Chemical Structure of Barley Starches. I. A Study of the Properties of the Amylose and Amylopectin from Barley Starches Showing a wide Variation in Brabender Cooking Viscosity Curves

The starches from two barley varieties showing extreme differences in cooking viscosity were fractionated. The amylose and amylopectin from the variety showing a high cooking viscosity, Nupana, are larger than those from the low cooking viscosity variety, Titan. Although no substantial differences were observed in the yields and chain length in the debranched amylopectins, there is evidence that the Titan amylopectin branches contain a block to β-amylase action. This would account for the low beta-limit on the Titan amylopectin. The breaking of H-bonding on heating should allow the starch fractions more freedom to expand and accounts for the fact that the starch having the largest fractions exhibits the greatest viscosity. The molecular size of amylose as estimated by the use of the polarograph suggests that the use of limiting viscosity for this purpose should be used with caution.     

Conformational Contributions of Amylose and Amylopectin to the Structural Properties of Starches from Various Sources

Six starches of different amylose content were studied by static light scattering from very dilute aqueous solutions at 20°C. Reproducible results were obtained after submitting the solutions to a controlled autoclaving step where the solutions were heated up to 135-155°C. Amylose rich starches exhibited significantly different angular dependences from those with low amylose content. The high experimental accuracy of the angular dependences allowed separate determination of the molar masses Mw and radii of gyration Rg for both components in the mixture. Molar masses of 60-10⁶ to 110- 10⁶ and radii around 220nm were found for the amylopectins from the various starches. Unexpectedly high molar masses between 450-10³ and 2.5-10⁶ were found for the amylose components but only low radii of gyration. Comparison with synthetic amyloses indicate strong intra and intermolecular aggregation in the form of laterally (side-by-side) aligned chains which could contain up to 35 amylose chains. The possibility of a quantitative determination of the degree of branching via the shrinking factor g (=Rg²Ap/Rg²Am I at the same molar mass) is discussed at some length.     

稻米淀粉的理化特性研究Ⅱ稻米直链淀粉和支链淀粉的理化特性

本文研究了稻米淀粉不同级分的理化特性及稻米类型对各级分理化特性的影响。结果表明 :稻米淀粉级分的理化特性有较大差异 ,稻米类型对各级分理化特性有影响。直链淀粉的碘结合力为 19.99～2 0 .31mgI2 /g淀粉 ,支链淀粉为 0 .0 6～ 0 .0 95mgI2 /g淀粉 。直链淀粉的碘兰值为 0 .2 0～ 0 .2 5OD/0 .1g淀粉 ,以籼稻直链淀粉的碘兰值较大 ;支链淀粉碘兰值为 0 .0 3～ 0 .10OD/0 .1g淀粉 。直链淀粉的特性粘度为 5 0～ 15 0mL/g ,以粳稻较大 ;支链淀粉的特性粘度为 5 0 0～ 95 0mL/g ,以糯稻最大 ,籼稻最小。直链淀粉与碘复合物的可见光最大吸收波长为 6 0 0～ 6 2 0nm ,支链淀粉为 5 2 0～ 5 40nm ,品种差异较小。分离纯化后直链淀粉的结晶度为 2 3%～ 2 5 % ,支链淀粉则无晶体结构 ,结晶度的品种差异较小。稻米支链淀粉的分子量为 4 7× 10 6 (籼稻 )～ 2 35× 10 6 (糯稻 ) ,直链淀粉的分子量为 0 .4 4× 10 6 (籼稻 )～ 1.6 2× 10 6 (粳稻 )。     

Effect of Gene Dosage at High Amylose Loci on the Properties of the Amylopectin Fractions of the Starches

The effect of gene dosage at the amylose-extender (ae) locus of maize and the rigosus-a (r_a) locus of peas on the amylopectin fraction of endosperm and cotyledon starch were examined. Amylopectin fractions were isolated by gel filtration, butanol complexing and a combination of the two methods. In general, increasing doses of the recessive allele at either locus resulted in amylopectin fractions with iodine spectra with absorption maxima at higher wavelengths and greater absorptivity. Starches from endosperm of differing ae dosage but homozygous waxy were found to contain no amylose by gel filtration. By debranching with pullulanase, these starches were shown to have increasing average chain length with increasing ae dosage. Additional data suggested that increasing dosage at the ae locus (regardless of the genotype at the waxy locus) or the r_a locus resulted in amylopectin with increasing linearity. In addition, short chained amylose (approximately 100 glucose units) was observed in all ae genotypes in a homozygous Waxy background and all r_a genotypes.     

