Studies on the Biosynthesis of Starch Granules. Part 6. Properties of the Starch Granules of Normal Barley,and Barley with Starch of High Amylose-Content,During Growth

The granular morphology of two types of barley starch, widely different in amylose-content, has been investigated during the period of starch accumulation. The pattern by which the granules were laid down was markedly different, despite the previously observed similarities in the changes in the ratio and nature of the starch components.     

Effect of Metal Cations on the Swelling and Gelatinization Behaviour of Large Wheat Starch Granules

The effect of metal cations on the swelling and gelatinization behaviour of large wheat starch granules has been studied by observing their behaviour in the presence of 24 different chlorides in aqueous solutions. With most salts, increasing concentration results in gelatinization temperatures being first raised, then depressed, and then raised again. Increasing salt concentration may also cause the initial loss of anisotropy to occur at the granule surface instead of at the hilum, and result in an apparent solution of starch rather than swollen granules. The gelatinization phenomena have been classified into three major types, and these are described in detail. It is suggested that both water and partially hydrated salts can act as gelling agents for starch granules, and that the interplay of these two agencies can explain the observed complex relation between gelatinization temperature and salt concentration.     

Stereological Analysis of the Contribution Made to Mature Wheat Endosperm Starch by Large and Small Granules

The contribution made to the total starch content of wheat endosperm by small B type granules has, in the past, generally been under-estimated. Using stereological point-counting methods on endosperm tissue sections we present a revised figure which is in agreement with data from sieving analyses.     

A Reassessment of the Chemical Structure of Barley and Wheat Starch Granules

Barley starch exists in two clearly defined populations of large (ca. 25 μ diameter) and small (ca. 5, μ diameter) granules, whilst in wheat there is a range of granule sizes with no similar bimodal distribution. The small granules of barley represent about 90% of the total starch granules by number, but account for only about 10% of the total starch in weight. Fractions containing only large or only small granules have been isolated from both barley and wheat. The small granules from barley have a higher amylose content than the large granules, a higher gelatinisation temperature, and are usually associated with more protein. In contrast, large and small granules from wheat differ only slightly in their respective amylose contents but, like barley differ in gelatinisation temperatures and amounts of associated protein. It is proposed that starch synthesis in the small starch granules of barley is under different genetic control from that in the large granules.     

Differential Binding of Concanavilin A to Starch Granules Isolated from Barley and Maize

The location of amylose and amylopectin components and/or the degree of branching at the exterior of starch granules may influence the binding of F. I. T. C. labelled Concanavilin A. Waxy Maize starch granules and small starch granules from barley have a higher affinity for lectin than starch granules isolated from normal maize or large starch granules isolated from barley kernels. The binding of Concanavilin A to starch granules is shown to be cooperative and reversible.     

Studies on Starch Granules

In X-ray diffractometric studies on starch granules of many kinds of plant species, we found a variety of intermediate C-type patterns. In particular, specimens of sweet potato starch granules varied from nearly the A-type pattern to nearly the B-type pattern. In these studies, we also found that spheroids of short chain amylodextrin showed very sharp diffraction patterns and that we could form amylodextrin spheroids with various types of X-ray diffraction patterns by varying the conditions of recrystallization. Then we showed that the X-ray patterns and physical properties of many kinds of cereal and root starches varied to some extent depending on the environmental conditions prevailing during the growth period. We examined the formation and the growth of starch granules in corn endosperm and the inner structures of these granules from the beginning to the end of their maturation by electron microscopic observations. We proved also, the appositive growth of starch granules using radio-active carbon dioxide. Then we tried to form starch granules in vitro. But the spheroids obtained from solutions of starch components were entirely different from natural starch granules. From the findings in these experiments, an ultramacromolecular concept of the starch granule is proposed.     

Studies on the Biosynthesis of Starch Granules. Part 8. A Comparison of the Properties of the Small and the Large Granules in Mature Cereal Starches

Starch from four samples of barley and three of wheat has been isolated by two techniques. The total starches were divided into subgroups differing in average granular size, and the relative weights and the amylose-contents of these sub-groups were determined. In the normal cultivars, the amylose-content of the starch was shown to be independent of granule size.     

