酸解时间对大米淀粉结构性质的影响

以4种不同直链淀粉含量的大米淀粉(0%的优糯3号、10.90%的稻花灿、21.03%的聚两优、28.46%的华优香占)为原料,酸解处理不同时间,以酸解大米淀粉的酸解率、颗粒形貌、结晶性质、溶解度的变化为指标衡量不同酸解时间对大米淀粉结构及性质的影响。结果表明,不同直链淀粉含量的大米淀粉具有不同的耐酸性,酸解时间对不同直链淀粉含量大米淀粉的结构和性质有着不同的影响。大米淀粉酸解率与直链淀粉含量成反比,优糯3号为50%而华优香占仅为30%;所有淀粉颗粒在酸解后均产生一定程度的破碎,偏光十字变形直至消失,酸解相同时间,直链淀粉含量高的大米淀粉破碎率低;酸解未改变淀粉的晶型,仍为A晶型;随着酸解时间的延长相对结晶度增加;淀粉的溶解度随着酸解时间的增加而增大。     

Effect of acid‐ethanol treatment followed by ball milling on structural and physicochemical characteristics of cassava starch

Structural and physicochemical characteristics of cassava starch treated with 0.36% HCl in anhydrous ethanol during 1 and 12 h at 30, 40, and 50°C followed by ball milling for 1 h were analyzed. Average yield of acid‐ethanol starches reached 98% independent of the treatment conditions. Solubility of acid‐ethanol starches increased with reaction temperature and time, but it did not change after ball milling. Granule average size reduced with chemical treatment from 25.2 to 20.0 µm after 12 h at 50°C. Ball milling decreased the granule average diameter of the native starch and those chemically treated at 30°C/1 h or 40°C/1 h, but it did not alter the starches treated for 12 h, independent of temperature. From scanning electron microscopy (SEM), starch granules presented round shape and after modification at 50°C/12 h, before and after ball milling, showed a rough and exfoliated surface. Some granules were deformed, suggesting partial gelatinization that was more intense after milling. Starch crystallinity increased as temperature and time of chemical treatment were increased, while amylose content, intrinsic, and pasting viscosities decreased. Gelatinization temperatures increased for all chemical starches. The findings can be related to the preferential destruction of amorphous areas in the granules, which are composed of amylose and amylopectin. After ball milling, the starch crystallinity decreased, amylose content, intrinsic, and pasting viscosities kept unchanged and gelatinization temperatures and enthalpy reduced. Ball milling on native and chemical starches caused the increase of amorphous areas with consequent weakening and decreasing of crystalline areas by breaking of hydrogen bonds within the granules.     

Studies on tuber and root starches. I. Structure and physicochemical properties of innala (Solenostemon rotundifolius) starches grown in Sri Lanka

Starches from two cultivars (Bola and Dik) of innala tubers (Solenostemon rotundifolius) grown in the same location and under identical environmental conditions in Sri Lanka was isolated and some of the characteristics determined. The yield of starch from both cultivars was 16.0% on initial tuber weight. The shape of the granules in both cultivars was dome shaped and hemispherical with 4–5 slightly concaved facets. Pores were found randomly distributed over the surface of both starch granules. The amylopectin branch chain length distribution was nearly similar for both starches. However, the starches differed with respect to granular swelling, amylose leaching, susceptibility towards acid and enzyme hydrolysis, gelatinization characteristics, pasting properties and retrogradation kinetics. The results showed that differences in amylose content, lipid complexed amylose chains, relative crystallinity and extent of interaction between amylose chains in the amorphous regions of the granule had a substantial impact on the observed differences in physicochemical properties.     

The impact of heat-moisture treatment on molecular structures and properties of starches isolated from different botanical sources

Heat-moisture treatment is a hydrothermal treatment that changes the physicochemical properties of starches by facilitating starch chain interactions within the amorphous and crystalline domains and/or by disrupting starch crystallites. The extent of these changes is influenced by starch composition, moisture content and temperature during treatment, and by the organization of amylose and amylopectin chains within native starch granules. During heat-moisture treatment starch granules at low moisture levels [(<35% water (w/w)] are heated at a temperature above the glass transition temperature (T(g)) but below the gelatinization temperature for a fixed period of time. Significant progress in heat-moisture treatment has been made during the last 15 years, as reflected by numerous publications on this subject. Therefore, this review summarizes the current knowledge on the impact of heat-moisture treatment on the composition, granule morphology, crystallinity, X-ray pattern, granular swelling, amylose leaching, pasting properties, gelatinization and retrogradation parameters, and susceptibility towards α-amylase and acid hydrolysis. The application of heat-moisture treatment in the food industry is also reviewed. Recommendations for future research are outlined.     

