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.     

Structural and Physicochemical Characteristics of Lintnerized Native and Sour Cassava Starches

The comprehension of the structure of starch granules is important for the understanding of its physicochemical properties. Native and sour cassava starches after being analyzed with respect to their pasting properties and baking expansion capacity, were treated with 2.2 N HCl at 38 °C for a maximum of nine days. The starch granules remaining after lintnerization were analyzed for amylose content and intrinsic viscosity, by X‐ray diffraction, scanning electron microscopy and chromatographic analysis. The results indicated that the acid hydrolysis on all starches occurred in two steps. The first one, with high hydrolysis rate, was characterized by a quick degradation of the amorphous part of the granules whereas the second step, with lower hydrolysis rate, was characterized by a higher resistance of the organized areas of the granules to acid treatment. Most of the amylose chains were found in the amorphous areas of starch granules only a small percentage was involved in the crystalline regions. The microscopic and chromatographic analysis demonstrated that the acid hydrolysis was not able to disrupt the entire granular crystalline structure. Fermented starch showed amylose and/or amylopectin chain fractions resistant to pullulanase, probably due to structural alterations during fermentation.     

Structure‐Functionality Changes in Starch Following Rough Rice Storage

The molecular‐level features of starch in relation to the changes in rice functionality during storage are not yet fully elucidated. This work investigated the effects of rough rice storage conditions on starch fine structures and physicochemical properties. Dried rough rice samples (medium‐grain Bengal and long‐grain Cypress) were stored at 4, 21, and 38°C in temperature‐controlled chambers and then periodically removed and evaluated after 1, 3, 5, 7, and 9 months. Flour (powdered head rice) and starch (extracted from head rice by alkali steeping) samples were evaluated for pasting and thermal properties. High‐performance size‐exclusion chromatography and high‐performance anion exchange chromatography were used to characterize starch molecular size and amylopectin chain‐length distribution, respectively. Significant changes in starch fine structure were observed primarily on the 38°C lots, and to some extent on the 21°C lots. The decreased amylose: amylopectin ratio, shortened amylopectin average chain length, and the shift in chain‐length distribution to shorter branch chains were implicative of molecular‐level starch degradation. The flour and starch samples showed inconsistent trends in pasting and thermal properties, thus suggesting the role of not only starch but also its interaction with non‐starch components in rice aging.     

Physicochemical Characteristics of Starches from Unripe Fruits of Mango and Banana

Mango and banana starches were isolated from unripe fruits and their morphology; thermal and pasting properties; molar mass and chain length distribution were determined. Mango starch granules were spherical or dome‐shaped and split, while banana starch had elongated granules with a lenticular shape. Amylopectin of both fruit starches had a lower molar mass than maize starch amylopectin; however, mango amylopectin had the highest gyration radius. Banana amylopectin showed the lowest percentage of short chains [degree of polymerization (DP) 6–12] and the highest level of long chains (DP ≥ 37); mango amylopectin presented the highest fraction of short chains, but the level of longest chains was intermediate between those of banana and maize amylopectins. Banana starch presented the highest average gelatinization temperature followed by mango starch and maize starch had the lowest value; a similar pattern was found for the gelatinization enthalpy. The two fruit starches had a lower pasting temperature than maize starch, but the former samples showed higher peak and final viscosities than maize starch. Structural differences identified in the fruit starches explain their physicochemical characteristics such as thermal and pasting behavior.     

Comparison of Endosperm Starch Granule Development and Physicochemical Properties of Starches from Waxy and Non-Waxy Wheat

Starch granule development and physicochemical properties of starches in waxy wheat and non-waxy wheat were investigated in this article. Starch granules in waxy wheat endosperm showed an early developmental process. Compared with non-waxy wheat starch granules (round-shaped), waxy wheat starch granules (ellipse-shaped) were larger and contained more B-type granules. According to the granule size, starch granules were divided into two groups in waxy wheat, but were divided into three groups in non-waxy wheat. Compared with non-waxy wheat starch, waxy wheat starch had higher swelling power, gelatinization temperatures (To, Tp, Tc), and relative degree of crystallinity. They showed similar ordered structures on external regions of starch granules. Additionally, waxy wheat starch had a higher proportion of double-helical components and a lower proportion of single-helical components than non-waxy wheat starch. Based on the previous results, it was concluded: (1) waxy wheat and non-waxy wheat not only differed in starch granule development, but also in physicochemical properties of starches; (2) waxy wheat had more potential value for producing traditional products than non-waxy wheat.     

