Effects Of Amylose Research Articles

Effects of amylose and amylopectin molecular structures on rheological, thermal and textural properties of soft cake batters

The rheological, thermal and textural properties of batter are critical for the eating and processing quality of soft cake products. Wheat starch molecular structures play an important role on these properties. However, the underlying mechanisms are not well understood. In this study, fluorophore-assisted carbohydrate electrophoresis and size-exclusion chromatography were used to measure amylopectin and amylose chain-length distribution. The obtained data were fitted with two different biosynthesis-based models, resulting in few biologically-meaningful parameters. For cake batter, the rheological, thermal and textural properties were measured by rheometer, differential scanning calorimetry and texture analyser. The length of amylose intermediate to long chains and amylopectin long chains was significantly positively correlated with the viscoelasticity of cake batter. The length of long amylose chains showed a negative correlation with the frequency value of crossover point between G′ and G″ curves. Moreover, different combinations of long amylopectin and intermediate-long amylose chains contributed to the formation of multi-endothermic gelatinization peaks. From flour-water system to flour-lipid-protein system, the main factors determining rheological and thermal properties changed from short amylopectin to long amylopectin and intermediate-long amylose chains. This study provides the first associations between starch molecular fine structure and functional properties of cake batter, which could help food industry breed and select suitable wheat varieties for improved batter quality. • The functional properties of flour-lipid cake batter were investigated in this study. • Long AP & medium and long AM chains are positively correlated with viscoelasticity. • Decrease of long AM chain length increases crossover point x value of rheology curves. • Cake batter shows two endothermic peaks in gelatinization curves. • Chain length distribution of AM is the determining factor for flour-lipid batter.

Effects of amylose and amylopectin molecular structures on starch electrospinning

The role of amylose content in electrospinning starch nanofibres is well understood, but that is not the case for the roles of the molecular structures of amylose and amylopectin. Here, correlations between starch molecular-structure parameters and electrospinnability evaluation indices (average droplet number, average bead number, and average fibre diameter) and dope properties (shear viscosity, conductivity, and surface tension) were examined. Starches with lower amounts of short amylopectin chains, higher amounts of either/or long amylopectin chains and/or lower degree of branching showed decreased viscosity of the electrospinning dopes, and resulted in a reduced average droplet number of electrospun fibre mats. The molecular sizes of amylose and whole starch, and the average degree of polymerization for amylose chains, all correlated with the shear viscosity and surface tension of dopes, and thus influenced the average fibre diameter. This expands the current understanding between amylopectin molecular structure and starch electrospinning, thereby assisting a better choice of starches for desired electrospinnability properties.

Effects of amylose and amylopectin chain-length distribution on the kinetics of long-term rice starch retrogradation

Understanding the characteristics of long-term starch retrogradation is critical for developing functional foods with desirable textural attributes. The long-term retrogradation kinetics of 10 different rice starches with a wide range of amylose content were thus investigated in this study, focusing on their relations with the starch chain-length distributions (CLDs). Correlation analysis between the retrogradation parameters from differential scanning calorimetry (DSC) with starch CLDs showed for the first time that the amylose content had a parabolic relationship with the melting conclusion temperature and enthalpy of long-term retrograded starches, indicating that the amylose component has a bi-directional effect on the long-term amylopectin retrogradation property. Furthermore, the amount of amylose short-medium chains and amylopectin medium chains were negatively and positively correlated with the melting onset temperature of long-term retrograded starches, respectively. The information learnt from this study could be applied in the rice industry to improve the textural attributes of cooked rice.

Effects of amylose and amylopectin fine structure on sugar-snap cookie dough rheology and cookie quality

Starch, the most abundant component of wheat flour, has a significant influence on sugar-snap cookie quality, but the underlying mechanisms are not well understood. In this study, the solvent retention capacity and rheological properties of sugar-snap cookie dough, and cookie physical characteristics and textural properties, were analyzed. Starch molecular structures were measured by size-exclusion chromatography (SEC) and the results parameterized using two biosynthesis-based mathematical models to obtain structure-property correlations. The results show that the viscoelasticity of sugar-snap cookie dough is positively correlated with the length of amylopectin short chains. In addition, the length of amylose short chains is positively correlated with cookie thickness and negatively correlated with its spread ratio. Starch molecular structure shows no influence on cookie hardness and fracturability. Mechanisms are proposed for these results, which could lead to new ways to improve sugar-snap cookie quality by choosing starches with appropriate structural features.

