality. Rice starches with dif- ferent amylose contents showed the similar ATR-FTIR spectra. These results would be very useful for the application of FTIR to the analysis of ordered structure of starch grain.

Effect of the mode of incorporation on the disintegrant properties of acid modified water and white yam starches

Acid modified starches obtained from two species of yam tubers namely white yam –Dioscorearotundata L. and water yam –D. alata L. DIAL2 have been investigated as intra- and extra-granular disintegrants in paracetamol tablet formulations. The native starches were modified by acid hydrolysis and employed as disintegrant at concentrations of 5 and 10% w/w and their disintegrant properties compared with those of corn starch BP. The tensile strength and drug release properties of the tablets, assessed using the disintegration and dissolution (t50 and t80 – time required for 50% and 80% of paracetamol to be released) times, were evaluated. The results showed that the tensile strength and the disintegration and dissolution times of the tablets decreased with increase in the concentration of the starch disintegrants. The acid modified yam starches showed better disintegrant efficiency than corn starch in the tablet formulations. Acid modification appeared to improve the disintegrant efficiency of the yam starches. Furthermore, tablets containing starches incorporated extragranularly showed faster disintegration but lower tensile strength than those containing starches incorporated intragranularly. This emphasizes the importance of the mode of incorporation of starch disintegrant.

Thermal properties of new varieties of yam starches

AbstractStarches isolated from yam varieties of Dioscorea alata and Dioscorea cayenensis‐rotundata species were prepared at different time–temperature conditions and characterised by DSC, amperometric iodine titration, light microscopy and rheology and compared to native and chemical modified tapioca starches. The observation by light microscopy showed different morphologies of the granules when heated above 100°C and the tendency for disintegration decreased in the order native tapioca starch > yam starch > modified tapioca starch. Differences between yam and tapioca starches were also revealed by DSC. Yam starch enthalpy is higher than tapioca starch, but the peak temperature is low. However, the significant differences between yam and the other tested starches were found in terms of their rheological behaviour. The viscosity of yam starch was very stable at high temperatures on the viscograph. With this property, yam starch can be used as thickening and gelling agent in food.

Extracellular amylase production of a thermotolerant Fusarium sp: isolated from Eastern Nigerian soil

In this work, an α- amylase producing Fusarium sp. was isolated from the soil at 50 0C. Growth and enzyme production occurred at 30, 45 and 55 oC. Soybean meal at 1% concentration, supplemented with 0.2% NH4Cl and 2.5% corn starch elicited the highest amylase yield. Optimum pH for the enzyme was pH 6.5 which retained over 60% of its activity after 24 h incubation at the pH range of 4.5-7.0. The enzyme showed high activity from 40-70 0C with optimal activity at 50 oC and 78% activity was retained after incubation at 70 oC for 30min. Catalytic function of the crude amylase was stimulated by Mg (136%), Ca (118%) and Zn (118%) at 2mM concentrations. The enzyme hydrolyzed cassava, potato and yam starches effectively.

Effect of blend levels on composite wheat doughs performance made from yam and cassava native starches and bread quality

The effects of refined wheat flour substitution with two native starches from yam tuber and cassava root, and two commercial products, a specialty starch, C*Actistar and a wheat bran flour, at 10%, 20%, 30%, 40% and 60% dry basis, on the rheological properties of dough and bread characteristics, have been examined. In general, during the mixing phase, the substitution of white wheat flour for starch or wheat bran flour had a tendency to modify the flour strength from strong to weak, depending on the nature of the added fraction and the level of substitution. Yam starch and wheat bran flour weakened dough strength to a lesser extent in comparison with cassava starch, and by far, the resistant starch, C*Actistar. In addition, differences in dough expansion appeared among the botanical origins of composite dough and the blend proportions, during the fermentation phase. White wheat flour substitution for yam starch up to 30% or cassava starch up to 20% led to kinetics expansions of resulted doughs close to that of the control, while those of doughs containing C*Actistar starch or wheat bran flour were significantly slower than that of the control, whatever the level of substitution. The baking phase showed that yam starch enriched breads from 10% to 40% of substitution and cassava starch enriched breads from 10% to 30% of substitution gave as bulky loaves as the refined wheat bread. Beyond these concentrations, the resulting breads were less voluminous. Hedonic tests revealed that, 30% yam starch substitution and 20% added cassava starch led to composite breads which met consumer satisfaction on all attributes, as the control.

