bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization on the Conformation of Glucoamylase from Rhizopus niveus and Rhizopus delemar
Authors: Ohnishi Masatake , Higuchi Atsuko , Todoriki Setsuko , Hiromi Keitaro , Ohgushi Wmikio , Wada Akiyoshi 
Published: November 2006

AbstractUsing the pH‐jump (neutral to above 11) for Tyr‐OH ionization as a probe, two glucoamylases from Rhizopus niveus and Rhizopus delemar were found to be caused the change in conformation, which is in a kinetically single step. The pH titration at pHs below 12 was carried out on a multidimensional correlation spectrophotometer. Correlations among the spectrophotometric properties: fluorescence, absorption and circular dichroism are almost identical for the two enzymes. These results suggest that conformational characteristics of the niveus enzyme is almost the same as that of the delemar one.
Estimation of Amylose Content of Starches after Precipitation of Amylopectin by Concanavalin‐A
Authors: Yun Suk‐Hun , Matheson Norman K. 
Published: November 2006

AbstractThe estimation of the amylose content of starches has been studied by precipitating the amylopectin with concanavalin‐A and then, after denaturing the remaining concanvalin‐A by heat, determining the unprecipitated glucan in the supernatant by (a) hydrolysis with amyloglucosidase: α‐amylase followed by glucose oxidase‐peroxidase reagent, (b) colorimetrically with phenol‐sulphuric acid or (c) by colour with iodine.
Changes in Carbohydrate Fractions in Enzyme‐Supplemented Bread and the Potential Relationship to Staling
Authors: Lin Wei , Lineback O. R. 
Published: November 2006

AbstractWhite breads were prepared with and without bacterial α‐amylase. Breads containing α‐amylase became firm (staled) more slowly than did those without the added enzyme. Larger quantities of carbohydrate were extracted from enzyme‐supplemented breads. The additional carbohydrate was mainly branched‐chain material with an average chain length (CL) of 19–24. Thus, the α‐amylase acts on starch during baking to form predominantly branched‐chain polymers of lower molecular weight. These polymers apparently have a decreased ability to retrograde, interfere with the ability of amylopectin to retrograde after the bread is baked, or interfere with other interactions involved in firming, thus reducing the extent of firming (staling).
Study on Interactions of Corn Starch and γ‐Cyclodextrin with Lipid Peroxide
Authors: Komiya T. , Yamada T. , Imai K. , Hisamatsu M. , Masui H. , Kawakishi S. 
Published: November 2006

AbstractThe deterioration of corn starch and γ‐cyclodextrin (γ‐CD) as a model compound by coexisting of methyl linolate (ML) has been studied in the solid system. With the elapse of oxidation time of ML, the reducing values of above the sugars increased and the value of γ‐CD with Silica Gel done more largely than without the one. The molecular weight of corn starch may decrease slightly, the glycosidic linkages of amylopectin and amylose molecules in the starch may be cleaved partially and the crystalline structure of the starch will be deteriorted a little by some active radicals formed by the autoxidation of ML. The propagative autoxidation of ML induced the deterioration of γ‐CD giving the two processes of the hydrolysis and the depolymerization in the similar way as observed in the reaction of γ‐CD with OH radicals.
Physical Characterization of Bromine Oxidised Potato Starch
Authors: Muhrbeck P. , Eliasson A.‐C. , Salomonsson A.‐C. 
Published: November 2006

AbstractNative potato starch and potato starch oxidised with bromine at different concentrations were studied. A successive decrease of the gelatinisation enthalpy and a downward shift in the gelatinisation temperature were observed by the use of differential scanning calorimetry. When the oxidation was followed by a reduction step, those effects were accentuated. The mean molecular weight of the starch diminshed as the concentration of bromine oxidant was increased. In accordance with this, the viscosity of water solutions of corresponding samples successively decreased. However, when samples were reduced after the oxidation step, an increase in the viscosity was observed. A microscopic investigation showed that the granule structure was lost already at the lowest level of oxidation.
Changes of Carbohydrates and Molecular Structure of Dextrins During Enzymatic Hydrolysis of Starch with Maltogenase Participation
Authors: Nebesny E. 
Published: November 2006

