Oxidation of Maize and Rice Starches Using Sodium Chlorite Along with Formaldehyde

Maize and rice starches were independently oxidized with sodium chlorite in absence and presence of formaldehyde. The treatment was carried out under different conditions including sodium chlorite and formaldehyde concentrations and duration. Since the treatment involves degradation of starch via oxidation, the treated starch samples were monitored for carboxyl and carbonyl contents as well as apparent viscosity at different rates of shear. Results obtained indicated that with both starches the percent chlorite decomposed increases as the formaldehyde concentration increases within the range studied (0.0–0.3 g/100 starch). The same holds true for the duration of oxidation (15–90min). The apparent viscosity of starch before and after oxidation decreases as the rate of shear increases. Maize starch is more susceptible to oxidation than rice starch. When applied as sizing agents for cotton textiles oxidized starches derived from maize and rice starch display better performance than the unoxidized starch but with the superiority of the sizeability and desizeability of oxidized maize starch.     

Preparation and Characterization of Starch Acetate

Acetylation of native hydrolyzed and oxidized, maize starch has been studied. The different factors affecting acetylation process were investigated. These factors include liquor ratio, acetic anhydride, perchloric acid concentration, reaction time and temperature. Also investigated were characterization and application of the acetylated starches in textile warp sizing. The acetyl content increases to reach a maximum and then decreases on increasing either liquor ratio or perchloric acid concentration. Also it increases with increasing acetic anhydride concentration within the range examined whereas the actylation reaction efficiency % decreases. Hydrolysis of starch prior acetylation inhances the susceptibility of the starch towards acetylation whereas oxidation do the reverse. The solubility of acetylated starches derived from hydrolyzed or oxidized starches increases more than that of acetylated native starch. The solubility depends on the extent of acetylation and of the modification prior acetylation. Acetylation of starch improves its sizeability of cotton yarns.     

Comparative Acid Modification of Various Starches

Eight starches (maize, sorghum, finger millet, waxy and nonwaxy rice, chick pea, tapioca and potato) were acid modified with 0.5N HCl at 50°C. Alkali fluidity number (AFN) increased progressively with time of modification, and was highest in cereal followed by root, legume, and tuber starches. However, reduction in the number average molecular weight (M̄_n) was in the reverse order. Potato starch had the highest M̄_n, among the nonwaxy native starches and showed the greatest fall upon modification, whereas cereal starches had the least M̄_n in native form and showed the least fall. In fact, there was a clear proportionality between the M̄_n, of native starch and the extent of its hydrolysis under any given set of conditions. This relationship could be expressed by two intersecting lines, one for grains and one for root and tuber starches. When acid modified starches were recovered and dried without neutralization, hydrolysis still continued strongly in potato starch and slightly in tapioca, finger millet and sorghum starches. Other starches showed no change.     

Tailoring a New Sizing Agent via Structural Modification of Pregelled Starch Molecules Part 1: Carboxymethylation and Grafting

Pregelled starch (PS) was subjected to acid hydrolysis using phosphoric acid to prepare pregelled starches having different molecular sizes. The degraded pregelled starches were carboxymethylated at different reaction times. The carboxymethyl derivatives were grafted with either methacrylamide (MAam) or methacrylonitrile (MAN) as vinyl monomers using ceric ammonium nitrate (CAN) as initiator. Suitability of the new graft derivatives of pregelled starch as sizing agent of cotton yarns was studied. It is shown by the data that the extent of carboxymethylation, expressed as carboxyl content, increases by increasing the extent of hydrolysis and reaction time. Furthermore, the graft yield, expressed as mmol MAam or MAN monomer/100 g graft copolymer (grafted carboxymethylated pregelled starch or grafted carboxymethylated hydrolyzed pregelled starch) increases with increasing extent of carboxymethylation and degree of hydrolysis and follows the order: MAam > MAN. In addition cotton yarns sized with grafted carboxymethylated hydrolyzed pregelled starch – irrespective of the grafting monomer used – have better mechanical properties (tensile strength, elongation at break, and abrasion resistance) than hydrolyzed pregelled starches, carboxymethylated pregelled starch and carboxymethylated hydrolyzed pregelled starches.     