Physicochemical, crystalline, and thermal properties of native, oxidized, acid, and enzyme hydrolyzed Chinese yam (Dioscorea opposite Thunb) starch

AbstractNative yam starch was modified by oxidation (with sodium hypochlorite), acid, and enzyme (with gluco‐amylase), respectively. Ash content, fat content, protein, and AM contents were reduced following modifications. All the modifications reduced swelling capacity whereas improved the solubility. The SEM of the native starch showed the presence of large oval or spherical to small irregular‐shaped granules, however, oxidation and hydrolysis caused collapse of the granules. From the XRD, the typical C‐type XRD pattern of the native starch changed to the typical A‐type XRD pattern of the three modified starches. The above results also demonstrated that amorphous region of yam starch granules was preferentially degraded than crystalline region of granules. DSC showed that oxidation and acid/enzyme hydrolysis reduced peak temperature of gelatinization (Tp) of native starch significantly. Enthalpy of gelatinization (ΔH) of oxidation and enzyme starch was reduced but it has no obviously change following acid modification.

Producción de Jarabes Edulcorantes por Hidrólisis Enzimática del Almidón de Ñame Variedad (Dioscorea rotundata)

En el proceso de obtención de jarabes edulcorantes por hidrólisis enzimática del almidón de ñame espino (Dioscorea rotundata), el almidón fue extraído por medio de un rayado, lavado, sedimentado y posterior secado. Se cuantificó el rendimiento teniendo en cuenta la cantidad de materia prima inicial y se le determinó la concentración de almidón, amilosa, amilopectina, fibra cruda, cenizas, proteína, grasas y humedad acorde con lo exigido en las normas AOAC, COVENIN e ICONTEC. La hidrólisis enzimática del almidón se realizó aplicando ∂- amilasa, glucoamilasa y pululanasa en soluciones de almidón al 36 y 46% p/p variando el orden de aplicación de la glucoamilasa y pululanasa; se determinó el pH, grados Brix, humedad, azúcares reductores (AR), azúcares totales (AT) y el equivalente dextrosa (ED) en los jarabes obtenidos. En la licuefacción se obtuvieron jarabes edulcorantes intermedios con un ED del 18,81% y el 22,15%. Jarabes de baja y media conversión con un ED entre el 34-45% en la primera sacarificación y jarabes de alta conversión con un ED entre el 75-79 % como producto final. Los valores anteriores permiten la utilización del almidón de ñame espino para la producción de jarabes de múltiples usos en diferentes procesos de la industria agroalimentaria.

Comparative study of physicochemical properties of breadfruit ( Artocarpus altilis) and white yam starches

Starch from seedless breadfruit ( Artocarpus altilis) was isolated and its granule characteristics, structural, physicochemical and rheological properties compared with white yam starch. Both starches exhibited a B-type diffraction patterns with a crystallinity of 36.2% for breadfruit starch and 37.3% for white yam. The two starches differed in granule size distribution and morphology; while breadfruit starch consisted of small, irregular shaped and aggregated granules (2.3–8.4 μm), white yam starch granules were large (19.2–30.8 μm), smooth and uniformly polyhedral. The amylose content and peak gelatinization temperature were different for breadfruit starch (20.0%; 69.3 °C) and white yam starch (22. 8%; 70.2 °C). The gelatinization temperature increased while the enthalpy decreased with increase in sodium chloride concentration for both starches. The starch molecules of breadfruit have a lower weight average M w (1.72 × 10 7 g/mol) compared with white yam starch ( M w = 2.32 × 10 7 g/mol). The swelling power (SP), amylose leaching (AML) at 95 °C, and paste clarity (PC) at 1% (w/w) of breadfruit starch (SP, 39.4 g/g; AML, 5.23%; PC, 2.25%) were lower than those of white yam starch (SP, 49.8 g/g; AML, 10.9%; PC, 12.79%). Its shear viscosity was lower but its ability to withstand viscosity breakdown was higher than white yam starch. The properties of breadfruit starch indicate it would require modification to improve water binding capacity and clarity of the paste, and reduce retrogradation. However, the small granule size of breadfruit starch makes it a candidate for application as a dusting starch.

Physicochemical, Functional, and Macromolecular Properties of Waxy Yam Starches Discovered from “Mapuey” (Dioscorea trifida) Genotypes in the Venezuelan Amazon