Granular Properties of Different Starch Phosphate Monoesters

Different starch types (corn, rice, and potato starch, corn amylose and corn amylopectin) were phosphorylated by reaction with a mixture of mono and disodium phosphate at different molar ratios (mol phosphate/mol anhydrous glucose) under heat and vacuum. The starch granules of the modified and the native starches were microscopically examined for their sizes and morphology. The correlation between the variation in granular size of the modified starches with the extent of phosphorylation and some other physicochemical properties was studied. The granular size was generally increased while the iodine absorption capacity was decreased by phosphorylation. There were strong correlations between the variation in the starch granular size in dependence on phosphorylation and the corresponding changes in some physicochemical parameter of starch, e.g. solubility, swelling and paste clarity. This relationship was most evident in the case of phosphorylated corn amylopectin. Starch granular size can be taken as a quick indicator of the physicochemical properties of the native and modified starches.     

不同酰基改性淀粉结构及热稳定性研究

本文用不同链长酸酐对G50玉米淀粉进行化学改性获得酯化淀粉。利用扫描电子显微镜、傅里叶红外光谱、X-射线衍射仪、小角X-射线散射仪及热失重分析仪表征酯化淀粉的表面形貌、分子结构、结晶结构、有序微区结构以及热性能。结果表明,酸酐碳链越长,取代反应程度越低;酯化淀粉颗粒呈碎片状,丁酸酯淀粉(DS=1.38)和己酸酯淀粉(DS=1.37)易聚集成团;酯化淀粉整体呈现无定型态,高取代度乙酸酯淀粉内部有序微区破坏程度最大,取代度相近时,酸酐碳链越长,对应的酯化淀粉存在周期性长程有序结构;相比于原淀粉,酯化淀粉的热稳定性得到增强,且当酸酐添加量相同时,随着酸酐碳链的增加,酯化淀粉的热稳定性增强程度呈下降趋势。以上结果可为完善酯化淀粉应用提供参考。     

脂肪酸链长对高直链玉米淀粉—脂质复合物结构及理化性质的影响

目的：探究淀粉—脂质复合物的形成机理。方法：采用12~18个碳链的脂肪酸与脱支/非脱支高直链玉米淀粉复合,利用差示扫描量热仪、X-射线衍射仪、傅里叶红外光谱仪等分析复合物的热特性、结晶结构及有序结构等,探究脂肪酸链长及脱支/非脱支高直链玉米淀粉对淀粉—脂肪酸复合物结构及性质的影响。结果：脱支处理的淀粉与脂肪酸的复合率随碳链的增长而降低,其中月桂酸复合率最高(15.00%);未脱支处理的淀粉与脂肪酸的复合率随碳链的增长先升高后下降,其中软脂酸复合率(13.73%)最高。复合物的热特性、结晶结构、分子有序度等与其复合程度有关,淀粉和脂肪酸复合后,糊化峰值温度升高,热稳定性升高,经复合后,淀粉由B型结晶结构转变为V型。结论：脂肪酸链长及淀粉脱支对淀粉—脂质复合物结构及理化性质具有较大影响。     

Gel texture and chain structure of amylomaltase-modified starches compared to gelatin