Physicochemical Properties of Ginkgo Kernal Starch

Native starch was isolated from ginkgo kernels, its physicochemical properties were investigated using some physical methods. Ginkgo starch granules were mostly oval in shape with a central Maltese cross and average long axis of 11 μm. Ginkgo starch contained 29.9% amylose content and exhibited an A-type crystallinity with 27.2% crystalline degree. Ginkgo starch had significantly higher gelatinization conclusion temperature, temperature range, and enthalpy than potato and rice starches. Ginkgo starch showed lower hot viscosity and higher breakdown viscosity than potato and rice starches. Ginkgo starch possessed markedly higher swelling power and resistance to α-amylase and amyloglucosidase hydrolysis than rice starch.     

Influence of acid hydrolysis on thermal and rheological properties of amaranth starches varying in amylose content

BACKGROUND: The granules of amaranth starch are very small compared with starches from other sources. In the current work, amaranth starches with different amylose contents were treated with hydrochloric acid as a function of time in order to study the effect of acid treatments on starches. Differential scanning calorimetry and dynamic oscillation in shear were employed to analyse the thermal and rheological properties of acid‐modified amaranth starch. RESULTS: Results showed that gelatinisation temperatures and enthalpy change of gelatinisation (ΔH) decreased steeply initially, and had a slight increase with further treatment up to 12 h then decreased, an outcome that reflected distinct resistance to acid with various amylose contents. Rheological parameters of storage and loss moduli during heating, cooling and frequency sweep of modified starches reflected the differential scanning calorimetry results by decreasing in value as the time of acid hydrolysis increased. CONCLUSION: With amylose content increase, the effects of acid hydrolysis on gelatinisation temperatures became less pronounced. Nevertheless, prolonged acid hydrolysis decreased the storage and loss moduli, with the starch pastes becoming more liquid‐like. Copyright © 2012 Society of Chemical Industry     

Effect of Acid‐Methanol Treatment on the Physicochemical and Structural Characteristics of Cassava and Maize Starches

Physicochemical, structural and morphological characteristics of maize and cassava starches treated with 0.36% concentrated HCl in anhydrous methanol at 54ºC for 1–8 h were analyzed and compared. Average yield of modified starch was about 97% for both starches. The solubility of the acid‐methanol treated starches increased with temperature and after 3 h of treatment reached 93% for maize starch and 97% for cassava starch at 95ºC. After 8 h of treatment, the average size of the cassava starch granules decreased from 14.9 to 11.1 µm. The action of acid‐methanol on the maize starch was more subtle, reducing the granule average size from 11.8 to 11.3 µm. Scanning electron micrographs showed that the granule surfaces were rough and exfoliated after treatment suggesting exocorrosion that was more evident for cassava starch. From GPC, it was noted that amylose and amylopectin were partially degraded during treatment. Starch crystallinity gradually increased with duration of treatment. The amylose content decreased from 21.4 to 18.8% and from 26.3 to 23.0% and the intrinsic viscosity was reduced from 2.36 to 0.21 and from 1.85 to 0.04 for cassava and maize starches, respectively. The gelatinization temperatures increased whereas pasting viscosities decreased with reaction time, especially for cassava starch. These results suggested that the attack of acid‐methanol, which was more effective on cassava starch granules, occurred preferentially in the amorphous areas located in the granule periphery and composed of amylose and amylopectin.     

Properties of Residual Starches of Sugary-2 and Sugary-2 Opaque-2 Maize Following Amylase Hydrolysis

Properties of residual starches of sugary-2 opaque-2 and sugary-2 maize starch granules hydrolyzed with glucoamylases were investigated. A crude and two crystalline glucoamylases were used. The amylopectin fractions of both starches hydrolyzed easier than that of amylose with all enzymes. Residual starches hydrolyzed by the crude glucoamylase accumulated low-molecular weight materials, which was not observed in residual starches attacked by crystalline glucoamylase. It was suggested that in the crude enzyme the contaminating α-amylase caused the accumulation of the minified fraction. It is also suggested that the crystalline region of sugary-2 opaque-2 starch may consist of a mixture of A-type and B-type patterns. Evidence for this was from observation of the changes in X-ray diffraction patterns of residual starch following amylase and acid hydrolysis.     