Evaluation of Some Starch Derivatives Containing Amide Groups as Flocculants

Three types of starch derivatives namely poly(acrylamide)‐starch graft copolymer, carbamoylethylated starch, and starch carbamate were prepared and evaluated as flocculants. Native and hydrolyzed maize starches were used as parent materials for these derivatives. The flocculation was followed by monitoring transmission % and weight removal %. The different factors affecting flocculation were studied. These factors include: (a) flocculant dose, (b) pH of the flocculation medium and (c) starch derivatives type, molar mass and nitrogen content. The flocculation efficiency of the three starch derivatives follows the order: poIy(acryIamide)‐starch graft copoIymer > carbamoylethylated starch > starch carbamate. The flocculation efficiency increases on increasing the nitrogen content and/or decreasing the molar mass of the flocculant. The flocculation efficiency of various flocculants at pH 6 is higher than at pH 8. The poIy(acryIamide)‐ starch graft copoIymer based on H₃‐starch has a higher flocculation efficiency than polyacryIamide.     

Comparative Studies on Some Physico-chemical, Thermal, Morphological, and Pasting Properties of Acid-thinned Jicama and Maize Starches

Comparative studies on acid hydrolysis of jicama and maize starch were carried out using concentrations of hydrochloric acid of 1.5%, 3.0%, and 4.5% (w/v), for 3 and 6 h, at 40°C. Native maize and jicama starches showed important morphological, thermal, and structural differences from those of tubers and cereals which potentially offer diverse industrial applications. Jicama starch showed low amylose content (12%) and small size of starch granules. Due to these characteristics, jicama starch was more susceptible to degradation during hydrolysis process than maize starch. Under the experimental conditions employed, the acid degradation was not particularly severe, as shown by scanning electronic microscopy analysis which showed small degraded zones and similar X-ray patterns in both starches. However, jicama starch was more susceptible to acid hydrolysis than maize starch, as revealed by the considerable increase in water solubility index, damaged starch, and crystallinity values. Also, the higher susceptibility of jicama starch than maize starch to the hydrolysis conditions was reflected in the sugar content release during hydrolysis. The relative crystallinity of hydrolyzed maize starches decreased during hydrolysis, while those of hydrolyzed jicama starches increased attributable to the lower amylose content of jicama starch in relation to maize starch. Maize and jicama hydrolyzed starches showed low viscosity values with relation to their native starch counterparts. However, native jicama starch showed lower viscosity values than maize starch, suggesting a lower internal stability of the starch granules during hydrolysis. Both native and hydrolyzed maize starches showed higher enthalpy, T _o, T _p, and T _c values than jicama starch and the broadening of the endotherms decreased during the hydrolysis of both starches.     

Synthesis and Characterization of Hypochlorite Oxidized Starches

Egyptian rice and maize starches were treated with sodium hypochlorite at different concentrations. The oxidized starches so obtained were monitored for carboxyl content and rheological properties. In addition, the extent and rate of the oxidation reaction was assessed by investigating the chlorine consumption. Results indicated that the extent and rate of oxidation of rice starch, expressed as chlorine consumption, are much higher than those of maize starch. The opposite holds true for the carboxyl content. Pastes of rice and maize starches before and after oxidation exhibit non-Newtonian thixotropic behaviour but their apparent viscosity decreases by increasing the hypochlorite concentration. At any event, however, the apparent viscosity of rice starch is substantially higher than that of maize starch. Storing the pastes for 24 h adversely affect the apparent viscosity particularly with oxidized starches prepared using higher hypochlorite concentrations.     