Amylomaltase (AM) (4-α-d-glucanotransferase; E.C. 2.4.1.25) from Thermus thermophilus was used to modify starches from various botanical sources including potato, high amylose potato (HAP), maize, waxy maize, wheat and pea, as well as a chemical oxidized potato starch (Gelamyl 120). Amylopectin chain length distribution, textural properties of gels and molecular weight of 51 enzyme and 7 non-enzyme-modified starches (parent samples) were analyzed. Textural data were compared with the textural properties of gelatin gels. Modifying starch with AM caused broadening of the amylopectin chain length distribution, creating a unimodal distribution. The increase in longer chains was supposedly a combined effect of amylose to amylopectin chain transfer and transfer of cluster units within the amylopectin molecules.Exploratory principal component analysis (PCA) data analysis revealed that the data were composed of two components explaining 94.2% of the total variation. Parent starches formed a cluster separated from that of the AM-modified starches.Extended AM treatments reduced the apparent molecular weight and the gel texture without changing the amylopectin chain length distribution. However, the gel texture was typically increased as compared to the parent starch. AM-modified HAP gels were about twice as hard as gelatin gels at identical concentration, whereas gels of pea starch were comparable to gelatin gels. Modifying Gelamyl 120 and waxy maize with AM did not change the textural properties. Branching enzyme (BE) (1,4-α-d-glucan branching enzyme; EC 2.4.1.18) from Rhodothermus obamensis was used in just one modification and in combination with AM. The combined AM/BE modification of pea starch resulted in starches with shorter amylopectin chains and pastes unable to form gel network even at concentration as high as 12.0% (w/w). The PCA model of all gel texture data gave suggestive evidence for starch structural features being important for generating a gelatin-like texture.     

Effect of twin-xuscrew extrusion combined with cold plasma on multi-scale structure,physicochemical properties,and digestibility of potato starches

The influence of twin-screw extrusion (TSE), cold plasma (CP, 1, 5, and 9 min), and their combination (TSE-CP) treatment on the structural, physicochemical, rheological, solubility, and in vitro digestive properties of potato starches were studied. The results showed that CP slightly changed the starch granules morphology, maintained the growth ring and crystalline structure, promoted depolymerization of the amylopectin branch chain, and increased crystallinity and the ΔH value. It is worth noting that the resistant starch content increased from 84.80 to 86.46% in the short time CP modified potato starch. Meanwhile, TSE and TSE-CP treatments influenced surface morphology, growth ring of potato starch significantly. However, the dually modified potato starch using combined TSE and CP treatments promoted depolymerization of longer chains, increased the proportion of shorter chains and solubility, and improved the degree of hydrolysis. Furthermore, the single and dual treatments did not change the FT-IR spectra pattern. This study suggests that the combination between TSE and CP had more profound modification than the single treatment. The TSE combined with CP is an eco-friendly, thermal, and non-thermal combination technology, which can improve the multi-scale structure of starch and enhance physicochemical properties. Also, the dual treatment can be used to produce modified starch for industrial applications.     

Comparison of Starch Physicochemical Properties from Medium‐Grain Rice Cultivars Grown in California and Arkansas

The starch molecular structure and physicochemical properties of two medium‐grain rice cultivars from Arkansas (Bengal, Medark) and from California (M202, M204) were determined and compared when they were grown in their respective locations and grown together in Arkansas to better understand the impacts of genetics and environment on starch characteristics. Both M202 and M204 contained significantly higher amylose contents (13.2‐15.3%) compared with the Arkansas cultivars (11.6‐12.4%). Starch from the Arkansas rice cultivars exhibited higher pasting and gelatinization temperatures and higher enthalpy values. Rice amylopectin from the California cultivars consisted of a smaller proportion of intermediate chains (DP 13‐24), and had a lower molecular weight and a smaller radius of gyration. When the four cultivars were grown together in Arkansas, the ranges for amylose content narrowed (10.6‐12.4%), their differences in thermal and pasting properties became smaller, and the molecular characteristics of amylose and amylopectin changed for all four cultivars. This study demonstrated that genetics, location, and crop year all contributed to variations in rice starch fine structure and physicochemical properties.     

Influence of molecular structural characteristics on pasting and thermal properties of acid-methanol-treated rice starches

Rice starches from TKW1, TNG67 and TCS17 varieties, differing widely in amylose contents (0.1, 18.3 and 29.2%) were treated at 45 °C for 1 h in methanol containing various amounts of HCl. The recovery, pasting properties, thermal behaviors, molecular size and chain length distribution of starch were observed. Starches exhibited widely different pasting and thermal behavior upon acid-methanol treated (AMT). Degradation of starches upon AMT affected the leaching extent and chain length of amylose. No obvious changes were found on chain length and content of chain fractions of amylopectin. The pasting viscosity of rice starch decreased with increasing concentration of HCl, and the pasting profiles depended on the variety of rice. The pasting profile of AMT-TNG67 starch showed a two-step increasing pattern during heating, while TKW1 and TCS17 starches showed smoothly increasing pasting curves. The relationship between pasting patterns of AMT-TNG67 starches with amylose leaching and two stages of swelling behavior of starch granules was investigated. Results indicated that the pasting of starch granules depend on the amount, as well as the chain length, of amylose in granules.     