Effects of amylose and resistant starch on glycaemic index of rice noodles

Rice is generally high in glycaemic index (GI). Amylose and resistant starch (RS) play an important role in controlling the GI. The levels of amylose and RS in the mixed flours for rice noodle production (rice flours mixed with tapioca starch) were manipulated by adding high amylose maize starch. This resulted in the increase of amylose and RS from 32 to 50 and 0.4 to 16 g/100 g dry sample respectively. The mixed flour samples were used to produce rice noodles. Their GI values were estimated by an in-vitro enzymatic digestion assay and confirmed by an in-vivo method. It was found that the GI of rice noodles decreased as amylose and RS increased. However, high amylose and RS affected the texture as they reduced the tensile strength of the noodles.

Effects of amylose and phosphate monoester on aggregation structures of heat-moisture treated potato starches

For three cultivars of potato starch, heat-moisture treatment (HMT) displayed an influence on the aggregation structures at different scale levels. With HMT, the granular morphology of potato starch granules remained similarly, and an increase in the average repeat distance of semi-crystalline lamellae was observed. The crystalline structure and birefringence were also affected. Moreover, the polymorphic transformation (B→A+B) could be related to dehydration, whereas the decrease in the degree of crystallinity might be resulted from the rupture of hydrogen bonds. Interestingly, amylose could act as the backbone of the aggregation structures of potato starch to provide resistance to HMT, but phosphate monoester could promote the destruction during HMT. In addition, compared with amylose, phosphate monoester played a more significant role in changing the average repeat distance of semi-crystalline lamellae (long period) during HMT.

Supermolecular structure of cellulose/amylose blends prepared from aqueous NaOH solutions and effects of amylose on structural formation of cellulose from its solution

We previously proposed a mechanism for the structural formation of cellulose from its solution using a molecular dynamics (MD) simulation and suggested that the initial structure from its solution plays a critical role in determining its final structure. Structural changes in the van der Waals-associated cellulose molecular sheet as the initial structure were examined by MD simulation; the molecular sheet was found to be disordered due to maltohexaoses as an amylose model in terms of the hydrogen bonding system of cellulose. The structure and properties of cellulose/amylose blends prepared from an aqueous NaOH solution were examined experimentally by wide-angle X-ray diffraction and dynamic viscoelasticity measurements. The crystallinity of cellulose in the cellulose/amylose blend films was lower than that of cellulose film. The diffraction peaks of the cellulose/amylose blends were slightly shifted; specifically, (11¯0) was shifted to a higher angle, and (110) and (020) were shifted to lower angles. These experimental results probably resulted from the disordered molecular sheet, as revealed by MD simulations.

Effects of Amylose, Corn Protein, and Corn Fiber Contents on Production of Ethanol from Starch‐Rich Media

ABSTRACTThe effects of amylose, protein, and fiber contents on ethanol yields were evaluated using artificially formulated media made from commercial corn starches with different contents of amylose, corn protein, and corn fiber, as well as media made from different cereal sources including corn, sorghum, and wheat with different amylose contents. Second‐order response‐surface regression models were used to study the effects and interactions of amylose, protein, and fiber contents on ethanol yield and conversion efficiency. The results showed that the amylose content of starches had a significant (P < 0.001) effect on ethanol conversion efficiency. No significant effect of protein content on ethanol production was observed. Fiber did not show a significant effect on ethanol fermentation either. Conversion efficiencies increased as the amylose content decreased, especially when the amylose content was >35%. The reduced quadratic model fits the conversion efficiency data better than the full quadratic model does. Fermentation tests on mashes made from corn, sorghum, and wheat samples with different amylose contents confirmed the adverse effect of amylose content on fermentation efficiency. High‐temperature cooking with agitation significantly increased the conversion efficiencies on mashes made from high‐amylose (35–70%) ground corn and starches. A cooking temperature of ≥160°C was needed on high‐amylose corn and starches to obtain a conversion efficiency equal to that of normal corn and starch.

The Effects of Amylose and Starch Phosphate on Starch Gel Retrogradation Studied by Low‐field 1H NMR Relaxometry

AbstractLow‐field Nuclear Magnetic Resonance (23 MHz) was used to study the effects of the degree of phosphorylation, the amylose content and the amylopectin chain length distribution on gel retrogradation for a set of 26 starches, six of which were of crystal polymorph type A, 18 of type B and two of type C. The phosphate content ranged from 0 to 58.8 nmol Glc6P/mg and the amylose content from 0 to 72.1%. The starch pastes (13%, w/w) were measured before and after storage for six days at 35 °C. It was found that Principal Component Analysis (PCA) of the raw Carr‐Purcell‐Meiboom‐Gill (CPMG) relaxation curves from the two measurements (day 1 and day 7) could be used as a simple, illustrative way of describing the retrogradation. Three different behaviours were identified: One group of samples (mostly potato starches) slowly changed from a soft to a more rigid gel from day 1 to 7. A second group (mostly cereal starches) formed a rigid gel already before the first measurement and changed little after that. A third group comprised a few samples containing little or no amylose aged similarly to the first group of samples, but at a much slower rate. For the potato starches, a weak negative correlation (r = ‐0.63) was found between the degree of phosphorylation and the difference between the LF NMR relaxation curves of day 1 and day 7.