Inhibitory Effects of Green Tea Polyphenols on the Retrogradation of Starches from Different Botanical Sources

This paper aims at investigating the effects of green tea polyphenols (GTPs) on the retrogradation of potato, rice, and maize starches. Starch/GTPs mixing ratios were 2/0, 2/0.1, 2/0.2, and 2/0.3 (w/w) that equated with starch containing 0%, 5%, 10%, and 15% GTPs (based on starch weight), respectively. The analytic samples had a water–starch/GTPs ratio of 2:1. The effects of GTPs on the retrogradation of these starches were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The analysis of DSC indicates that the temperature and enthalpy of gelatinization of all the tested starches decreased as the GTPs level increased. After storage at 4 °C, retrogradation enthalpy (ΔH _ret) for potato starches with 5%, 10%, and 15% GTPs appeared after 10 days of storage, however ΔH _ret for rice and maize starches with 10% and 15% GTPs did not appear until storage of 20 days, and both the ΔH _ret and degree of retrogradation of the three starches significantly decreased with the increased level of GTPs. After 10 days of storage at 4 °C, the analysis of XRD shows that the intensity of X-ray diffraction peaks of potato starch gradually decreased with the concentration of GTPs increasing, and rice and maize starch gels with 10% and 15% GTPs had almost no recrystallization of the retrogradation. It is concluded that the addition of GTPs considerably inhibits the retrogradation of rice, maize, and potato starches.     

Chemical and Physical Characterisation of Grain Tef [Eragrostis tef (Zucc.) Trotter] Starch Granule Composition

Chemical and physical properties of starch granules isolated from five grain tef (Eragrostis tef) varieties were characterised and compared with those of maize starch. Endogenous starch lipids extracted with hot water‐saturated n‐butanol and total starch lipids extracted with n‐hexane after HCl hydrolysis were 7.8 mg/g (mean) and 8.9 mg/g (mean), respectively, slightly lower than in the maize starch granules. The starch phosphorus content (0.65 mg/g) was higher than that of maize starch but virtually the same as reported for rice starch. The starch granule‐swelling factor was lower than that of maize starch and extent of amylose leaching was higher. The starch X‐ray diffraction pattern was characteristic of A type starch with a mean crystallinity of 37%, apparently lower than the crystallinity of maize starch and more similar to that reported for rice and sorghum starches. The starch DSC gelatinisation temperature was high, like for other tropical cereals; T_o, T_p, T_c and ΔH were in the range 63.8—65.4, 70.2—71.3, 81.3—81.5 °C and 2.28—7.22 J/g, respectively. The lower swelling, apparently lower percentage crystallinity and lower DSC gelatinisation endotherms than maize starch suggest that the proportion of long amylopectin A chains in tef starch is smaller than in maize starch.     

Resistant starch and thermal,morphological and textural properties of heat‐moisture treated rice starches with high‐, medium‐ and low‐amylose content

This study investigated the effects of heat‐moisture treatment (HMT) on the resistant starch content and thermal, morphological, and textural properties of rice starches with high‐, medium‐ and low‐amylose content. The starches were adjusted to 15, 20 and 25% moisture levels and heated at 110°C for 1 h. The HMT increased the resistant starch content in all of the rice starches. HMT increased the onset temperature and the gelatinisation temperature range (T_finish–T_onset) and decreased the enthalpy of gelatinisation of rice starches with different amylose contents. This reduction increased with the increase in the moisture content of HMT. The morphology of rice starch granules was altered with the HMT; the granules presented more agglomerated surface. The HMT affected the textural parameters of rice starches; the high‐ and low‐amylose rice starches subjected to 15 and 20% HMT possessed higher gel hardness.     