Physicochemical Properties of Pin Oak (Quercus palustris Muenchh.) Acorn Starch

Physicochemical properties of acorn (Quercus palustris) starch were studied. Acorn starch granules were spherical or ovoid, with diameters ranging from 3–17 μm. Acorn starch exhibited A‐type X‐ray diffraction pattern, an apparent amylose content of 43.4% and absolute amylose content of 31.4%. Relative to other A‐type starches, acorn amylopectin had a comparable weight‐average molar mass (3.9×10⁸ g/mol), gyration radius (288 nm) and density (16.3 g mol⁻¹nm⁻³). Average amylopectin branch chain‐length corresponded to DP 25.5. Onset gelatinization temperature was 65.0°C and peak gelatinization temperature was considerably higher (73.7°C). The enthalpy change of gelatinization was very high compared to non‐mutant starches (20.8 J/g). An amylose‐lipid thermal transition was not observed. Starch retrograded for 7 d at 4°C had very high peak melting temperature (54.2°C) relative to other A‐type starches. Final (260 RVU) and setback (138 RVU) viscosity of an 8% acorn starch paste was high relative to other starches and pasting temperature was 71.5°C.     

Buckwheat starch: Structures,properties, and applications

BackgroundThere is increasing interest in utilization of buckwheat for healthy food applications. Common buckwheat (Fagopyrum esculentum) and tartary buckwheat (Fagopyrum tataricum) are cultivated in Asia, Europe, and Americas for various food formulation and production. Starch, the major component of the seeds, may account over 70% of the dry weight. Therefore, it is expected that, to a large extent, the quality of starch determines the quality of buckwheat food products. Furthermore, Buckwheat starch has great potential for various food and non-food uses due to the unique structural and functional features.Scope and approachThis review summarises the current knowledge of chemical composition, chemical structure of amylose and amylopectin, physical structure of granules, physicochemical properties, enzyme susceptibility, modifications, and uses of buckwheat starch. Suggestions on how to better understand and utilise the starch are provided.Key findings and conclusionsAmylose contents of buckwheat starch ranged from 20 to 28%. Starch granules are most polygonal with size ranging from ∼2 to 15 μm and an average diameter of ∼6–7 μm. The polymorph is A-type. The amount of extra-long unit chains of amylopectin (DP > 100) is higher than that of cereal amylopectins. Low glycaemic index of buckwheat food products could be attributed to the non-starch components. Buckwheat starch has been used as fat replacer, ingredient for extruded products, nanocomposite material, and fermentation substrate for alcoholic beverage. It may be concluded that buckwheat starch can be a unique source of specialty starch for innovative food and non-food applications.     

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.     

Insights into the relations between the molecular structures and physicochemical properties of normal and waxy wheat B-starch after repeated and continuous annealing

The effect of repeated annealing treatment (RANN) and continuous annealing treatment (CANN) on the structure, physicochemical properties and digestibility of wheat B-starch were studied. Annealing degraded the starch molecules, disrupted amylopectin and amylose structures, and decreased the molecular weight and the long chain of amylopectin. Meanwhile, the double helix structure and the crystalline and amorphous region were broken, the starch and water molecules were rearranged after RANN and CANN. As a result, annealing increased the crystallinity, gelatinisation temperature, resistant starch and slowly digestible starch content, while decreased the solubility, swelling power and pasting viscosity. The different changes of structural and physicochemical properties for normal and waxy B-starch upon annealing treatment were because of the different amylose contents and amylopectin chain mobility. The RANN exhibited greater advantages than CANN in the modification of the structural, physicochemical, and digestible properties of normal B-starch; while CANN significantly affected properties of waxy B-starch.     