SDS-Sulfite Increases Enzymatic Hydrolysis of Native Sorghum Starches

The sodium dodecyl sulfate (SDS) starch isolation procedure is often used to remove efficiently the surrounding and surface protein of starch granules in order to obtain a pure starch sample. In this study the changes in enzymatic hydrolysis of sorghum starch granules due to SDS-sulfite solution treatment were investigated. As SDS-sulfite solution soak time increased, enzymatic hydrolysis rate increased and the Michaelis-Menten pattern of enzymatic reaction did not change. The degree of this effect differed among starches from three sorghum cultivars. The effect of SDS-sulfite solution treatment on enzymatic hydrolysis became negligible after the treated starch samples were partially hydrolyzed. The adsorption of α-amylase onto the starch granules also increased with SDS-sulfite solution treatment and was highly correlated with hydrolysis rate. The different effects of SDS-sulfite solution on enzymatic hydrolysis of the three sorghum starches were related to the properties of the amorphous regions in starch granules.     

A Study of Some Physicochemical Properties of High‐Crystalline Tapioca Starch

Tapioca starch was partially hydrolyzed in hydrochloric acid solution at room temperature for various lengths of time to obtain high‐crystalline starches. RVA viscoamylograms of acid‐modified starches demonstrated a very low viscosity as compared to that of native tapioca starch. The relative crystallinity of native and acid‐modified tapioca starches were measured by X‐ray diffraction ranging from 39.53% to 57.75%. The native and acid‐modified tapioca starches were compressed into tablets using various compression forces. The % relative crystallinity of starch increased with the increase in hydrolysis time and the crushing strength of the tablet was also increased in line with the crystallinity while the amylose content decreased when the crystallinity increased. These results suggested that the erosion of amylose might cause the rearrangement of starch structure into a new more tightly packed form, which provided the higher crushing strength for the tablets.     

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.     

In vitro digestibility,pasting, and structural properties of starches from different cereals

Starches isolated from seven different cereals were evaluated for their composition, physicochemical, in vitro digestibility, structural, morphological, and pasting properties. The in vitro starch digestion rate and estimated glycemic index (GI) of cereal starches were evaluated along with the impact of cooking on starch digestion. The cooking of starch slurries increased the rapidly digestible starch content from a range of 34.7–54.4% to a range of 60.5–78.5%. On the basis of hydrolysis index, the GI ranged from 83.6 to 91.8 and after cooking it increased from 95.1 to 98.6 for different cereal starches. Both the swelling power and solubility showed an increasing trend with rising temperature. Paste clarity of starches negatively correlated with fat content. The amylose content of various starches ranged from 17.7 to 24.7% and was negatively correlated to crystalline index (r = -0.975, p ≤ 0.05). XRD pattern revealed A-type pattern of crystalline starch, where crystallinity index ranging between 28.2 to 44.9%. FTIR revealed slight differences among chemical bonding of starches from different cereals. From scanning electron micrograph observations, wheat and barley starch granules proved smoother as compared to other cereal granules. Barley contained the highest (27.5 µm) and rice had the lowest (10.2 µm) size starch granules. The pasting properties were significantly (p ≤ 0.05) different for different cereal starches. Peak, breakdown, and final viscosities were the highest for maize starch (1725, 384, and 2112 mPa.s, respectively), whereas rice and oats exhibited the highest trough and setback viscosities (1420 and 954 mPa.s, respectively).     

Amidons Lintnérisés Etudes chromatographique et enzymatique des résidus insolubles provenant de l'hydrolyse chlorhydrique d'amidons de céréales,en particulier de maïs cireux