Some Properties of Normal- and Waxy-Type Starches of Amaranthus hypochondriacus L

Starch granules were prepared from seeds of two types of Amaranthus hypochondriacus L., which are native to Nepal. The perisperm of one type of seeds stained reddish-brown with iodine solution and that of the other blue. Starch granules had round shape of about 1 μm diameter. X-ray diffraction diagrams were very similar each other and identical with the corresponding ones of rice and maize starches (A-type). Amylose contents and distribution of average chain-lengths of amylopectin were determined by gel filtration for isoamylase-debranched starches. Amylose content was about 14% and 0%, resp. Both types of Amaranthus starches had typical amylopectin nearly identical with those of rice and maize starches. Starch-granule digestibility by amylases and pasting characteristics of the Amaranthus starches were similar to those of fine starch granules.     

Molecular and physicochemical characterisation of starches from yam,cocoyam, cassava,sweet potato and ginger produced in the Ivory Coast

Granule sizes, macromolecular features and thermal and pasting properties of starches from seven tropical sources (Florido, Kponan and Esculenta yams, cocoyam, cassava, sweet potato and ginger) were compared with those of several well‐known cereal, legume and tuber starches. The aim of the study was to characterise some non‐conventional starches with a view to possibly marketing them. Amylose content varied from 148 mg g^?1 in Esculenta starch to 354 mg g^?1 in smooth pea starch. For total starches, weight‐average molar mass (M?_w) ranged between 0.94 × 10⁸ and 1.80 × 10⁸ g mol^?1 for potato and normal maize starches respectively. Gyration radius (R?_G) varied from 157 nm for ginger starch to 209 nm for normal maize starch. Gelatinisation enthalpy (ΔH) ranged between 9.8 and 20.7 J g^?1 for wheat and Florido starches respectively. Gelatinisation peak temperature (T_g) varied from 58.1 °C for wheat starch to 87.3 °C for ginger starch. Native starch granule mean diameter ranged between 5.1 and 44.5 µm for Esculenta and potato starches respectively. Cassava and potato starches had the highest swelling power and dispersed volume fraction at all treatment temperatures, while ginger starch had the lowest. Cocoyam starch had the highest and ginger starch the lowest solubility at 85 and 95 °C. Cassava starch was the most stable under cold storage conditions. Roots and tubers such as ginger and cassava produced in the Ivory Coast are new sources of starches with very interesting properties. Thus these starches could be isolated on an industrial level in order to market them. Copyright © 2007 Society of Chemical Industry     

Effect of Heat‐Moisture Treatment on Structural and Thermal Properties of Rice Starches Differing in Amylose Content

Starches from glutinous rice (1.4% amylose), Jasmine rice (15.0% amylose) and Chiang rice (20.2% amylose) were exposed to heat‐moisture treatment (HMT) at 100 °C for 16 h and at different moisture levels (18, 21, 24 and 27%). The effect of heat‐moisture treatment on structural and thermal properties of these three rice starches was investigated. The HMT did not change the size, shape and surface characteristics of rice starch granules. The A‐type crystalline pattern of rice starches remained unchanged after HMT. The relative crystallinity (RC) and the ratio of short‐range molecular order to amorphous (RSA) of heat‐moisture treated glutinous and Jasmine rice starches decreased with increasing moisture level of the treatments. In contrast, the RC of the treated Chiang rice starch remained practically unchanged. A peak of crystalline V‐amylose‐lipid complexes was clearly presented in all treated Chiang rice starches. The peak became progressively stronger with increasing moisture level of the treatment. Differential scanning calorimetry (DSC) of all treated rice starches showed a shift of the gelatinization temperature to higher values. Increasing moisture level of the treatments increased the onset gelatinization temperature (T_o) but decreased the gelatinization enthalpy (ΔH) of rice starches. A broad gelatinization temperature range (T_c‐T_o) with a biphasic endotherm was found for all treated Chiang rice starches and Jasmine rice starch after HMT₂₇ (HMT at 27% moisture level). Additionally the (T_c‐T_o) of treated Chiang rice starches increased linearly with increasing moisture level of the treatments.     