Extrusion of Rice,Bean and Corn Starches: Extrudate Structure and Molecular Changes in Amylose and Amylopectin

The objective of this study was to evaluate the effects of starch source and amylose content on the expansion ratio, density, and texture of expanded extrudates, as well as to investigate the structural and molecular changes that occur in starch granules as a function of extrusion. The starches employed were rice starches (8%, 20%, and 32% amylose), carioca bean starch (35% amylose), and Hylon V^® corn starch (55% amylose). The extrudates from rice starches containing 20% and 32% amylose exhibited the highest expansion ratio, while, extrudates from Hylon V^® corn starch containing 55% amylose exhibited the lowest expansion ratio. The hardness values of the extrudates with 55% amylose were twice those of the extrudates with 20%, 32%, and 35% amylose. An additional finding was that although the amylopectin promoted the expansion of the gelatinized starch matrix, it failed to strengthen and sustain the walls of the extrudate bubbles during expansion.     

Effect of Amylopectin Structure on the Gelatinization and Pasting Properties of Selected Yam (Dioscorea spp.) Starches

This study was aimed at elucidating the decisive structural parameters of amylopectin which govern the gelatinization or pasting behavior of yam starch dispersions, exemplified with four selected yam starches from Dioscorea alata and D. batatas with very similar amylose contents (32.2–34.6%). The results indicated that the yam amylopectins examined showed an average degree of polymerization (DP) of 3469–4474 anhydroglucose units (AGU), average chain length (CL) of 18.8–28.5 AGU, average exterior CL (ECL) of 11.8–16.4 AGU, average interior CL (ICL) of 6.0–11.1 AGU, and a noticeable proportion of extralong (> 100 AGU) and long (40–100 AGU) chains that gave the chain ratio r_(el+l)/s (the weight ratio of extralong and long chains to short chains) of 0.88–1.40. Generally, the yam amylopectin with a lower DP and NC possessed a greater CL, ECL, ICL, and r_(el+l)/s, associating with a higher blue value (BV) and maximal wavelength (λ_max) for their complexes with iodine. D. alata amylopectins exhibited a lower DP, longer chain lengths and greater r_(el+l)/s than the D. batata amylopectins. Statistically, r_(el+l)/s was decisive for the BV and λ_max; while CL and phosphate content were crucial for the gelatinization peak temperature and pasting viscosities of the yam starches examined. The role of swelling power or the volume fraction of dispersed remnants instead in governing the pasting viscosity was also mathematically explored.     

颗粒冷水可溶高直链玉米淀粉的制备及特性研究

以高直链玉米淀粉为原料,采用乙醇-碱法和羟丙基醚化法结合,研究不同碱添加量、环氧丙烷添加量、反应时间、反应温度下淀粉的冷水溶解度和羟丙基含量的变化规律。结果发现:随碱添加量的增加,淀粉颗粒的溶解度先上升后降低,羟丙基含量随碱添加量的增加而增加;随环氧丙烷添加量的增加,溶解度呈现先升高后降低的趋势,羟丙基含量随环氧丙烷添加量的增加出现先升高后降低的趋势;随反应时间的延长,溶解度先升高后略有降低,羟丙基含量随反应时间的增加而增加;随反应温度的增加,溶解度先升高再降低,羟丙基含量随温度的升高先增加后略有下降。对制得的不同溶解度下颗粒冷水可溶淀粉糊的透明度研究发现,随着淀粉溶解度的增大,淀粉糊透明度显著提高。扫描电镜观察冷水可溶淀粉的颗粒形态保持完整,但表面出现凹陷。X射线衍射结果显示:冷水可溶淀粉颗粒的晶型从高直链淀粉的"B"型结晶变为"V"型,且尖峰衍射峰消失,全部变为弥散特征峰。     

Studies on the Structure of Pea Starches. Part 3: Amylopectin of Smooth Pea Starch

β-Limit dextrins were isolated from smooth pea starch. It was shown by gel chromatography that the sample contained smaller limit dextrins with a degree of polymerization (D.P.) of 40–4000 in addition to high-molecular-weight material. The smooth pea starch and the β-limit dextrins were hydrolysed by the α-amylase of B. amyloliquefaciens and the molecular weight distribution of the reaction mixtures was analysed on Sepharose CL 6B. Initially the reaction was fast, but at later stages branched dextrins with 10–60 were only very slowly hydrolysed further. In addition, linear dextrins with d.p. 2–10 were formed continously. Based on the branched dextrins produced from the β-limit dextrins a model of the structure of the amylopectin component in smooth pea starch is suggested, in which clusters of defined sizes are regularly interconnected.     

