Studies of Starch Size and Distribution in 33 Barley Varieties with a Celloscope

Detailed starch particle distribution curves for 33 Finnish barley varieties were determined by a Celloscope technique. All of the curves showed two maxima with respect to both the number and mass. Reproducibility of the counting method was controlled by making duplicate samples to test critical points in the sample treatment. Amounts of the small granules in the barley varieties were rather similar, but average volumes of the large particles varied by even more than 100%. This showed that the essential differences between the varieties appeared in the region termed here as the medium size granules. Based on the knowledge of the accurate size distribution curves from 33 different barley varieties an easy and simple procedure was developed to evaluate granule size distributions of starch in barley samples well enough for practical purposes.     

Monitoring of barley starch amylolysis by gravitational field flow fractionation and MALDI-TOF MS

BACKGROUND: In barley, starch occurs in the form of granules with bimodal size distribution. Enzymatic hydrolysis of the starch granule is one of the most important reactions occurring during malting and mashing. Previous studies revealed the discrepancies in the assumption that barley varieties with better malting qualities should have a higher A/B (large/small starch granules) ratio. This led us to focus our attention on detailed analysis of two barley varieties, Jersey and Tolar, both with high malting quality but significantly differing in A/B (1.28 and 0.66, respectively), were chosen for more detailed analysis in the actual work. In this study, the capacity of gravitational field flow fractionation (GFFF) to monitor amylolysis of the starch granules was investigated. RESULTS: Isolated starch granules from these two barley cultivars were treated with amylases. The changes in starch granule size and bimodal distribution were studied by GFFF. Simultaneously, free sugars released during enzymatic digestion were observed by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry. The changes in the fractogram and in the mass spectra reflect a correlation with the progress of enzymatic hydrolysis. CONCLUSION: The results show the interest in utilization of GFFF as a simple and cheap method for monitoring changes in the distribution of the starch granule size during amylolysis. Copyright © 2011 Society of Chemical Industry     

THE IN VIVO AND IN VITRO DEGRADATION OF BARLEY AND MALT STARCH GRANULES

The susceptibilities to amylolytic hydrolysis of the two different types of starch granule in barley and malt have been investigated. The large and small granules from both germinated and ungerminated grain were subjected to the sole action of malt α-amylase under conditions which otherwise simulated those of a conventional infusion mash. Large starch granules from barley are hydrolysed at a slower rate than those from malt. The faster conversion of the latter is attributed to prior modification of the starch granule structure during germination. The small granules from barley are extremely resistant to attack by α-amylase and even pre-cooking does not appreciably increase their susceptibility to amylase attack. Although the small starch granules from malt are less susceptible than the corresponding large granule fraction, they can be hydrolysed to a greater extent than can the small granules from barley. The increased susceptibility of small granules from malt is probably due to the partial removal of their protecting surface layer of protein. Although during malting the small granules of barley are hydrolysed more rapidly than the large granules, the situation is reversed during mashing. Very little loss of extract can be attributed to the enzymic resistance of small starch granules in all-malt mashes. If raw barley is used in the grist, substantial amounts of small starch granules may remain in the mash.     

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.     

Some Anomalies in Starch Chemistry Are They Due to Granule Structure ?

The small granule starch from cow cockle, pigweed, catch fly and several varieties of dasheens was examined. Although the data suggested that absence of pasting peak, the cooking stability and lack of set-back may be associated with granule size it must due to granule structure since these characteristics were not observed with small granule barley starches. An examination of the “chunk” starch from pigweed indicates that the small granules are cemented together with non-granular starch.     

Comparison of the GFFF and LALLS Methods for the Measurement of Starch Granule Size Distribution in Spring Barley Caryopses

A newly developed method GFFF (Gravitational Field‐Flow Fractionation) and the well known method LALLS (Low Angle Laser Light Scattering) were used to assess starch granule size distribution of ten varieties of spring barley. As a distribution criterion, the ratio of starch granule content larger than 8 μm (type A) and smaller than 8 μm (type B) was chosen. Both methods divided the observed set in a similar way. Varieties Akcent, Forum and Atribut formed a variety set with the highest ratio of large and small starch granules. Varieties Scarlet and Kompakt had intermediate ratios. The remaining five varieties Amulet, Novum, Olbram, Tolar and Krona had the lowest ratios of large and small starch granules. Statistical analysis showed that there was a highly significant correlation between the GFFF and LALLS methods.     