Interaction of wheat and rice starches with yellow mustard mucilage

The effect of yellow mustard mucilage (YMM) on gelatinization and retrogradation of wheat and rice starches were studied. Considerable interactions were observed between YMM and wheat and rice starches which were accompanied by a marked increase in viscosity. DSC studies showed that the presence of YMM did not affect peak gelatinization temperature (T_p) of wheat and rice starches, but slightly increased melting enthalpy (ΔH) and the phase transition temperature range (T_c−T₀). Addition of YMM markedly changed wheat and rice starch gel textures by increasing hardness, adhesiveness, chewiness and springiness. The addition of YMM–locust bean gum (LBG) mixture (9:1) similarly increased the viscosity of wheat and rice starches but decreased gel hardness. The swelling power as well as solubilized starch and amylose were decreased for both starches in the presence of YMM. Syneresis in wheat and rice starches was also decreased by the presence of YMM.     

Formation of starch spherulites: Role of amylose content and thermal events

Commercial maize starches and potato starches of two cultivars differing in physicochemical composition (granule size distribution; amylose to amylopectin ratio) and crystallinity were heated to 180 °C and then cooled by fast quench using a differential scanning calorimeter (DSC), in order to produce spherulitic starch morphologies. Among the raw maize starches, waxy maize starch had highest relative crystallinity (49%) whereas a lowest crystallinity of 33–39% was calculated for high-amylose maize starches. Potato starches showed a relative crystallinity of 50%. The temperatures and enthalpies of gelatinisation and melting varied among all the starches. High-amylose maize starches showed higher transition temperatures of gelatinisation (T_gel), whereas waxy maize starch had lowest T_gel and enthalpy of gelatinisation (ΔH_gel). Similarly, a considerable variation in parameters related with crystalline melting (T_m1, T_m2 and ΔH_m1, ΔH_m2) was observed for different starches. The superheated gels of different starches treated using DSC were subjected to polarised microscopy, to confirm the formation of spherulites. Both the high-amylose starch gels showed the presence of spherulites exhibiting birefringence and a weak crystalline pattern. No birefringence was observed for waxy maize starch gel, while potato starch gels had some birefringence. The particle size distribution of high-amylose maize starch gels analysed through Zetasizer showed the sizes of spherulitic particles fall in the range of 300 nm–900 nm. The scanning electron micrographs of the dried high-amylose maize starch gels showed the presence of round spherulites consisting of several aggregated spherulitic particles. Amylose content and melting of crystallites during heating play an important role during recrystallisation of amylose (spherulite morphologies).     

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.     

Influence of Heat‐Moisture Treatment and Acid Modifications on Physicochemical,Rheological, Thermal and Morphological Characteristics of Indian Water Chestnut (Trapa natans) Starch and its Application in Biodegradable Films

Water chestnut starch was subjected to acid modification and heat‐moisture treatment. Hydrochloric acid was used for acid modification at three different concentrations (0.25 M, 0.5 M and 1 M) for 2 h. Modifications did not alter the granule morphology. Heat‐moisture treatment (HMT) resulted in slight reduction in the granular size of the starch granules. Acid modification lowered the amylose content, swelling power, water‐ and oil‐binding capacity but improved the solubility of starch to a considerable level. Light transmittance of acid‐modified (AM) starches improved significantly. A significant reduction in peak, trough, final and setback viscosity was observed by acid‐thinning. In case of heat‐moisture treated starch the final viscosity (F_v) was found to be even higher than the peak viscosity (P_v). Native water chestnut starch exhibited a lower onset temperature (T_o) and peak temperature (T_p) of gelatinization than the corresponding acid‐treated starches. Starch films prepared from native starch exhibited excellent pliability, whereas those prepared from AM and HMT starches showed good tensile strength. Starch films prepared from acid‐treated starches provided better puncture and tensile strength.     