葛根直链淀粉和支链淀粉分离纯化的研究

用重结晶的方法对葛根淀粉中直链淀粉和支链淀粉组分进行分离和纯化，并利用碘亲和力测定，凝胶过滤层析，Ｘ－射线衍射等方法对产品的纯度进行了鉴定。结果表明通过重结晶８次可得到完全纯化的葛根直链淀粉；反复３次加入正丁醇去除残留的直链淀粉可得到完全纯化的葛根支链淀粉。     

Structure and Viscoelastic Properties of Starches Separated from Different Legumes

A comparison between the morphological, structural, thermal and viscoelastic properties of starches separated from pigeon pea, chickpea, field pea, kidney bean and blackgram was made. The shape of the starch granules in the different legumes varied from oval to elliptical or spherical. X-ray diffraction of the legume starches indicated a typical C-pattern (mixture of A- and B-type). Granules of blackgram and pigeon pea starch had a higher degree of crystallinity than those of field pea and kidney bean starches. Apparent amylose content of field pea, kidney bean, chickpea, blackgram and pigeon pea starch was 37.9%, 36.0%, 34.4-35.5%, 32.9-35.6% and 31.8%, respectively. Distribution of isoamylase-branched materials among the starches revealed that the proportions of long and short side chains of amylopectin ranged between 13.6-18.5% and 41.7-46.5%, respectively. Field pea and kidney bean starch had the highest apparent amylose content and the lowest amount of long side chains of amylopectin, respectively. Blackgram and pigeon pea starch possessed higher proportions of both long and short side chains of amylopectin than field pea and chickpea starches. The onset, peak and conclusion temperatures of gelatinization (T_o T_p and T_c, respectively) were determined by differential scanning calorimetry. T_o and T_c ranged from 59.3 to 77.3°C, 66.8 to 79.6°C, 55.4 to 67.6°C and 68.3 to 69.3°C, respectively, for chickpea, blackgram, field pea and kidney bean starch. The enthalpy of gelatinization (ΔH_gel) of field pea, kidney bean, chickpea, blackgram and pigeon pea starches was 3.6, 3.0, 2.6-4.2, 1.6-1.7 and 2.6 J/g, respectively. Pastes of blackgram and pigeon pea starches showed lower storage and loss shear moduli G′ than field pea, kidney bean and chickpea starches. The changes in moduli during 10 h at 10°C revealed retrogradation in the order of: field pea> kidney bean> chickpea> blackgram> pigeon pea starch. In blackgram and pigeon pea starches, the lower proportion of amylose plus intermediate fraction and higher proportion of short and long side chains of amylopectin are considered responsible for the higher crystallinity, gelatinization temperature and enthalpy of gelatinization.     

Granular Structure and Physicochemical Properties of Starches from Amaranth Grain

The granular structure and physicochemical properties of starches isolated from grain amaranth cultivar K112 (Amaranthus cruentus L.) were studied in this study. Detailed physical and chemical analyses were performed by determining the granular morphology, crystallinity, particle size, thermal characteristics, blue value, enzyme susceptibility, and pasting properties. Results showed polygon-shaped A. cruentus L. K112 starch granules. The average diameter was 1.38 μm, in which half of the diameter was <2.91 μm. An A-type X-ray diffraction pattern was revealed with intense peaks of 15.2°, 17.5°, and 23.2°. The peak viscosity was 181 BU and the breakdown value was 2 BU. Amaranth starch obtained the highest pasting temperature (70.7°C) and enzymatic digestibility (absorbance value = 0.41 ± 0.013) compared with corn, cassava, and sweet potato starches.     

