Textural properties and morphology of soy 7S globulin-corn starch (amylose,amylopectin)

The texture properties (hardness, adhesiveness, cohesion, elasticity) of composite gels with different ratios (0:100, 6:94, 8:92, 10:90, 12:88, and 14:86, respectively) of soy 7S globulin to corn starch (amylose, amylopectin) were studied. Furthermore, the morphology and crystal structure of the mixed gels were investigated. The results showed: the addition of soy 7S globulin could weaken the hardness of corn starch (amylose, amylopectin) and increased the adhesiveness of corn amylose significantly (p < 0.05). Generally, when the additive amount of soy 7S globulin was 10%, the composite gels of soy 7S globulin and corn starch (amylose, amylopectin) appeared to have the best consistency, cohesion, and elasticity.     

Fine structure of amylopectin and relation with physicochemical properties of three coloured potato starches

In this study, yellow, red and purple potato starches were selected as the research objects to analyse the fine structure and the relation to the physicochemical properties. Enzymatic hydrolysis and high-performance anion-exchange chromatograph were employed to characterise the structure of clusters and φ, β-limit dextrins. The average degree of polymerisation of clusters from the yellow potato starch was larger (188.57) than in red (91.31) and purple (107.32) potato starch. The molar percentage of fingerprint B chains in yellow, red and purple potato amylopectin were 58.01%, 63.60% and 60.78%, respectively, while major part of short B chains were 15.92%, 17.16% and 16.49%, respectively. The yellow potato amylopectin showed the highest density of branches values indicated that it was more tightly branched. The Pearson correlation coefficients results indicated that the fine structure of amylopectin had significant effects on the physicochemical properties of potato starches, and we can better understanding the differences of the properties among the three potato starches by studying the amylopectin fine structure.     

Orthogonal-function spectrophotometry for the measurement of amylose and amylopectin contents

In this study, orthogonal-function spectrophotometry (OFS) was used for the first time in the determination of amylose and amylopectin contents. A six-point quadratic orthogonal polynomial (QOP) was chosen for amylose determination at an interval of 8 nm, and an inter-wavelength of 596 nm. For amylopectin determination, a ten-point QOP was selected with an interval of 22 nm and an inter-wavelength of 538 nm. OFS was more precise, with a standard deviation (SD) of 0.4–0.7 for both amylose and amylopectin content analyses. Dual-wavelength colorimetry (DWC) showed a SD of 1.3–2.5 and 3.8–4.6 for amylose and amylopectin content analyses, respectively. OFS has an acceptable recovery ratio and hence has an advantage over DWC in determining amylose and amylopectin concentration in solution without prior separation. OFS is an alternative method for the analysis of amylose and amylopectin content.     

Microstructural and physicochemical properties of heat-moisture treated waxy and normal starches

Starches from normal rice (21.72% amylose), waxy rice (1.64% amylose), normal corn (25.19% amylose), waxy corn (2.06% amylose), normal potato (28.97% amylose) and waxy potato (3.92% amylose) were heat-treated at 100 °C for 16 h at a moisture content of 25%. The effect of heat-moisture treatment (HMT) on morphology, structure, and physicochemical properties of those starches was investigated. The HMT did not change the size, shape, and surface characteristics of corn and potato starch granules, while surface change/partial gelatinization was found on the granules of rice starches. The X-ray diffraction pattern of normal and waxy potato starches was shifted from B- to C-type by HMT. The crystallinity of the starch samples, except waxy potato starch decreased on HMT. The viscosity profiles changed significantly with HMT. The treated starches, except the waxy potato starch, had higher pasting temperature and lower viscosity. The differences in viscosity values before and after HMT were more pronounced in normal starches than in waxy starches, whereas changes in the pasting temperature showed the reverse (waxy > normal). Shifts of the gelatinization temperature to higher values and gelatinization enthalpy to lower values as well as biphasic endotherms were found in treated starches. HMT increased enzyme digestibility of treated starches (except waxy corn starch); i.e., rapidly and slowly digestible starches increased, but resistant starch decreased. Although there was no absolute consistency on the data obtained from the three pairs of waxy and normal starches, in most cases the effects of HMT on normal starches were more pronounced than the corresponding waxy starches.     