"Mapuey" tubers in Venezuela are staple food for indigenous peoples from the Caribbean coast and Amazon regions. Noticeable differences between genotypes of yam starches were observed. Granules were large, triangular, or shell-shaped with monomodal particle size distribution between 24.5 and 35.5 μm. Differential scanning calorimetry (DSC) analyses revealed onset gelatinization temperatures from 69.1 to 73.4 °C with high gelatinization enthalpy changes from 22.4 to 25.3 J g(-1). All X-ray diffractograms of starches exhibit B-type crystallinity. Crystallinity degrees varied from 24% to 40%. The highest crystallinity was found for the genotype having the highest amylose content. Iodo-colorimetric, amperometric, and DSC amylose determinations varied from 1.4 to 8.7%, 2.2 to 5.9%, and 1.4 to 3.5% for Amazonian genotypes, in comparison with commercial Mapuey starches: 12.0, 9.5, and 8.7%, respectively. Solubility and swelling power at 90 °C varied from 2.1 to 4.4% and 20.5 to 37.0%, respectively. Gel clarity fluctuated from 22.4 to 79.2%, and high rapid visco analyzer (RVA) viscosity was developed at 5% starch suspension (between 1430 and 2250 cP). Amylopectin weight average molar mass M(w), radius of gyration R(G), hydrodynamic coefficient ν(G), and apparent molecular density d(Gapp) were determined using high-performance size exclusion chromatography (HPSEC) and asymmetrical flow field flow fractionation (A4F) techniques coupled with multiangle laser light scattering (MALLS) on the Dioscorea trifida genotypes exhibiting the lowest and highest amylose contents. Amylopectins showed very similar molecular conformations. M(w) values were 1.15 × 10(8) and 9.06 × 10(7) g mol(-1) using HPSEC and A4F, respectively, thus, 3-5 times lower than those reported with the same techniques for other yam species, and very close to those of potato and cassava amylopectins. This discovery of a new natural amylose-free starch in the neglected yam "Mapuey" could present some potential for the food industry.

Granule structural, crystalline, and thermal changes in native Chinese yam starch after hydrolysis with two different enzymes–α‐amylase and gluco‐amylase

AbstractStarch extracted from Chinese yam was characterized by scanning electron microscope (SEM), X‐ray powder diffractometer (XRD), and differential scanning calorimeter (DSC) in the process of enzymatic hydrolysis. Yam starch was digested by α‐amylase and gluco‐amylase for different lengths of time, respectively, and two different enzymatic hydrolysis results were compared. The most notable phenomenon revealed by SEM after α‐amylase hydrolysis was the formation of the cavum in the center of the starch granules, while after gluco‐amylase hydrolysis, the outer layer of the granules was peeled off and then some granules even broke into pieces. The XRD of the two enzyme hydrolyzed starches revealed the crystal type of the starch changed from typical C‐type XRD pattern to the representative A‐type pattern in the process of enzymatic hydrolysis. The above results also demonstrated that the partially B‐type polymorph was more easily degraded than A‐type. The thermal result showed that the modified yam starches by both enzymes exhibited increased peak gelatinization temperatures (Tp) and decreased gelatinization enthalpy (ΔH).

FRUCTOSE SYRUP OBTENTION FROM ENZYMATIC HYDROLYSED OF YAM STARCH (<I>Dioscorea alata</I> and <I>Dioscorea rotundata</I>)

This investigation evaluated the yield of fructose syrup production from extracted starch of two yam species ( Dioscorea alata , var. Diamond and Dioscorea rotundata , var. Espino). The experiment was conducted using an at random experimental design of multiple categorical factor analysis with two factors: a substrate concentration factor at five levels: 10, 20, 30, 40, 50% p/v and the yam species factor at two levels ( Dioscorea alata , var Diamond and Dioscorea rotundata , var Espino). To obtain fructose, initially glucose syrups were prepared by enzymatic hydrolysis of yam starch using the enzymes of Novozymes®,alpha-amylase Termamyl 120L (liquefaction stage) and AMG 300L (saccharification stage). At this stage, dextrose maximum equivalents (ED) obtained were 98.28 and 96.84 for a substrate concentration of 30%w/v. In a later stage isomerisation from glucose syrups to fructose syrups using the immobilized enzyme Sweetzyme of Novozymes® was carried out. The best results were achieved with substrate concentrations of 30% p/v for both yam species, which showed fructose concentrations of 220.57 and 210.36 g/L with conversions of 71.46% and 67.28% in Espino and Diamond yams respectively. No statistically significant differences were observed between the yam species ( D. alata var. Diamante and D. rotundata var. Espino) at a confidence level of 5%, regarding the production of fructose syrup.

Study on physico-chemical properties of dialdehyde yam starch with different aldehyde group contents

Dialdehyde yam starches (DASs) are prepared and characterized. Compared with native starch, viscosity average molecular weight of DASs decreases, and the extent of degradation depends on content of the aldehyde groups. Fourier transform infrared (FT-IR) spectra confirm that the characteristic peak for C O group at 1732 cm −1 is enhanced with the increasing of content of the aldehyde groups. Scanning electron microscopy (SEM) micrographs show that the surface of starch granules becomes wrinkled. X-ray diffraction (XRD) patterns clearly indicate that their crystallinity decreases with the increasing content of the aldehyde groups before they become amorphous at higher oxidation states. The experimental results of thermogravimetric analysis (TGA) show that DASs have poor stability as compared to native starch. With the increase in content of the aldehyde groups, the thermal stability of DAS declines gradually. According to the results of differential scanning calorimetry (DSC), gelatinization temperature ( T o and T p) of DASs are increased, whereas the gelatinization enthalpy decreased.