Molecular Background of Technological Properties of Selected Starches

Selected starches, i.e. waxy maize, amaranth, quinoa, wheat, millet and buckwheat starches, were investigated with respect to their technological properties such as gelatinization, stability to mechanical stress, resistance to conditions and stability in continuous freeze/thaw cycles. Technological properties are correlated with molecular features such as branching characteristics in terms of iodine-complexing potential, molar mass, occupied glucan-coil volume, packing density of glucan coils and rheological properties. Waxy maize and amaranth starches were found to be amylopectin-type short-chain branched (scb) glucans with weight average molar masses M_w = 17 × 10⁶ g/mol and 12 × 10⁶ g/mol, respectively. Waxy maize starch had a high gelatinization potential, high viscosity at 95 °C (340 mPas) low stability at acidic conditions, average stability to shearing and good freeze/thaw stability. For amaranth starch a viscosity of 122 mPas at 95 °C, low resistance to acid, but high stability to applied shearing and even high freeze/thaw stability was determined. Investigated quinoa starch was classified as scb-type glucan, however, the branches are significantly longer than those of waxy maize and amaranth. With a M_w = 11 × 10⁶ g/mol and a viscosity of 187 mPas at 95 °C, this sample is comparably resistant to acidic conditions and to shearing, but instable in freeze/thaw experiments. Wheat, millet and buckwheat starches contain significant percentages of amylose-type long-chain branched (lcb) glucans (22.1, 32.1 and 24.3 %, respectively) with M_w values of 5 × 10⁶ g/mol, 12 × 10⁶ g/mol and 15 × 10⁶ g/mol, respectively. Wheat starch, with a viscosity of 107 mPas at 95 °C, shows low stability under acidic conditions, but high stability to shearing. Wheat and millet starches, but not buckwheat starch, form weak gels in the course of subsequent freeze/thaw cycles. Millet starch, with a viscosity of 101 mPas at 95 °C was found to be moderately stable under acidic conditions and to shearing. Buckwheat starch with a viscosity of 230 mPas at 95 °C shows no acid resistance and is instable upon shearing but performs very well in freeze/thaw experiments.     

Some Structural Characteristics of Starches of Maize Having a Specific Genetic Background

Distribution of starch components of maize (Zea mays L.) and their properties were investigated by gel filtration after debranching and by exhaustive hydrolysis of starch-granules with glucoamylase. Based on the results, relationship between genotypes and properties of starch components were discussed. The sugary-1 (su₁), sugary-2 (su₂), and dull (du) mutants produced high amylose maize, while amylopectin of su₂ was normal type and those of su₁ and du were novel type. In the double-mutant combinations, the waxy (wx) gene decreased amylose content. Starches of du su₁ or du su₂ possessed greatest amount of amylose among starches examined. Contents of amylose, intermediate fraction (Fr.) and longer branches of amylopectin increased in most cases when the amylose-extender (ae) gene was introduced. Starches of ae possessed longer average chain-lengths of amylopectin than that of normal. In ae du starches, however, elongation of the amylopectin chain and increase of the intermediate Fr. did not occur. Exhaustive degradation of starch-granules by glucoamylase showed that ae starches were more resistant to amylase.     

Chain Length Distribution of Amylopectins of Several Single Mutants and the Normal Counterpart,and Sugary-1 Phytoglycogen in Maize (Zea mays L.)

β-Limit dextrins of starches of normal (nonmutant), amylose-extender (ae), dull (du), sugary-2 (su₂) and waxy (wx) maize, and phytoglycogen of sugar-1 (su₁) maize were prepared. The β-limit dextrins were successively debranched by isoamylase and pullulanase, and followed by quantitative gel-filtration. The ratio of A to B chains for the ae starch appeared to be high and that for su₁ phytoglycogen was low. The ratio of short B to long B chains for the du starch was high and that for the ae starch appeared to be low. The phytoglycogen did not contain long B chains. The unit chain-length distribution of amylopectins of the normal, wx, and su₂ starches were similar. Fine structures of maize amylopectins and su₁ phytoglycogen were modeled and described.