盐对不同直链含量玉米淀粉理化特性及流变学特性的影响

分析了盐对不同直链含量玉米淀粉的理化特性及流变学特性的影响。结果表明,盐抑制了淀粉颗粒的膨胀,盐浓度越大,抑制作用越强。盐质量浓度为0 g/100 mL的蜡质淀粉和普通淀粉膨胀势在65℃到75℃迅速增加,2.0 g/100 mL时膨胀势在75℃到85℃迅速增加且幅度最小。蜡质淀粉和普通淀粉DSC图谱呈G峰和M2峰,高直链淀粉呈G峰。盐提高了凝胶化起始温度,蜡质淀粉从50.1℃增加到90.2℃,普通淀粉从56.6℃增加到99.6℃,高直链淀粉从98.8℃增加到105.7℃。盐也抑制了淀粉的糊化进程,盐浓度越大,糊化温度越高。普通淀粉的储存模量G',损耗模量G"和表观黏度η大于蜡质淀粉。普通淀粉和蜡质淀粉在低盐浓度(0.6g/100 mL)下的G'、G"和η值均大于高盐浓度(2.0 g/100 mL)。     

Some physical and nutritional characteristics of genetically modified potatoes varying in amylose/amylopectin ratios

Transgenically modified potatoes with a large spread in amylose/amylopectin ratios were analysed both as tubers and in the form of isolated starch. Different microscopic techniques were used to study starch granules and tuber tissue. Starch gelatinisation properties and recrystallisation of amylopectin and amylose were studied by differential scanning calorimetry. Starch bioavailability and resistant starch (RS) were evaluated using enzymatic in vitro procedures. Glycaemic indices (GI) were predicted from low molecular weight carbohydrates (LMWC) contents and the in vitro hydrolysis rate of the starch moiety. For many of the examined parameters, differences of varying magnitude were found between the potato lines, especially for high amylose lines. High amylose starch granules had irregular shapes and showed only a limited swelling. Moreover, contents of RS and recrystallised amylose were elevated. GI’s for the starch moiety were reduced, though elevated contents of LMWC caused a high over-all predicted GI.     

Physicochemical and rheological properties of modified rice amylose by dynamic high-pressure microfluidization

The effect of dynamic high-pressure microfluidization on physicochemical and rheological properties of rice amylose pastes were examined. The amylose dispersions were pressurized at 60, 100, 140, and 180 MPa. The microfluidization treated rice amylose showed elevated solubility, swelling power, and moisture absorbability. The retrogradability was significantly decreased with the pressure increase. Iodine blue value showed a significant increase at 60~140 MPa, while a slight decrease at 180 MPa. The rheological results indicated that native amylose was a non-Newtonian fluid and displayed pseudoplastic fluids characteristics. The amylose moved toward a Newtonian fluid behavior and its rheopexy decreased with the pressure increased.     

The importance of amylose and amylopectin fine structures for starch digestibility in cooked rice grains

Statistically and causally meaningful relationships are established between starch molecular structures (obtained by size-exclusion chromatography, proton NMR and multiple-angle laser light scattering) and digestibility of cooked rice grains (measured by in vitro digestion). Significant correlations are observed between starch digestion rate and molecular structural characteristics, including fine structures of the distributions of branch (chain) lengths in both amylose and amylopectin. The in vitro digestion rate tends to increase with longer amylose branches and smaller ratios of long amylopectin and long amylose branches to short amylopectin branches, although the statistical analyses show that further data are needed to establish this unambiguously. These new relationships between fine starch structural features and digestibility of cooked rice grains are mechanistically reasonable, but suggestive rather than statistically definitive.     

Effects of molecular characteristics of tea polysaccharide in green tea on glass transitions of potato amylose,amylopectin and their mixtures

Tea polysaccharide (TPS) is attracting more attention gradually in many fields due to its particular biological properties. To further elucidate the functions of TPS to starch-based foods, experiments were carried out using mixed amylose/amylopectin/TPS system as a model. The effects of TPS in green tea on the glass transition temperatures (Tgs) of the mixtures with different amylose/amylopectin ratios at low water contents were investigated using high-speed differential scanning calorimetry (Hyper-DSC). The results showed that the Tgs of amylose, amylopectin and their mixtures decrease with increasing concentration of TPS. It is suggested that the addition of TPS has plasticizing effects on the structures of amylose and amylopectin on the molecular level. Based on the molecular characteristics of TPS, the results in this study indicated that TPS is a homogeneous and spherical polymer with branch in solution, which can increase free volume and molecular movement of amylose and amylopectin chains. TPS can also produce greater electrostatic repulsion and decrease association among macromolecules, thereby resulting in the decrease of the Tgs of amylose, amylopectin and their mixtures.     