Lintnerized Starches. Chromatographic and Enzymatic Studies of Insoluble Residues from Acid Hydrolysis of Various Cereal Starches, Particularly Waxy Maize Starch . Native cereal starches, particularly waxy maize starch, have been carefully hydrolyzed at 35°C with hydrochloric acid (2,2-N) in heterogeneous phase. Observation of the course of hydrolysis as a function of time makes it possible to classify the starches according to their acid lability. The kinetic values distinctly reveal two phases, i.e. a fast hydrolysis of the amorphous fraction and a slower degradation of the crystalline starch grain fraction. This observation was confirmed by X-ray diffractometric patterns. The hydrolysis speed of acid resistant fractions seems to become slower as the apparent amylose ratio increases. The change in the macromolecular structure of the obtained granular residues or “lintnerized” starches as a function of time was examined after aqueous solubilization by means of gel chromatography using a calibrated Sephadex G-50 column. Lintnerization causes a decrease in the apparent DP of the chains of the starch residues and two subgroups with apparent DP 13 and 25 appear rapidly. These DP are unchanging with time of acid treatment. The chromatographic and enzymatic studies of lintnerized starches were performed directly and after successive enzymatic digests with pullulanase and ß-amylase. After debranching of solubilized residues with pullulanase and gel chromatography a linear chain subgroup of DP 15–20 appears. This one is in fact composed of two subgroups: one more important with a DP 13, the other broad distribution with a DP 15–25. The comparison with the subgroups observed before debranching shows that a main part of the initial subgroup of DP 25 could be considered as formed with singly branched chains. Furthermore a small proportion of pullulanase resistant ß-limit dextrins was obtained. The obtained results permits one to suggest a new model for the structure of waxy maize amylopectin. On the basis of this model the differences in structure existing between the various starches are discussed and the results are compared with those reported elsewhere for potato starch. A parallelism between crystalline patterns of native starches and the amylopectin structure, particularly its branching degree, is observed.     

Comparative studies on morphological and crystalline properties of B-type and C-type starches by acid hydrolysis

Comparative studies on acid hydrolysis of B-type Fritillaria starch and C-type Rhizoma Dioscorea and Radix Puerariae starches were carried out using a scanning electron microscope (SEM) and X-ray diffraction (XRD). Fritillaria, Rhizoma Dioscorea and Radix Puerariae starches were hydrolyzed with 2.2 mol/L at 35 °C for 2, 4, 8, 16 and 32 days, respectively. The SEM and XRD results revealed that B-type starch and C-type starch displayed different hydrolysis mechanisms. The acid corrosion started from the exterior surface of B-type starch granules followed by the interior core of starch granules. However, the hydrogen ion primarily attacked the interior of the C-type starch granules and then the exterior of starch granules. B-type starch granule started to crack at the hydrolysis period of 4 days while C-type starch granule was not cracked until the hydrolysis progressed up to 16 days. The crystalline type of B-type starch was not changed with increasing hydrolysis time. However, the crystalline type was gradually changed from C-type to A-type for the Rhizoma Dioscorea and Radix Puerariae starches with increase in the hydrolysis time. This result showed that the B-type polymorphs present in the C-type starch granule was preferentially hydrolyzed during the first stage of hydrolysis.     

Effects of Na2CO3 and NaOH on Pasting Properties of Selected Native Cereal Starches

ABSTRACT: Using a Rapid Visco Analyzer (RVA), it was revealed that 2 alkalizing agents (Na2CO3 and NaOH) had a far larger effect on pasting properties of nonwaxy starches (wheat, corn, rice) compared with their effect on waxy starches (waxy corn and waxy rice). It was hypothesized that the alkalizing agents have a greater propensity to attack the amorphous regions of the nonwaxy starch granules, thereby causing increased leaching of amylose molecules and possibly also some hydrolysis of starch chains. As a result, the RVA pasting profile of a nonwaxy starch, in the presence of alkali, was drastically altered to one that more closely resembled that of its waxy counterpart without added alkali.     

Characterization and Utilization of Acid‐modified Rice Starches for Use in Pharmaceutical Tablet Compression

Acid modified, agglomerated starches offer specific advantages as fillers in production of pharmaceutical tablets. Spray drying can improve processing of tablet mixtures significantly. In order to investigate prerequisites in utilization of rice starch, non‐waxy and waxy types were partially hydrolyzed in 6% (w/v) HCl solution at room temperature for varied length of time to obtain rice starches with increased crystallinity (so‐called crystalline rice starches). Scanning electron micrographs of native and highly crystalline starches were used to study the morphological changes and to suggest the mode of acid attack during hydrolysis. Exo‐corrosion distributed over the surface of acid‐modified waxy rice starch (AWRS) was observed after 192 h of hydrolysis. In contrast, the surface of acid‐modified rice starch (ARS) remained unchanged at 192 h of acid hydrolysis. The amylose content and the median particle size (diameter) were reduced with increasing hydrolysis time. It was found by X‐ray diffraction that the relative crystallinity of acid‐modified starches at >95% relative humidity was clearly increased with prolonged hydrolysis time. For studying tablet properties spherical agglomerates of the native and acid modified starches were directly compressed at 4 kN to obtain tablets. Crushing strength and disintegration time of tablets increased with relative crystallinity. In contrast, tablet friability was reduced. Concerning tablet functionality, the crystalline starches were positioned in overlapping ranges between the common commercial tablet fillers (microcrystalline cellulose, pregelatinized starch and lactose, respectively).     