An SEC−MALLS Study of Molecular Features of Water‐soluble Amylopectin and Amylose of Tef [Eragrostis tef (Zucc.) Trotter] Starches

The molecular features of five tef starches along with those of commercial normal maize starch were investigated by size‐exclusion chromatography with multi‐angle laser light scattering‐differential refractive index detection (SEC/MALLS‐DRI) after solubilization in water by cooking in a household pressure cooker. The weight‐average molar mass ( ) and weight‐average root‐mean square radius of gyration (<R_g>_w) of the amylopectin (AP) of tef starches ranged from 10.1×10⁷ g/mol (156 nm) to 16.5×10⁷ g/mol (205 nm) with a mean of 13.9×10⁷ g/mol (186 nm). The AP of the tef starches was considerably smaller than that of maize starch ( = 19.6×10⁷ g/mol, <R_g>_w = 207 nm). These considerably smaller AP molecules in tef starches were most probably responsible for the low paste viscosity of tef starches as compared to maize starch. In most tef starches, the polydispersity index (PI) of the AP was broader than that of the AP of maize starch. The intermediate fraction (IN) 1.0−1.6, mean = 1.1) of most tef starches were similar to those of the IN of maize starch. The amylose (AM) (range 1.5×10⁶−3.0×10⁶ g/mol, mean = 2.2×10⁶ g/mol) and size (range 176−214 nm, mean = 191 nm) of most tef starches was also apparently similar to that of the maize starch ( = 2.3×10⁶ g/mol, <R_g>_w = 193 nm), but the polymer distribution was narrower. The AM−iodine complex of the tef starches had a λ_max range of 611−679 nm and the absorption shifted toward longer wavelengths by 8−14 nm as compared to the maize starch AM−iodine complex. The blue value (absorption at λ_max) for 1 mg/mL of tef AM had a range of 2.3−2.8 (mean = 2.5), whereas for the maize starch, the mean was 2.2. The branched nature of tef starches was also investigated by debranching with isoamylase and determination of chain lengths (DP_n) of the branches by size exclusion chromatography with refractive index detector (SEC‐RI). The AP in tef starches had a polymodal distribution with a periodicity similar to that of cereal starches. The branches had DP_n values of A = 11, B1 = 16, B2 = 46 (range 46−47), B3 = 70 (range 69−72) and B4 = 118 (range 113−123). The outer (A + B1) chains were shorter than those of maize starch AP with abundance (74%, w/w) only slightly less than that of the maize starch (75%, w/w). The slow rate of retrogradation, the slightly lower percent crystallinity, the lower gelatinization temperatures and the lower gelatinization enthalpy observed for tef starches (as compared to maize starch) are probably related to the shorter outer (A + B1) chain lengths of their amylopectin molecules, and may be the foundation of the comparably good keeping quality of tef injera, the main staple in the Ethiopian diet.     

Investigation of the Physical and Chemical Properties of Banana Starches

Banana (Musa sp.) starch was isolated after steeping in 0.05N sodium hydroxide. The starch had a granule size of 20–60μ, a gelatinization temperature range of 74–83°C, and a B-type X-ray diffraction pattern. The Brabender viscoamylogram and the swelling pattern indicated a fairly restricted-swelling starch. The starch had low iodine affinity (ca 3.30%) and contained diesterified phosphate. During ripening, the amount of starch converted into reducing sugars and sucrose increased with degree of ripeness. Small granules were converted more rapidly than large granules. Other physical and chemical properties remained similar throughout ripening.     

A Study of the Internal Structure in Cassava and Rice Amylopectin

Cassava and rice amylopectins and their ϕ,β‐limit dextrins were debranched and the unit chain compositions were analyzed by gel permeation chromatography and high performance anion‐exchange chromatography. The content of amylose and super‐long amylopectin chains was 15.5‐15.6% and 0.8‐1.2% in cassava and 15.1‐18.7% and 3.4‐8.6% in rice starches, respectively. The internal unit chain profiles of the amylopectin samples were obtained from the ϕ,β‐limit dextrins. Short B‐chains were subdivided into a major group (BS_major) with a degree of polymerization (DP) of 8‐25 and a minor group of “fingerprint” B‐chains (B_fp) with DP 3‐7. Cassava and rice amylopectins possessed different amounts and patterns of B_fp‐chains. The rice samples contained higher amounts of B_fp‐chains, which suggested larger size of its clusters when compared with cassava. The content of the shortest “fingerprint” A‐chains (A_fp) was also variable, especially between the rice cultivars. The position of the internal chains in the original amylopectin chain profile was traced. The reconstructed B‐chain profiles fitted well with the original profiles. This implied that most of the B‐chains carried external chain segments of similar lengths, which corresponded to the experimentally measured average length.     