Relationship between the structure,physicochemical properties and in vitro digestibility of rice starches with different amylose contents

The in vitro digestibility and molecular and crystalline structures of rice starches (Long-grain, Arborio, Calrose, and Glutinous) differing in amylose content were investigated and the relationship between the structure and in vitro digestibility of starch was studied. Long-grain showed the highest amylose content (27.2%), whereas Glutinous showed the lowest amylose content (4.2%). Long-grain had the highest average amylopectin branch chain length (18.8) and proportion (8.7%) of long branch chains (DP ≥ 37), and the lowest proportion (26.9%) of short branch chains (DP 6–12). Among the non-waxy rice starches (Long-grain, Arborio, and Calrose), Calrose had the lowest average chain length (17.7) and the lowest proportion (7.1%) of long branch chains (DP ≥ 37). The relative crystallinity of rice starch followed the order: Glutinous (33.5%) > Calrose (31.4%) > Arborio (31.0%) > Long-grain (29.9%). Long-grain had the highest gelatinization temperature and the lowest gelatinization temperature range, whereas Glutinous showed the highest gelatinization temperature range and gelatinization enthalpy. Arborio had the highest melting enthalpy for amylose–lipid complex among the tested rice starches. Pasting temperature, setback, and final viscosity increased with increasing amylose content, whereas the peak viscosity and breakdown showed negative correlations with amylose content. The rapidly digestible starch (RDS) content of the tested rice starches followed the order: Glutinous (71.4%) > Calrose (52.2%) > Arborio (48.4%) > Long-grain (39.4%). Contrary to this, the slowly digestible starch (SDS) and resistant starch (RS) contents showed an opposite trend compared to RDS. Digestibility (RDS, SDS, and RS) of the rice starches was significantly correlated (p ≤ 0.05) with amylose content, proportions of DP 6–12 and DP 13–24, relative crystallinity, intensity ratio (of 1047 cm⁻¹ to 1022 cm⁻¹ from Fourier transform infrared spectroscopy), swelling factor, amylose leaching, onset temperature of gelatinization, gelatinization temperature range, gelatinization enthalpy, pasting temperature, peak viscosity, breakdown, setback, and final viscosity.     

A novel triple‐wavelength colorimetric method for measuring amylose and amylopectin contents

A novel triple‐wavelength colorimetry based on the principle of iodine binding was developed to determine amylose and amylopectin contents. Detection wavelengths of different starch material were different for each method. Comparative trials were carried out by both single‐ and dual‐wavelength colorimetry. We found that single‐wavelength colorimetry could only be used to evaluate amylose content. Correlation coefficient of standard curves for amylopectin content determination was improved by increase of detection wavelength numbers. The precision and recovery coefficient was also improved by triple‐wavelength colorimetry compared to single‐ and dual‐wavelength colorimetry. Percent amylose of cassava, potato, and high‐amylose maize determined by triple‐wavelength were 19.3, 21.8, and 42.3%, respectively, and percent amylopectin were 78.9, 76.9, and 54.5%, respectively. This developed triple‐wavelength colorimetry could provide accurate data for evaluating amylose content and have potential for amylopectin content detection.     

甘薯块根膨大过程中质构特性和淀粉直/支比的研究

甘薯块根膨大过程中质构特性和淀粉组分的变化对甘薯的品质和用途有着重要影响。本研究选取3种甘薯类型和4个时期,通过质地多面分析法(TPA)和双波长碘比色法,分析其质构特性和淀粉直链淀粉和支链淀粉比值(淀粉直/支比)随块根膨大的变化规律。结果表明,甘薯淀粉直/支比在扦插后80天开始下降,至扦插后110天达到谷值,之后小幅回升;整体上,甘薯扦插后的天数与淀粉直/支比、内聚性和弹性呈显著负相关(r =-0.390, r= -0.367, P <0.05;r= -0.634, P <0.01);与硬度呈显著正相关(r= 0.590, P <0.01)。淀粉直/支比与块根的内聚性、弹性和咀嚼性呈显著正相关(r =0.368, P <0.05; r= 0.463, r= 0.642, P <0.01);综合分析发现,扦插后80~110天（块根膨大高峰期至膨大后期）收获的甘薯适合水果型(生食型)甘薯的开发。     

The physicochemical and binder properties of starch from Persea americana Miller (Lauraceae)

Avocado starch was extracted from the kernels of the fruit Persea americana Miller (Fam. Lauraceae) and evaluated for its potential as an alternative to maize starch as a pharmaceutical excipient. Its physicochemical and thermal properties were evaluated and compared with those of maize starch. Granules prepared with avocado and maize starch pastes as binder were evaluated for their flow, friability and compaction characteristics. The average yield of starch extracted from the fresh kernels of P. americana was 20.5 ± 0.55% w/w. The scanning electron micrograph (SEM) showed that avocado starch has two characteristic granule shapes; triangular and circular both having an approximate equal distribution. The triangular shaped granules are larger (28 to 32 µm) than the circular (6 to 9 µm). The foaming capacity of avocado starch was 19.05 ± 0.6%, its swelling, moisture uptake and paste clarity were generally lower than that of the maize starch. Avocado starch gel exhibited an extent of syneresis after freeze–thaw that increased cumulatively with increase in number of freeze–thaw cycles. The glass transition (T_g) and gelatinisation temperatures for avocado starch were higher than that of maize starch. The melting temperatures (T_m), ash value, as well as the various densities of avocado starch showed similarities with those of maize starch. The granules prepared with avocado starch pastes as binder showed superior compactibility and mechanical strength to those of maize starch but with similar flow characteristics. Avocado starch generally showed distinct physicochemical and binder properties with some similarities to the standard maize starch.     

