Cheng-yi Lii

Effects of granular structures on the pasting behaviors of starches

ABSTRACT Japonica (Tainung 67 [TNu67]) and waxy (Taichung 70 [TCW70]) rice, normal and waxy corn, and cross-linked waxy rice and corn starches were used in an investigation of the influence of the granular structure on the pasting behavior of starch, using small amplitude oscillatory rheometry. Both normal corn and normal rice (TNu67) starches had the highest storage moduli (G′), followed by their cross-linked versions; native waxy corn and rice starches had the lowest. Native waxy starches showed paste characteristics (G′ 0.2) at concentrations of up to 35%. However, cross-linked waxy starches exhibited gel behavior at 10% concentration (cross-linked TCW70) or higher (cross-linked waxy corn starch). The degrees of swelling power were in the order: TCW70 > native waxy corn > TNu67 ≅ cross-linked TCW70 ≅ normal corn ≅ cross-linked waxy corn starches. Solubilities were in the order: normal corn > TNu67 > native waxy > cross-linked waxy starches. The addition of 2% purified amylose from ind...

Preliminary study on the degradation kinetics of agarose and carrageenans by ultrasound

Abstract The changes in intrinsic viscosity ([η]) during ultrasonic degradation of agarose, κ- and ι-carrageenans in water were investigated. Based on the concept that the random scission of glycosidic linkage basically obeys first-order kinetics, the degradation rate (k) for each short-term ultrasonication process could be obtained. The resultant k values for 0.5xa0wt% polysaccharide systems appeared to decrease quite linearly with reduced [η], in contrast to those for 1.5xa0wt% systems. Both k value and its [η]-dependence of diluted and concentrated systems were in the order of agarose>κ-carr>ι-carr, depending on the concentration of polysaccharides.

Molecular Characteristics Influencing Retrogradation Kinetics of Rice Amylopectins

ABSTRACT The enthalpy changes (ΔH) for melting of crystallites formed during retrogradation of 60% (w/w) amylopectins (AP) aged at 4°C were investigated using AP from 13 rice cultivars with well-known structural properties. According to the Avrami equation, the resultant kinetic parameters for AP retrogradation were obtained in relation to structural factors. Generally, the AP systems studied showed two stages of retrogradation behavior during early (≤7 days) and late (≥7 days) storage. The Avrami exponent for early-stage kinetics (n1, 1.04–5.54) was greater than the corresponding value for late-stage kinetics (n2, 0.28–1.52). While the Avrami K constant of the early-stage kinetics (K1, 1.0×10-5 to 2.3×10-1 day-n) was lower than the corresponding value of late-stage kinetics (K2, 4.4×10-2 to 1.4 day-n). The ΔH values for late and infinite retrogradation stages showed a significantly positive correlation with the proportions of short chain (chain length [CL] ≤ 15 glucose units) and long chain (CL = 16–100 ...

Effects of hydrogen, oxygen, and ammonia low-pressure glow plasma on granular starches

Cassava, corn, high amylose corn, potato, rice Indica, rice Japonica, sweet potato, waxy corn, and wheat starches were exposed to low-pressure ammonia, hydrogen, and oxygen plasma. In every case, depolymerization of the starch polysaccharides was noted. The extent of the depolymerization depended on the nature of the starch as well as the type of plasma applied. Among three fractions of polysaccharides distinguished by their molecular weight average, the fraction of the highest molecular weight suffered the most efficient depolymerization. The relative depolymerization for the middle- and low-molecular fractions of polysaccharides was found to be starch and plasma specific. The chemical character of the plasma had very little influence on the starch polysaccharides. Only subtle oxidation effects were observed in oxygen plasma. Low-pressure glow plasma treatment appeared to be a convenient tool for a waste-less dextrinization of starch. Manipulation of the plasma variety and the time of exposure resulted in a wide spectrum of dextrins of various molecular weights and paste-forming properties.

Kinetic compensation effect in depolymerisation of food polysaccharides

Abstract The thermal depolymerisation kinetics of agarose and κ-carrageenan in water were investigated by measurement of intrinsic viscosity ([η]). An isokinetic relationship (IKR) revealing a kinetic compensation effect in polysaccharide depolymerisation was then discovered from the obtained kinetic data and those reported in the literature. Generally, the Arrhenius frequency factor, k0, and activation energy, Ea, of depolymerisation of agarose, κ/λ-carrageenan, κ-carrageenan and schizophyllan, under commonly used thermal conditions (high temperature, in water or pH-7 solvents, without deaeration and in disordered conformation), were in the ranges of 1.8×107–7.8×1010 s−1 and 97–126 kJ mol−1, respectively. These two variables showed parallel increases when using solvents of lower pH values (especially in k0) or with deaeration, and polysaccharides in ordered conformation or at lower concentrations. The IKR for the polysaccharide depolymerisation was: ln k0/s−1=0.379.Ea/kJ mol−1–18.5 (R2=0.906), giving an isokinetic temperature (Tiso) of 317 K. Conclusively, the depolymerisation mechanism was the same for all polysaccharide systems examined.