Barley Starch Granules Subject to SPLITT Cell Fractionation and Sd/StFFF Size Characterization

The coupling of two separation techniques is proposed as a methodology able to fractionate, starch granules of different botanical origins, both on preparative and analytical scale. The split flow thin cell (SPLITT cell) was optimized to produce a binary separation of the starch granules into two different size classes with a 5 μm cutoff point. The size separation was always better than 80%. The Sedimentation Steric Field Flow Fractionation (Sd/StFFF) provides sample particle size distribution (PSD) and is used here to control the SPLITT fractions. The proposed techniques, especially the former, are gentle and easy to use. Both the SPLITT and Sedimentation Fractionation results were checked by scanning electron microscopy (SEM). The procedure was originally applied to two samples from barley. The bimodal diameters were computed.     

Production and Measurement of Starch Damage in Flour. Effect of Starch Damage on Hot Pasting Properties

Aqueous suspensions were made of wheat starches damaged, by different methods, to varying degrees. Apparent viscosities of the hot pastes declined as damage levels increased and the relationships between these factors were examined. Measured as “extractability”, starch damage had a linear relationship with apparent viscosity for starches damaged by both methods. Starch damage measured as “digestibility” had different relationships with apparent viscosity for each type of damage involved. Evidence was found for the association of amylolytic enzymes with the starches used in the experiments.     

Physical Characterization of Amylose-Fatty Acid Complexes in Starch Granules and in Solution

Previous differential scanning calorimetry studies of native starch have shown an endotherm at ∼ 100°C on heating, which is attributed to melting of an amylose-lipid complex. In the present work we have shown that this transition is fully reversible (ΔH ≈ 0.4 ± 0.1 cal g⁻¹ on heating and cooling) and displays substantial thermal hysteresis (T_m≈76°C on cooling). On removal of lipid by extraction with methanol the transition is lost, but re-appears on addition of sodium palmitate to de-fatted granules. Closely similar thermal behaviour, including hysteresis, is observed on addition of palmitate to amylose. Further evidence of complex formation between amylose and palmitate is the almost total disappearance of high resolution ¹H n.m.r. signal, indicating loss of conformational mobility by the polysaccharide chain. Formation of the complex is also accompanied by a large reduction in optical activity. Using an established correlation between D -line optical rotation and the dihedral angles between adjacent residues we have compared the observed optical rotation with values calculated for specific ordered structures of amylose. The measured optical rotation values indicate adoption in solution of a novel right-handed V-amylose structure (calculated [α] D =104°; found = 100±5°) rather than the expected left-handed form characterized in the solid state (calculated [α] D =157°). Analysis of optical rotatory dispersion curves shows that in each case the changes in optical rotation on complex formation arise predominantly from changes in the intensity of the known polysaccharide backbone transition at 161 nm.     

Studies on the Biosynthesis of Starch Granules. Part 9. The Starch Granules from Wrinkled-Seeded Peas

The nature of the complex granules of wrinkled-seeded pea starch has been examined, and related to changes in the starch during growth. An earlier hypothesis for the development of pea starch is shown to be untenable in the light of this information, and possible alternative mechanisms for the biogenesis of pea starch are discussed.     

Studies on the Biosynthesis of Starch Granules. Part 5. Properties of the Starch Components of Normal Barley,and Barley with Sturch of High Amylose-Content,During Growth

Changes in the molecular components of barley starch, from related genotypes of barley differing in amylose-content, have been investigated over the period of reserve-starch deposition in the plants. Striking similarities in the changes in amylose-contents, and in the fine structure of component amylose and amylopectin fractions, were observed over this period, despite the large differences in the types of starch.     

人工老化处理对大麦种子萌发早期淀粉分解的影响

采用高温高湿人工老化处理的方法,探究老化处理对大麦种子淀粉粒及萌发早期淀粉含量和淀粉酶活性的影响。结果表明：人工老化处理未改变大麦种子胚乳淀粉粒的基本形态特征,但使萌发72 h的种子胚乳中小淀粉粒逐渐增加,大淀粉粒逐渐减少,且大淀粉粒表面赤道凹槽和小孔明显减少;随着老化时间的延长,大麦种子内支链淀粉和直链淀粉的含量均呈增加的趋势,α-淀粉酶、β-淀粉酶和极限糊精酶活性均呈降低的趋势,且老化15d与对照相比,淀粉含量和淀粉酶活性差异均达到显著水平。结论：老化使淀粉酶活性降低,淀粉分解减缓,从而导致大麦种子萌发早期淀粉的动员受到抑制。     

The Effect of Barley β-Glucan Fiber Fractions on Starch Gelatinization and Pasting Characteristics