Changes in Starch Granule Size Distribution and Starch Gelatinization Properties During Development and Maturation of Wheat,Barley and Rye

Changes in starch granule size distribution of wheat, rye and barley during the development were followed with a Coulter Counter. Changes in starch gelatinization properties were determined by DSC-measurements. The “large granules” are laid down in the earliest stage of development and increase in size during the ripening period, even after the appearance of the “small granules”. In the mature grains the proportion of small granules is larger in wheat and rye than in barley. The gelatinization temperature is lower for the mature starch than for starch from an early stage of development. The enthalpy for the gelatinization of the starch increases during development which indicates that the structure of starch granules changes as a result of ripening. The content of amylose-lipid complexes in the starch increases during development, partly depending on the increasing proportion of “small granules”.     

MORPHOLOGY OF STARCH GRANULES IN CEREAL GRAINS AND MALTS

During malting, amylases have limited action on large starch granules of barley endosperm but rapidly degrade the small granules. In contrast, the small starch granules of wheat endosperm are resistant to enzymic attack. High levels of exogenous gibberellic acid increase the production of α-amylase and encourage the appearance of radial channels in the partially-degraded large starch granules. These endo-corroded granules are mainly found in the proximal (embryo) half of the endosperm where levels of α-amylase are much higher than at the distal end. Degradation of malt starch can therefore result from enzymic attack both outside and inside the granules. Malting of barley reduces the population of small starch granules which are slower to gelatinize than large granules at the infusion mashing temperatures of 65° C. During germination of barley multiple starch granules are rapidly synthesized in single amyloplasts in the scutellum. The endosperm of high amylose barley is devoid of small starch granules and the average size of the large granules is reduced. Steeliness in sorghum is related to the close packing of the starch-protein matrix rather than to unequal distribution of protein. The significance of these results is discussed, particularly in relation to the morphology of starch granules, the nature of their outer covering, the distribution of amylopectin and amylose within the granule, and the site of enzymic attack.     

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.     

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.     

Feinkornstärken und hydrophile Polymere als Komponenten für neue biologisch abbaubare Zweiphasenwerkstoffe für spezielle Anwendungen Teil 1: Separations- und Aufbereitungstechniken für Feinkornstärken von Quinoa und Amaranth

Small Granule Starches and Hydrophilic Polymers as Components for Novel Biodegradable Two-Phase Compounds for Special Applications Part 1: Separation and Refinement Techniques for Small Granule Starches from Amaranth and Quinoa A small technical scale process for the separation and special refinement of small granule starches from amaranth and quinoa seed was developed using basic starch technology and machinery equipment as well as a neutral extraction process with xylanases and other enzymes. By using aqueous alkaline media for starch extraction, instead of water, the native starch structure was irreversibly changed, as indicated by Brabender and RVA peak viscosities as well as damaged starch measurements. The functional properties of these smallest native starch granules (0.5–3.0 μm) were investigated for novel applications in starch-compound products. Extrusion compounding processes for the formation of two-phase compounds from small granule starches and synthetic thermoplastics with polar structure units request native starch structures with high thermal stability.     

The Effect of Physical Damage on Large and Small Barley Starch Granules

Barley starch from a Scottish brewing barley (Golden Promise) has been isolated, purified and fractionated into two populations according to the granule sizes. The effects of physical damage on the two types of granules have been examined by iodine staining, debranching, gel chromatography, viscosity measurements and scanning electron microscopy. The amylose content of large starch granules was slightly greater than that of the small granules and the effect of physical damage did not differ significantly between the two types of granules. Physical damage to both types of granules in the dry state followed by extraction with cold water resulted in the preferential solubilization of low molecular weight amylopectin.     

HEAT-INDUCED STRUCTURAL CHANGES OF SMALL AND LARGE BARLEY STARCH GRANULES

The small granules of barley starch were shown to differ from the large granules both in chemical composition and heat-induced functional properties. The small granules had a higher lipid:amylose ratio and also higher dissociation enthalpy of the amylose-lipid complex than the large granules. This may explain the better stability of amylopectin in the gel of small starch granules as analysed by DSC. The small granules had a 4°C higher gelatinisation temperature than the large granules. During heating up to 90°C, the fraction obtained by aqueous leaching of small granules was mainly amylopectin, whereas the carbohydrate solubilized from large granules was mainly amylose .     

