Optical Interference Studies on Single Starch Granules

Studies on the optical interference by potato, sorghum, wheat, pigeon pea and cowpea starch granules indicated that the potato granule was ordered mostly on the centre of the granule and that the molecular arrangement of the birefringent portion was perpendicular to the radial. This was more so with the legume starches where the entire granule was ordered. Cereal starches had birefringent material on the periphery and non-birefringent material in the centre and in this case, the birefringent material was radially arranged.     

Scattering Studies of the Internal Structure of Starch Granules

Small Angle X‐ray Scattering (SAXS) and Small Angle Neutron Scattering (SANS) are applied to the study of the internal supramolecular packing within starch granules. SAXS is able to provide information on the packing of the semicrystalline lamellae and the amorphous growth rings. Using synchrotron radiation it is possible to follow changes in structure at both elevated temperatures within the gelatinisation regime, and at sub‐zero temperatures when ice crystallisation can change the packing via compression of the granule. The role of amylose in modifying the response of the granule to these temperature variations has been examined. SANS has been used to examine the distribution of water in different parts of the granule, and quantify the molecular densities in different regions of the granule.     

Flow Cytometric Determination of Light Scattering and Absorbance Properties of Starch Granules

Treatment of samples of digested endosperm with SDS resulted in a homogenous suspension of single starch granules that was suitable for analysis by flow cytometry without altering their refractive properties. Flow cytometry can be used for more rapid and accurate enumeration of starch granules than can be achieved with a hemocytometer as with the latter the number of starch granules seems to be underestimated. Moreover, flow cytometric analysis based on forward angle light scatter (FALS) and absorbance properties revealed that there are at least three unique subclasses of starch granules that appear during kernel development. The first subclass contained mainly small granules (2–5 μm) whereas the second subclass generally consisted of large granules (> 5 μm). However, within a given size, there were two distinct subpopulations with significantly different absorbance properties. The physiological or physicochemical significants of these subclasses warrant further investigation.     

Studies of the Dynamics of the Gelatinization of Starch Granules Employing a Small Angle Light Scattering System

Although the effects of water and sugars upon starch gelatinization have been studied at a physicochemical level, little work has been performed on the time dependence of the component processes of gelatinization. It has been shown using a temperature jump technique and monitoring changes by small angle light scattering that the rate of loss of birefringence of 23% w/w wheat starch suspensions in water depends on the size of the temperature jump. Two processes, one fast and one slow are present, the fast predominating in temperature jumps of 8°C, while slower changes are evident in jumps of 2–4°C. The behaviour of wheat starches reflects their different pretreatments. The results have been interpreted in terms of there being a mutual interdependence between the energy relationships governing the stability of the crystallites and the conformation of the chains in the amorphous regions. A semi-cooperative view of the gelatinization process is proposed.     

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.     

Holes in Starch Granules: Confocal,SEM and Light Microscopy Studies of Starch Granule Structure

Following an initial observation of putative holes within potato starch granules during observation in a medium with the same refractive index, the internal architecture of starch granules has been investigated using confocal, scanning electron and light microscopy. These complimentary microscopy techniques confirmed the existence of holes at the hilum of potato, rice and wheat starch granules. Observations were made with minimal sample preparation to avoid the generation of artifactual holes. Using image analysis we have quantitatively measured the occurrence and the size distribution of holes and linked their appearance to the drying of the granule.     

Comparison of Size Characterization of Barley Starch Granules Determined by Electron and Optical Microscopy,Low Angle Laser Light Scattering and Gravitational Field-Flow Fractionation

Several methods were used for the characterization of starch granules isolated from barley kernels. A procedure based on a combination of alkaline digestion, toluene treatment and filtration over sieves with pore diameters of 70 and 40 μm was used for isolation and purification of starch granules from kernels. The released starch granules were characterized by various methods: scanning electron microscopy (SEM), image analysis of optical microscopy data (IAOM), low angle laser light scattering (LALLS), and gravitational field-flow fractionation (GFFF). All methods showed the bimodal size distribution of the isolated starch granules, however, they differed in the ratio of large and small starch granules. LALLS and GFFF were also used for determination of the ratio of large and small starch granules (ratio A/B) isolated from two malting barley cultivars Kompakt and Akcent. Both techniques determined the higher ratio A/B for the cultivar Akcent. SEM was also used to examine the extent of digestion. The micrographs indicate that a significant proportion mainly of small granules are still embedded into residues of endosperm and a more extensive digestion must be performed to release all starch granules from barley kernels.     

Changes in Starch Granules Trapped and Heated Using Optical Tweezers

A microscopic method to investigate the swelling process of individual starch granules heated in excess water is proposed. A starch granule focused under a light microscope is adjustably trapped using the optical tweezing of a near-infrared laser beam, which simultaneously heats the granule. Using this method, morphological changes in starch granules during heating were continuously recorded and quantitatively analyzed by image-processing techniques. The changes in granules of domestic wheat starches with differing amylose content were investigated under irradiation by the laser beam at constant optical power. The shapes of swollen granules of waxy wheat starches were observed to be distinctly different from those of non-waxy starches. Numerical indicators, specifically the time constant of swelling for the granule and its swelling magnification, were also obtained. These showed little relation to the pasting profiles of the same starches, obtained with a Rapid Visco Analyser.     

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.     

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.     