ABSTRACT: We evaluated the effects of extraction treatment on the yield and composition of β-glucan-rich fiber fractions from barley, and the subsequent influence of these fractions on the thermal properties and pasting behavior of starch pastes. Extraction treatment affected the yield of barley β-glucan (BBG) fiber fraction, and β-glucan recovery efficiency ( P < 0.05). The level of inclusion of these fractions in starch-water dispersions had a significant influence on the pasting characteristics such as peak viscosity (PV), breakdown (BD), and final viscosity (FV) development (as determined using a Rapid Visco Analyser). Substitution of 5% wheat starch with the fiber fractions decreased PV, BD, and FV in comparison to the control starch ( P < 0.05). Substitution of 5% wheat starch with BBG fiber fraction resulted in a decrease in enthalpy (J/g) values compared with the control ( P < 0.05). A reduction in pasting characteristics may be associated with a reduced enthalpy of starch gelatinization and retention of the integrity of the starch granule. The reduction in PV may also indicate a reduced degree of starch granule swelling.     

The Effect of Pin and Attrition Milling on Starch Damage in Hard Wheat Flours

Starch damage of 10.9 and 15.7%, respectively, in break and reduction flours of commercial hard wheats was increased to 16.0 and 28.6%, respectively, by pin milling. Attrition milling and cryofreezing prior to pin milling resulted in less pronounced starch damage, apparently due to reduced heat evolution and mechanical stresses as evidenced by the intensities of the X-ray diffraction patterns. Pin-milled flours exhibited chipping and splitting of starch granules as compared to surface abrasions and deep pitting on the granules from attrition-milled flours. It appeared that the latter flours would be more suitable for air classification of hard wheat flours into protein concentrates and starch fractions.     

玉米、木薯及马铃薯淀粉颗粒微晶结构及性质的研究

运用广角X射线衍射分析方法对玉米、木薯及马铃薯淀粉颗粒结晶结构及常温下水的溶胀作用对淀粉颗粒不同微晶结构的影响进行了系统研究,提出了在淀粉颗粒中存在着大量的介于微晶和非晶之间的亚微晶结构,并提供了在一条X射线衍射曲线图中确定微晶、亚微晶和非晶区域的方法。     

The Effect of Extraction Method Upon the Gelatinization Behaviour of Wheat Starch Granules

The effect of extraction method on the characteristics of wheat starch has been examined by differential scanning calorimetry, small angle light scattering and X-ray diffraction. The Banks and Greenwood grain-steeping method in comparison with the Wolf dough washing method has been found to yield a starch with a lower enthalpy of gelatinization, a wider gelatinization range, a higher gelatinization temperature, a lower summed response time index but no difference in the relative X-ray crystallinity. Differential extraction of minor lipid components may be responsible.     

淀粉颗粒形貌与结构的研究

利用光学显微镜对玉米、木薯、马铃薯淀粉颗粒形及结构特征进行了详细的研究和讨论，揭示了不同淀粉颗粒形貌及结构特征之间的共同点和差别，提出了木薯和马铃薯淀粉颗粒首端和尾端的概念以及玉米和木薯淀粉颗粒也存在轮纹和脐点的观点。     

Effect of Shear Energy on Size Reduction of Starch Granules in Extrusion

The changes of size and size distribution of starch granules under extrusion conditions have been investigated by using a single screw extruder and an optical microscope coupled with an image analysis system. The mechanical energy input and material processing time were key factors influencing the degree of starch granular size reduction. In a high shear extrusion process (T=40°C), the weight average granular size of extrudate was reduced from ˜12.4μ (raw waxy corn starch) to 1˜2μ, whereas in a low shear extrusion (T=90°C), and granular size was reduced to ˜7μ. Fine particles (±0.5μ) were observed in both extrusion processes. They were 76% (w/w) under a high shear and long processing time conditions and 5% in a low shear and short time process. During the size reduction process, the peaks of size distribution of starch granules shifted from the large size region toward the medium size region and finally to a rather narrowed peak at the small size region when extensive size reduction measures were applied. Extrusion processes can be used to reduce starch granular size effectively.     

Studies on the Biosynthesis of Starch Granules. Part 7. Compound Granules in Potato Starch

The nature of compound starch granules in potato starch is examined. The relevance of this investigation to the possible formation of potato starch is discussed, and a mechanism for synthesis of compound granules proposed.