Corn Starch (α1,4-α1,6) Glucopolysaccharides - Correlation Between Amylose: Amylopectin Ratios and Physical Properties of the Grains

The starch components from corn inbreads and hybrids, mature seeds of commercial interest, were fractionated according to their branching degree. The amount and structural properties of them was determined, allowing a better definition of the polysaccharides present in each fraction. The methodology used allowed the visualization of the introduction of some traits if they result in a structural change of the starch components. It is, therefore, suggested that it is possible to predict the endosperm type related to hardness. A linear correspondence was obtained between amylose % and % of endosperm type floury or horny.     

Chemical and Enzymatic Modifications of the Pasting Properties of Legume Starches

Refined legume starches were evaluated for their Brabender Visco/Amylograph properties in their native form and after chemical and enzymatic pretreatment during incubation for 20 h at room temperature. Although exhibiting the characteristic restricted paste viscosities of legume starches, native lentil starch showed much higher viscosity parameters than navy bean starch while field pea starch had very low, stable viscosities. Pretreatments with mineral acids, alkali or enzymes failed to significantly alter the amylographs of the 8% slurries (w/v). Removal of surface lipids on the refined starch granules with propanol/water (3:1 v/v) or chloroform/methanol (2:1 v/v) increased paste viscosities substantially, as did the complexation of the starches with palmitic acid or glyceryl monopalmitate. None of the treatments resulted in complete dissolution of the starch granules and the modified starches showed no improvement in gel syneresis during storage.     

支链聚合度对菠萝蜜支链淀粉与月桂酸复合物理化特性的影响

为探究支链聚合度对支链淀粉-脂肪酸复合物糊化特性的影响,对5种支链聚合度不同的菠萝蜜种子支链淀粉（Jackfruit seed amylopectin, JFSA）与月桂酸复合物（M1ZY、M2ZY、M3ZY、M4ZY和M5ZY）的理化特性进行了测定并分析了这五种复合物糊化特征参数、重均聚合度（DPw）和复合指数（CI）的相关性。结果表明:随着支链聚合度升高,形成的菠萝蜜种子支链淀粉-月桂酸复合物的复合指数显著增加（P<0.05）,由23.27%（M1ZY）提高到35.95%（M5ZY）;五种复合物的脱水收缩程度、水溶性与油溶性,以及膨胀度、溶解度值均明显增加;五种复合物的糊化特征参数值有显著差异,其峰值黏度（PV）、谷值黏度（TV）、最终黏度（FV）随支链聚合度聚合度的增加而升高,但崩解值（BkD）、回生值（StB）降低;Pearson相关分析表明,支链淀粉的DPw与复合物的TV、CI呈显著正相关（r=0.887,0.949,P<0.05）。支链聚合度是影响菠萝蜜种子支链淀粉-月桂酸复合物理化特性的重要因素。     

山西不同品种谷子淀粉的理化特性研究

从谷子主产区山西省选取8个具有代表性的谷子栽培品种作为供试材料,分析研究了其淀粉的颗粒形态及粒径大小、直链淀粉含量、碘蓝值与淀粉糊的透光率、冻融稳定性、糊化特性、溶解度与膨胀度及凝沉特性等理化性状。结果表明：小米淀粉颗粒均为单粒,外形规整,多数为多角形,少数为卵圆形,具有清晰可见的偏光十字,不同品种间淀粉颗粒形态差异明显。小米淀粉小颗粒的粒径为0.42~2.25 μm,大颗粒的粒径为3.42~29.26 μm,小米淀粉的粒径分布特征呈现出“三峰”型。8个品种的直链淀粉含量变幅为2.22~17.96%,碘蓝值变幅为0.586~0.872,透光率变幅为2.4~29.2%,析水率变幅为3.67~49.85%,糊化温度变幅为67.6~78.8 ℃,各品种间具有显著差异。此外,各品种淀粉的糊化特性、溶解度、膨胀势及淀粉糊的凝沉特性也有着明显的差异。因此,应根据不同的加工目的采用相适宜的品种。     

Studies on New Starches. Part 2. A Study of the Properties of Four Varieties of Mucuna Bean (Stizolobium)

The starches of the four varieties of Mucuna that have been studied are formed by granules of different sizes and rounded shapes. The average affinity for iodine is 5.60% and the amylose content is not very high. The values of the restricted swelling power and solubility and the slow and progressive solubilization in DMSO suggest a very homogeneous structure, with strong linking forces and a high degree of association inside the granules. The Brabender viscosity curves are very similar to those of the starches with artificially crossed linkages. These properties give the Mucuna bean starches very useful technological applications.