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。     

Studies on Rye Starch Properties and Modification. Part I: Composition and Properties of Rye Starch Granules

Rye is considered as a potential raw material for starch industry. Starting from a survey of technical procedures of isolating starches from rye-flour and -grits investigations will be reported, which were performed on pilot plant- and laboratory-isolated rye starches. The present paper deals with its granule appearance and composition. A distribution of granule size between small granules (⩽ 10 μ − 15%) and large granules (⩾ 11 … ⩽ 40 μ − 85%) is typical for the totality of the starches. Differing distributions depend on the conditions of isolation: the entity of starch containing samples resulted from the laboratory procedures under investigation. Large-granule starch preparations were isolated in the pilot plant: the centrifuge-overflow contains the small-granule fraction which is high in impurities. Granule crystallinity amounts to 16%. The crystalline component - like in wheat and triticale starches - consists predominatly of A-polymorph - with up to 9% of the B-type. The isotherms of water exchange are of the cereal type. The contents of minor constituents largely relate to the small granule fraction which assembles the majority of crude protein, pentosans and lipids, which are difficult to remove

1 Large granule samples may be produced in high purity (⩽ 0,2% crude protein)

. Lipid components in all fractions influence the results of linear chain-iodine interactions and they must be removed to proceed from apparent to absolute polysac-charide indices. The absolute amylose contents amount to ∼ 25% for large granule samples and to 20–21% for small granule samples. The average chain-length of iodine binding helical regions was determined with 220–240 AGU.     

Phospholipids in Starch Granules

The determination of phospholipids in the starches of various plants showed a non-uniform distribution. Potato starch contains lecithin, serine and lysoserinecephalin, and the starch of beans contains additional lysolecithin. In pea starches on lecithin occurs, but ethanolamin and lysoethanolaminecephalin in wrinkled peas and smooth green seeds. The phospholipids of rice starch are lysolecithin as well as ethanolamine- and lysoethanolaminecephalin. The leaves of maize contain ethanolamine-and lysoethanolaminecephalin in their starch. The same lipids and additional lecithin and lysolecthin are the components in the starch of the endosperm starch.     

A Comparision of Starch Granules as Seen by Both Scanning Electron and Ordinary Light Microscopy

Starch being a transparent crystal often give images which are difficult to precisely define with the light microscope due to the diffraction and other effects such as internal structure which may appear as a surface phenomena. The scanning electron microscope (SEM); however, gives only surface detail. In a effort to differentiate between surface and internal details, the same starch granules have been studied by both ordinary light and scanning electron microscopy. In each case the granules were held in the same configuration as was seen with the light microscope when they were studied by SEM. In this way a direct comparison could be made between granules viewed by each microscopy technique. From such comparisons it is possible to determine the starch details that are actually due to internal features. The results for canna, potato and corn starches are given.     

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.     

Studies on Rye Starch Properties and Modification. Part II: Swelling and Solubility Behaviour of Rye Starch Granules

Rye starch shows the typical inhibited swelling behaviour of triticeae starches with an onset of swelling at rather low temperature (50–55°C). Swollen rye starch granules exist as individuals even after swelling at 100°C. The total dispersion of rye starch needs temperatures above 120°C with pressure cooking. On heating of the rye starch suspension preferentially amylose is leached. Defatting of rye starch exhibits no influence on swelling power but results in higher solubility and in increased amylose leaching. The drying procedures applied here resulted in stronger assoziation of the polymer molecules in the starch granule leading to higher swelling temperatures and a reduced solubility. Shiftings of the crystalline/ amorphous-ratio of the starch granules as caused by different drying procedures, had no influence on the results of swelling power investigation but the highest swelling enthalpy as well as Brabender viscosity were exhibited by a sample dried at room temperature. It is proved to be possible to change the swelling behaviour of rye starch to “potato starch type” by slight chemical modification like succination.     

Thermal Conductivity of Starch Granules

Data were obtained at 25°C on thermal conductivities of slurries of starch in a carbon tetrachloride-ethyl benzene mixture having a density equal to that of the starch. The thermal conductivity of granular ordinary corn starch was estimated to be 0.125 B.t.u.-foot per hour-foot^2-0 F by calculation and by extrapolation from the slurry data. The thermal conductivities of granular corn starches decreased with increasing amylose content.     

葛根淀粉颗粒性质的研究

本文对葛根淀粉颗粒的性质进行了研究，包括淀粉颗粒的大小、形貌、X—射线衍射图谱、α—淀粉酶的酶水解作用方式等，并与玉米淀粉进行了比较。结果表明：葛根淀粉平均粒度为24．08μm，小于玉米淀粉的38．97μm；葛根淀粉和玉米淀粉颗粒的偏光十字接近颗粒中心，但葛根淀粉颗粒的偏光十字不明显；葛根淀粉的X—射线衍射图谱为C型，玉米淀粉为A型，而两者的结晶度分别为18％和37％；葛根淀粉和玉米淀粉对α—淀粉酶的作用极为敏感，但在酶解方式上，葛根淀粉是在淀粉粒表面形成许多微孔并经脐心进入淀粉粒内部，而玉米淀粉则是被层层水解，在淀粉粒表面形成很少的微孔。     

Studies on Starch Granules Digestion by α-Amylase

Raw corn starch was partially digested with commercial α-amylase for a short period of 7–8 h at 25°C to obtain granular pitting. The patterns of granular digestion was observed by light and scanning electron microscopy (SEM). The main soluble products of starch digestion were glucose, maltose and higher oligosaccharides. In vitro digestion of starch was discontinued on the basis of nature of granular pitting and relative release of glucose in the reaction mixture. The pitted starch was obtained with high yields and found to be warm water soluble.