Molecular and gelatinization properties of rice starches from IR24 and Sinandomeng cultivars

ABSTRACT The differences in pasting properties involving gelatinization and retrogradation of rice starches from IR24 and Sinandomeng cultivars during heating-cooling processes were investigated using a Rapid Visco Analyser (RVA)and a dynamic rheometer. The results were discussed in relation to the molecular structure, actual amylose content (AC), and concentration of the starches. Generally, both starches possessed a comparable AC (≈11 wt%), amylose average chain length (CL), iodine absorption properties, and dynamic rheological parameters on heating to 95°C at 10 wt% and on cooling to 10°C at higher concentrations. In contrast to Sinandomeng, IR24 amylose had a greater proportion of high molecular weight species and number-average degree of polymerization (DPn). IR24 amylopectin possessed a lower DPn and greater CL, exterior CL (ECL), and interior CL (ICL). Comparing the results of RVA analysis and dynamic rheology, the gelatinization properties and higher retrogradation tendencies of IR24 starch can be...

Correlation Between Starch Retrogradation and Water Mobility as Determined by Differential Scanning Calorimetry (DSC) and Nuclear Magnetic Resonance (NMR)

ABSTRACT Starches from nine varieties of rice, including four indica, three japonica, and two waxy cultivars, were used for the investigation of the correlation between retrogradation and water mobility. Retrogradation and water mobility were analyzed by differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) and expressed as enthalpy change (ΔH) and differential relaxation rate (ΔR2) for water-17O. Water contents were measured by DSC and Karl-Fischer methods. The results indicated that three different profiles, based on amylose content, were observed for the ΔH changes of rice starch cooks during storage. They fit well to the nonlinear regression equations of exponential rise to maximum and exponential growth models. The water content, as measured with DSC, decreased during storage but increased as measured with the Karl-Fischer method. This discrepancy might be attributed to the different characteristics of water measured by the two methods. The ΔR2 of rice starch cooks showed an in...

Changes in Retrogradation Properties of Rice Starches with Amylose Content and Molecular Properties

ABSTRACT The increases in storage modulus (G′), retrogradation enthalpy change (ΔH) and ΔH-related Avrami kinetic parameters of gelatinized rice starch dispersions at 25% (w/w) were investigated with respect to storage period, amylose content (AC), and molecular properties. Three high-AC and five low-AC rice cultivars were compared for understanding the multiple influences of AC and molecular properties involved. After refining the results of correlation analysis, the G′ of just-cooled samples changed positively, mainly with AC and additionally with the average chain length of amylose (CLAM) and the weight ratio of extra-long plus long chains to short chains of amylopectin (AP) (rAPchain). The developed ΔH on short-term storage (10 days) elevated with increasing AC and CLAM and decreasing degree of polymerization of AP (DPAP), but after long-term aging for one to three months with increasing rAPchain, especially for the low-AC cultivars examined. Greater Avrami rate constants for retrogradation could be a...

Composition Dependencies of the Rheological Properties of Rice Starch Blends

ABSTRACT The gelatinization, pasting, and dynamic rheological parameters of rice starch dispersions from Kaoshiung Sen 7 (KSS7), Taichung Waxy 70 (TCW70), and their blends were examined in relation to total starch concentration (Ct) and the property of starch components. Mixing the rice starches, especially at equivalent ratios, resulted in decreasing onset temperature for gelatinization or developing viscosity and in cold-paste viscosity, accompanied by a synergistically increased peak viscosity. The logarithmic of storage moduli, G′, for all starch dispersions except the retrograded systems of Ct = 20–30 wt%, showed two linear dependencies on the weight-average amylose content (AC) of the blends separating at a critical AC of 20 wt% (i.e., TCW70 = 25 wt%). Interestingly, the temperatures at which G′ started to increase drastically maximized on heating, and the exponent n of G′ ∝ Ctn also maximized at the same TCW70 starch concentration Generally, the elasticity of the systems after complete gelatinizati...

Effects of temperature and glycerol on the de-organisation of hsian-tsao (Mesona procumbens Hemsl) polysaccharide solution by electron spin resonance spectroscopy

Abstract The effect of different glycerol concentration on the molecular transition on heating of hsian-tsao polysaccharide solution was investigated by electron spin resonance (ESR), using nitroxide radicals (4-amino TEMPO) as labels that covalently attached to the carboxyl groups of uronic acid of the hsian-tsao polysaccharide chains. As indicated by the increased rotational correlation time ( τ c ) and broadening ESR resonance signals due to anisotropic effects, the mobility of the polymer chains became more restricted with reducing temperature and increasing glycerol concentration (0–80%). A change in anisotropic ratio ( p value) likely reflecting the molecular dissociation and conformational disordering of the polysaccharide was observed during heating at 40–50 °C, and being more remarkable as glycerol concentration increased. The increment in glycerol concentration resulted in a two-fold increase in activation energy of the conformational transition (from 17.93 to 35.15 kJ/mol).