Enzymatic hydrolysis of granular native and mildly heat-treated tapioca and sweet potato starches at sub-gelatinization temperature

The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were subjected to enzymatic hydrolysis with a mixture of fungal α-amylase and glucoamylase at 35 °C for 24 h. Starches were hydrolyzed in native (granular) state and after heat treatment below gelatinization temperature (60 °C for 30 min). The dextrose equivalent (DE) value of heat-treated starch increased significantly compared to native starch, i.e., 36–50% and 27–34% for tapioca and sweet potato starch, respectively. Scanning electron microscopy examination showed that enzymatic erosion occurred mainly at the surface of starch granules. Hydrolyzed heat-treated starch exhibited rougher surface and porous granules compared to native starch. X-ray analysis suggested that enzymatic erosion preferentially occurred in amorphous areas of the granules. The amylose content, swelling power and solubility showed insignificant increase for both starches. Evidently, heating treatment below gelatinization temperature was effective in enhancing the degree of hydrolysis of granular starch.     

Granule Sizes of Canna (Canna edulis) Starches and their Reactivity Toward Hydration,Enzyme Hydrolysis and Chemical Substitution

Small and large granule fractions were isolated from canna starch (Canna edulis, green leaf cultivar), and their morphology, physicochemical properties, susceptibility towards granular starch hydrolyzing enzymes and chemical reaction with propylene oxide were investigated. Canna starch consisted of a mixed population of large, medium and small granules; the mean of granule diameter was 47.4 μm. The small granules presented round and polygonal shapes, whereas the large granules had oval and elliptical shapes. Significant variations in digestibility of the various granules size by granular starch hydrolyzing enzymes were observed. During the first 24 h, the hydrolysis rate of small granules was higher than that of native and large granule starches. After 72 h, however, the degree of hydrolysis of small granule, large granule and native starches had reached the extent of 19.6%, 32.0% and 27.2%, respectively. The larger the granule size, the higher the MS obtained when modified with propylene oxide, which was due to the higher swelling power of the large granules. The results obtained from this study suggest that small granules had lower water and chemical affinity when compared with the bigger ones. The difference in the reactivity of small and large granules could be presumably attributed to the starch components (amylose and amylopectin) and their organization of glucan chains in ordered and/or less ordered structure of these two fractions.     

体内外消化高直链抗性水稻淀粉的波谱特性

以基因工程培育出来的高直链抗性淀粉水稻(TRS)为材料,利用粉末X射线衍射、傅里叶变换红外光谱分析技术,研究体内外消化TRS淀粉的波谱特性。结果表明：不被消化的抗性淀粉直链淀粉含量显著升高;TRS淀粉为C型晶体淀粉,由A型和B型晶体淀粉组成,其中A型晶体比B型晶体消化降解快,B型晶体具有抗消化降解的作用;TRS淀粉的无定形区域易被消化降解。     

The effect of the structure of native banana starch from two varieties on its acid hydrolysis

Two banana starches were studied to analyze the effect of the acid hydrolysis on their molecular structure, and the impact in their physicochemical features. The native banana starches exhibit differences in the amylose content, molar mass, gelatinization parameters, X-ray diffraction pattern, and pasting profile. These results suggested that different acid hydrolysis mechanisms may be operative in these two starches. The kinetic hydrolysis is different in both banana starches that are related to the crystalline packing of the starch molecules. This was confirmed by the amylose content, the X-ray diffraction pattern, and the thermal study in the acid hydrolyzed starches at different times. The acid-treated Roatan starch showed higher retrogradation than Macho starch, a phenomenon that increases in the sample hydrolyzed for the longer time. This pattern is related to the amylose/amylopectin ratio, the reduction in the molar mass and the gyration radius. The acid hydrolysis of banana starches, although they have some similarities, they are different.