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.     

Effects of Granule Sizes on Physicochemical Properties of Cross‐linked and Acetylated Wheat Starches

Large and small wheat starch granules were used for cross‐linking and acetylation to determine effects of granule sizes on physicochemical properties of the modified starches. The native and cross‐linked starches from the small granules showed higher phosphorus contents than did those from the large granules. However, the level of phosphate substituents in the modified starches was not significantly different between the large and small granules under the same conditions. In contrast, the large granules had a higher reactivity with acetic anhydride than did the small granules. The phosphate group cross‐linked starch (CS), acetylated starch (AS) and acetylated cross‐linked starch (ACS) from the large granules had lower gelatinization temperatures and higher enthalpies than those from the small granules. The paste viscosities of the CSs from the large granules decreased rapidly, whereas those of the AS or ACS increased significantly as compared with those from the small granules. The pastes of cross‐linked starches from the small granules were more stable than those from the large granules, whereas the pastes of AS and ACS from the large and small granules had similar resistance to freeze‐thaw treatment. Scanning electron microscopy (SEM) also showed that the small granules were less damaged after modification than the large ones. Thus, the different granule sizes resulted in different physicochemical properties of starch after modification.     

A CRITICAL EXAMINATION OF PROCEDURES FOR THE ISOLATION OF BARLEY STARCH

A study has been made of the methods available for isolating and purifying barley starch granules. A detailed examination involving light and scanning electron microscopy and Coulter counter analysis has indicated that discarding the brown protein layer, which appears on top of centrifuged suspensions of crude starch, results in severe loss of small granules. A protocol is suggested whereby this brown layer is purified separately and then added back to the white layer to give representative starch granule preparations without loss of small granules.     

A GEL FILTRATION STUDY ON THE ACTION OF BARLEY α-AMYLASE ISOENZYMES ON GRANULAR STARCH

Small starch granules are hydrolysed better than large granules by barley α-amylase isoenzymes. The major isoenzyme in barley is less active against both types of granules than the minor isoenzyme. Molecular weight distribution analysis of the hydrolysates shows that the action pattern of the two enzymes is almost identical. Though minor differences in the intermediate products are obtained, the major product from both starches is dextrins with a degree of polymerisation of 6–8.     

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.     

四种元麦淀粉粒形态结构与理化性质的比较

为探明不同品种元麦淀粉粒形态结构与理化性质的差异,以通麦6号、苏裸麦2号、青元麦、黑元麦为实验材料,采用扫描电镜观察、X-射线衍射、傅里叶变换远红外光谱等方法研究了这四类元麦淀粉粒形态特征及其理化性质,结果表明:青元麦,苏裸麦2号和通麦6号淀粉颗粒比较光滑,大小比较均匀,大颗粒多为圆饼形,小颗粒多为圆球形。黑元麦颗粒大小不均匀,差异较大。4类元麦的表观直链淀粉含量不同,其中黑元麦的直链淀粉含量显著高于其他品种;黑元麦和苏裸麦2号的B-型淀粉粒较多,通麦6号和青元麦的A-型淀粉粒较多。黑元麦的淀粉相对结晶度和表层结构有序度最高,溶解度最高、膨胀势最低。在淀粉葡萄糖苷酶水解过程中,青元麦水解程度最高,苏裸麦2号水解程度最低;在猪胰腺α-淀粉酶水解过程中,通麦6号水解程度最高,青元麦最低;在HCl水解过程中,青元麦水解程度最高,黑元麦水解程度最低。     

Inner Structure of Potato Starch Granules

A combination treatment (dry-heat and glucoamylase) was applied on potato starch granules. Many inner granules in the granules after the treatments were observed by SEM. The inner granule located near edge of ellipsoid of granule was partially degraded X-ray diffraction pattern of starch granules did not change before and after the treatments in spite of over 50% loss by amylase digestion. GPC and iodine reaction of the sample showed the treatments brought about fairly large degradation of both amylopectin and amylose components, but GPC of debranched sample after the combination treatments showed amylose was thoroughly degraded while peaks pattern of amylopectin did not change. Small size granules were more susceptible than large size granules by the treatments.