Effects of amylose and wheat bran on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in rats.

A basal diet (containing 20% soybean protein isolate) was supplemented with limiting amino acids (AA, methionine, threonine and tryptophan); wheat bran (WB, 24.3%); amylose (AM, 10%) or a combination of AA and WB or AM to investigate their effects on the levels of blood serum urea nitrogen (BUN), other blood parameters, growth and fecal characteristics in young rats. After 3 weeks feeding, supplementation of the basal diet with AA or WB resulted in improved growth (gain/food ratio) while the addition of AM had no effect on rat growth. Addition of WB to the basal diet had no effect on BUN while the addition of AA and AM caused about 20 and 12% reduction in BUN values, respectively. Rats fed the AA-AM diet had the lowest BUN values (42% lower than those fed the basal diet). Fresh volume, fresh weight, moisture and dry weight of feces in rats fed the WB diets were about four to five fold higher than in those fed the AM diets. The results suggested that BUN may not be a good predictor of growth and protein quality in diets containing AM or a source of dietary fiber (WB).

Retrogradation of amylopectin and the effects of amylose and added surfactants/emulsifiers: M. Gudmundsson and A-C. Eliasson, Carbohydr. Polym. 13, 295–315

Retrogradation of amylopectin and the effects of amylose and added surfactants/emulsifiers: M. Gudmundsson and A-C. Eliasson, Carbohydr. Polym. 13, 295–315

Retrogradation of amylopectin and the effects of amylose and added surfactants/emulsifiers

The retrogradation of mixtures with different amylopectin/amylose ratios and 50% (w/w) water content was followed by differential scanning calorimetry. The effect of the addition of surfactants/emulsifiers (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB) and monoglycerides) was investigated. The results showed that the relationship beween the melting enthalpy of recrystallized amylopectin and the proportion of amylopectin was not linear. Mixtures with less than 50% amylopectin showed a higher melting enthalpy than expected. The effect of surfactants/emulsifiers on that relationship was to decrease the retrogradation of all the mixtures, but they had their greatest effect on 100%-amylopectin samples and least effect on mixtures with 50% amylopectin. Thermograms obtained for 100% amylopectin with added surfactants/emulsifiers showed transitions above 100°C, thus indicating the formation of a complex between amylopectin and the surfactants/emulsifiers. This was supported by X-ray diffraction analysis, as amylopectin samples with added SDS and CTAB showed a mixture of B- and V-patterns. This complex formation between amylopectin and surfactants/emulsifiers can explain the large reducing effect of the addition of surfactants/emulsifiers on retrogradation of 100% amylopectin samples, and partly the retrogradation of other mixtures.

The microenvironmental effects of helical conformations of amylose: 9. Catalytic effects of amylose on the hydrolysis of p-substituted phenol esters and structural effects of substrates

Hydrolytic rate constants of p-substituted phenol esters of carboxylic acids with various chain lengths were measured in the 1:1(V/V)Me_2SO-H_2O.Amylose accelerates the hydrolytic rates of all substrates,but the catalytic patterns are different for long and short chain sudstrates,i.e.,acetates(2-X)show 2nd order kinetics,dodecanoates, (12-X)and hexadecanoates(16-X)follow Michaelis-Menten saturation kinetics.The dissociation constants K_d of inclusion complexes are dependent on the chain length of substrates,but no correlation can be found between K_d and the electronic effects of substituents.The rate constants k_(un),k_(obs),k_2 and k_c of 12-X and 2-X conform to the Hammett relation,the ρ values are almost the same,whether in the presence or absence of amylose.But k_(un),k_(obs) and k_c values of 16-X all cannot be correlated by the Hammett equation,presumably because of the aggregation and self-coiling of 16-X in this poor solvent.Thermodynamic parameters ⊿H_1 and ⊿S_1 of the inclusion process and activation parameters ⊿H(?) and ⊿S(?) were obtained from the temperature dependence of K_d and k_c. The results indicate that the formation of inclusion complexes between amylose and substrates is an entropy disfavored and enthapy favored process.Comparison of ⊿H(?), ⊿S(?) with ⊿H_(un)~(?) and ⊿S_(un)~(?) of the spontaneous hydrolysis shows that the acceleration of hydrolysis of long chain substrates by amylose is caused by the formation of helical inclusion complexes.The influence of intermolecular aggregation and self-coiling of 16-X on the inclusion and catalytic processes is also discussed.