黑糯米和血糯米淀粉结构及物化性质的对比分析

本研究从黑糯米、血糯米中提取淀粉,对其表观结构、球晶结构、支链链长、结晶结构、短程结构、黏度性质、糊化性质、老化性质进行对比分析。结果表明：两种淀粉颗粒形态类似,均具有双折射现象;黑糯米淀粉支链中A链、B2链所占比例较低,B1链、B3链所占比例较高;X衍射结果表明,两种淀粉均属于A型晶体,血糯米淀粉相对结晶度较高;红外结果表明,血糯米淀粉有序程度较高,无序程度较低;黏度结果表明,血糯米淀粉峰值黏度、崩解值较高,回升值、糊化温度较低;热力学结果表明,黑糯米淀粉起始温度、峰值温度、终止温度均较高,且更容易发生老化。两种淀粉在结构特性、物化性质方面存在差异,为指导糯米原材料的选用及其在食品工业中的合理开发利用和深加工提供理论依据。     

Morphological,Physicochemical and Structural Characteristics of Oxidized Barley and Corn Starches

Barley starch was oxidized to different levels and the morphological, physicochemical and structural of the resultant oxidized barley starch were determined and compared with oxidized corn starch at the same oxidation level. The amylose content in oxidized starches decreased with increasing oxidation level, and the extent of decrease was similar for both starch types. No evidences of alteration in morphology and X‐ray diffraction pattern were noted after oxidation. The crystallinity of barley starch increased with increasing oxidation but corn starch displayed a reduced crystallinity at 5% NaOCl. The onset and peak gelatinization temperatures of oxidized starches as measured by differential scanning calorimetry showed a slight increase up to 3% NaOCl and then decreased at 5% NaOCl, whereas gelatinization enthalpy gradually decreased with increasing oxidation level. The melting temperature of retrograded oxidized starches increased with increasing oxidation. Both amylose and amylopectin were degraded during oxidation, but a higher degradation in both components as determined by high‐performance size‐exclusion chromatography (HPSEC) was noted for barley starch than for corn starch. Results of amylopectin chain‐length distribution showed that the proportions of A and B1 chains significantly increased while that of B2+ chains significantly decreased. These results suggest that differences in the structure of barley and corn starches affected their responses to oxidation. Barley starch seemed to be more susceptible to oxidation with more significant reduction in pasting temperature, viscosity, and molecular size than corn starch.     

流化床气流超微粉碎对马铃薯淀粉结构及性质的影响

为研究流化床气流超微粉碎对淀粉结构及性质的影响,以马铃薯淀粉为原料,采用激光粒度分析仪、扫描电子显微镜、光电子能谱仪、同步热分析仪、流变仪等多种仪器及分析手段,考察气流粉碎对马铃薯淀粉颗粒大小及形貌、表面基团、热稳定性、流变特性、溶解度、膨胀度及透明度等结构及性质的影响。结果表明:马铃薯原淀粉经气流粉碎微细化处理后,平均粒径（D₅₀）减小至13.59±0.04 μm;X射线光电子能谱（XPS）的谱图中没有出现新元素峰位,淀粉颗粒表面没有引入新元素;直链淀粉含量增加,支链淀粉分子链变短,溶解度、膨胀度和淀粉糊透明度增加;粘性阻力减小,表观粘度降低;淀粉分子氢键及分子链均发生断裂,凝沉性下降,该研究为马铃薯淀粉的深度加工与应用提供了理论依据及技术支撑。     

The Effects of Environmental Conditions on the Structural Features and Physico‐chemical Properties of Starches

The effects of environmental factors on the structural features and physico‐chemical properties of starch (from various botanical sources) have been investigated over many decades. A close study of published data on the effects of environmental factors, especially growth temperature, reveals discrepancies with regard to its effects on the composition and properties of the major components of starch, namely amylose and amylopectin. These discrepancies can in part be explained on the basis of the different experimental protocols used by the various investigators to provide environmental variation although it is clear that environmental factors do influence the deposition and composition of starch granules. However, the effects of environmental conditions on the physical properties of starches are more easily reproduced and are consequently better understood. This review is an up to date survey of current knowledge in this area and draws extensively on the authors' own research.