Effect of binder processing on feed quality

This study was carried out to investigate the effect of binder processing on the quality of feed, viz; pelletabilty, hardness, friability and water stability. Four different starch sources were investigated; yam starch, corn starch, rice starch and cassava starch. Each starch was formulated into two diets employing two processing methods; cooked and un-cooked. The statistical analysis of the physical parameters of the diets indicated significant differences (P < 0.05) between different binders. Yam starch, rice starch, and cassava starch performed best in un-cooked form, while Corn starch exhibited best water stability in cooked form. The outcome of the research establishes the need for an appropriate method of binder processing which will assist fish farmers in the production of water stable pellets.Key words: Binders, processing, water stability.

Etude de l'amidon d'igname (dioscorea cayenensisrotundata) variete kponan en granulation par vobe humide dans la formulation de comprimes a base de chloroqueve diphosphate.

The aim of this work was to study the behaviour of yam starch "KPONAN" variety as a diluent on tablets formulation based on chloroquine diphosphate. In a previous study, we had investigated the technological, galenic and biogalenic properties of grains before and after compression compared The to traditional starch on Pharmacopoeia i.e. maize and potato starches. The results have demonstrated that KPONAN starch possess an excellent ability for compression with an average hardness of tablets of 9.4 ± 0.7 Kp, a weight average of 460.2 ± 2.4 mg and a disintegration rate of1.94%. Disintegration time rates were 8.13 ± 0.4 min and 5.07 ± 0.5 min, respectively, for formulas with and without disintegrant agent. Times of liberation of 50% of chloroquine were 5.0 ± 0.1 min and 3.0 ± 0.1 min, respectively for formulas with and without disintegrant agent. We conclude that KPONAN variety of yam starch can be used successfully in tablet formulation as diluent, binder and disintegrant. It behaved in compression after wet granulation like potato starch.

Microstructure and physico-chemical bases of textural quality of yam products

The texture of pounded yam is the main attribute of this traditional dish, one of the preferred ways of consuming yam in West Africa. We integrated functional properties and cell microstructure to describe or predict the textural quality of pounded yam. The firmness and adhesiveness of pounded yam prepared from six cultivars were measured. In parallel, the thermo-mechanical properties (DMA, DSC) and starch behaviour were also determined while the structure of raw, cooked and pounded yam was observed using Scanning Electron Microscopy, Light Microscopy and Confocal Laser Scanning Microscopy. No significant correlation was found linking DMA, DSC measurements with the textural quality of pounded yam (adhesiveness, firmness). Conversely, multiple regressions showed that 75% of the variation in firmness could be explained by the dry matter, soluble starch and amylose content of the pounded yam. In addition, CLSM revealed a thicker cell wall in Florido, a cultivar known for its bad pounding ability. We hypothesize that pectin, the major component of cell wall middle lamella, plays a role in the textural quality of pounded yam.

Evaluation of Yam Starch (Discorea rotundata) as Aquatic Feed Binder

Evaluation of Yam Starch (Discorea rotundata) as Aquatic Feed Binder

Evaluación de la producción de jarabes glucosados por medio de la aplicación de enzimas amilasas sobre el almidón de ñame ( Dioscorea rotundata)

Se produjo jarabe edulcorante por hidrólisis enzimática del almidón de ñame espino (Dioscorea rotundata). El almidón se extrajo mediante el proceso físico desarrollado por CORPOICA - Colombia en el 2003, se cuantificó el rendimiento teniendo en cuenta la cantidad de materia prima inicial y se le determinó la concentración de almidón, amilosa, amilopectina, fibra cruda, cenizas, proteína, grasas y humedad acorde con lo exigido en las normas AOAC e ICONTEC. La hidrólisis enzimática del almidón se realizó aplicando α- amilasa, glucoamilasa y pululanasa en soluciones de almidón al 36 y 46% p/p variando el orden de aplicación de la glucoamilasa y pululanasa; se determinó el pH, grados Brix, humedad, azúcares reductores (AR), azúcares totales (AT) y el equivalente dextrosa (ED) en los jarabes obtenidos. En la licuefacción se obtuvieron jarabes edulcorantes intermedios con un ED de 18,81% y 22,15%. Jarabes de baja y media conversión con un ED entre 34-45% en la primera sacarificación y jarabes de alta conversión con un ED entre 75-79 % como producto final. Los valores anteriores permiten la utilización del almidón de ñame espino para la producción de jarabes de múltiples usos en diferentes procesos de la industria agroalimentaria.