3种栗属坚果淀粉的结构及其理化特性

以我国南北方种植的3种栗属坚果(板栗、锥栗和日本栗)为原料提取淀粉,通过扫描电镜(SEM)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)、快速黏度仪(RVA)等仪器和方法,研究14个品种淀粉的颗粒结构和理化特性的差异,并对其进行相关性分析。结果表明:栗属坚果的直链淀粉含量差异显著,淀粉颗粒形态较为复杂,颗粒表面光滑完整;淀粉均属于C型晶体,结晶度为20.43%～25.63%,淀粉的冻融稳定性好。不同品种淀粉的颗粒结构和理化特性之间存在多种相关性,说明直链淀粉含量和结晶结构影响淀粉的理化性质。     

Effects of annealing on the physicochemical properties and enzymatic susceptibility of rice starches with different amylose contents

This study investigated the effects of annealing (ANN) on the properties of rice starches with high, medium and low-amylose contents. The starches were heated with excess water at 45 °C, 50 °C and 55 °C for 16 h. The swelling power, solubility, pasting properties, enzymatic susceptibility, morphology and X-ray crystallinity of the starches were evaluated. Annealing reduced the swelling power and solubility of the starches. ANN at 55 °C increased the pasting temperature and decreased the peak viscosity of the high-amylose rice starch. However, annealing decreased the peak viscosity of the low-amylose starch. The annealed rice starches presented a lower final viscosity and setback than did the native starches, with the exception of the low-amylose starch, which showed an increase in setback. Annealing increased the starches’ susceptibilities to α-amylase and promoted a reduction in their relative crystallinity.     

Effects of cross-linking and low molecular amylose on pasting characteristics of waxy corn starch

The action of amylose within the granule of normal corn starch is investigated by changes in pasting characteristics of waxy corn starch in a Rapid Visco Analyzer (RVA), using addition of soluble amylose (DP = 18) and cross-linking with epichlorohydrin. Although waxy corn starch, containing no amylose, did not show an effect of addition of amylose on pasting characteristics, by cross-linking with epichlorohydrin, the pasting peak viscosity and breakdown were greatly enhanced and set-back (viscosity increased in the cooling process after gelatinization) was generated. The cross-linking depressed the disintegration of starch granules in the swelling process, with amylose interaction, resulting in RVA pasting characteristics similar to those seen with normal corn starch containing amylose. Set-back was essentially caused by rearrangement among modified amylopectins. Addition of sodium dodecyl sulfate (SDS) to the RVA more efficiently enhanced the effect. This indicated that amylose in normal corn starch interacts with amylopectin through locally strong linkages.     

Chemical compositions,fine structure and physicochemical properties of kudzu (Pueraria lobata) starches from different regions

Three commercial kudzu starches from Vietnam, Japan and Korea were used to determine chemical compositions, isoflavone compounds, fine structure and physicochemical properties. The kudzu starch from Vietnam had polygonal granules, whereas the kudzu starches from Japan and Korea contained both polygonal and spherical granules. Total protein, lipid, ash and phosphorus contents present in these kudzu starches were less than 1% (starch basis). The kudzu starch from Vietnam and Korea contained both daidzein and daidzin, whereas the kudzu starch from Japan had only daidzein. These starches had similar actual amylose contents (22.2–22.9%). However, λ_max, blue value and apparent amylose contents of the kudzu starch from Vietnam were lower than those from Japan and Korea. Amylose molecules of the kudzu starch from Vietnam had the largest average degree of polymerization (DP_n) and number of chains (NC), followed by the kudzu starches from Japan and Korea. Amylopectin molecules of the kudzu starch from Vietnam also had the largest DP_n and NC, followed by the kudzu starches from Korea and Japan. X-ray diffraction patterns of the kudzu starches from Vietnam, Japan and Korea were A-type, C-type and B-type, respectively. The kudzu starch from Vietnam was found to have the specific characteristics such as significantly high gelatinization temperature, transition enthalpy and degree of crystallinity as compared to the kudzu starch from Korea and Japan.