AbstractInvestigations of the potato starch hydrolysis during bacterial α‐amylase “BAN 240 L” liquefaction to 19.5 DE and then saccharification with exo‐acting α‐amylase “Maltogenase 1000 L” alone and together with pullulanase “Promozyme 200 L”, were carried out. Under adequate conditions at different enzyme dosages hydrolyzates of the maltose, content of 60 to about 80% in DS at significantly lower glucose and minimal maltotriose content were obtained. Investigations comprised both carbohydrate contents in hydrolyzates, changing with hydrolyse course and dextrin molecular structure in hydrolyzates. It was found that decreasing dextrin molecular weight and the number of branchings in dextrin molecules was accompanied by characteristic changes of the viscosity of hydrolyzate solutions.
Halogen Azide Displacement to Prepare Some Symmetrically Substituted β‐Cyclodextrin Derivatives
Authors: Szurmai Zoltán , Lipták András , Debrecen  , Szejtli József 
Published: November 2006

AbstractThe heptakis (2,3‐di‐O‐acetyl‐6‐bromo‐6‐deoxy)‐β‐cyclodextrin has been converted to the 6‐azido derivate with 82% yield, then deacetylated by the Zemplén's method (yield 75%) and methylated by methyl‐iodide (yield 66%), to heptakis (2,3‐di‐O‐methyl‐6‐azido‐6‐deoxy)‐β‐cyclodextrin, which is an appropriate intermediary toward methylated amino‐CD‐derivatives. The structure of all compounds were unambiguously proven by NMR spectroscopy.
α‐D‐Polyglucane‐Iodine Complexes
Authors: Thorn W. , Mohazzeb S. 
Published: November 2006

AbstractThe temperature‐dependent dyeability of oligoglucanes and polyglucanes with I2/KI solution is based on the interaction between iodine and the C‐atoms of glucosidic bonds (Vetter and Thorn [1, 2]). Only when the helix is compressed, the expansion of the lumen that is necessary for the attachment of iodine bands is achieved as suggested by Freudenberg et al. in 1939 [3].The development of colour starts with the maltododecaosis (just over two spirals) within a temperature range of 20 to 25°C adsorbing one pentaiodide and bringing about a pale shade of pink. The rich blue tone is achieved with pure amyloses forming a maximum of about 610 to 620 nm. Unramified polysaccharides which had been synthesised by our team from 30 glucoside residues, still showed a purple colour with a maximum of 510 nm at temperatures from 20 to 25°C. Defined polysaccharides from 40 residues are bluish‐purple (just 7 spirals of a tension‐free helix) with a maximum absorption of about 550 nm. According to our knowledge, the rich blue tone requires at least 50 glucoside residues linked in an unramified chain [1, 2].Amylopectin from potatoes has a maximum of 575 to 580 nm which shifts to 555 to 560 nm after partial break‐down into β‐dextrin by β‐amylase (EC 3.2.1.2) and does a long‐wave re‐shift to 570 nm after splitting off of the side‐chain stumps in the basic structure by pullulanase (EC 3.2.1.41). In the case of maize, the maximum is 535 nm for amylopectin, 520 nm for β‐dextrin, and 555 nm for the basic structure. This means that in amylopectin from potatoes the helical sections available for the adsorption of iodine bands are longer than those in amylopectin from maize [4]. In glycogen iodine accumulates in a diffuse manner without forming any long bands. For this reason, an absorption shoulder of merely 400 to 500 nm is found by photometry [4].A treatment with β‐amylase makes the situation even worse; only when the side‐chain stumps are separated by pullulanase does the formation of iodine bands in the basic structure of the glycogen improve to a maximum of 500 nm. This maximum corresponds to unramified sections of less than 30 glucoside residues [4, 2, 6].
Enzymic Determination of Starch in Samples with High Sugar Content
Authors: Henry Robert J. , Blakeney Anthony B. , Lance Reginald C. M. 
Published: November 2006

AbstractStarch may be determined by hydrolysis with α‐amylase and amyloglucosidase followed by specific measurement of glucose using glucose oxidase. However biological samples to be analysed for starch often also contain glucose, maltose and higher oligosaccharides derived from the hydrolysis of starch. These sugars may be difficult to remove quantitatively by solvent extraction. We have found that reduction with sodium borohydride followed by evaporation with 2,2 dimethoxypropane removed interference from glucose, maltose and the two reducing terminal residues from higher oligosaccharides. The specific glucose test was not sensitive to glucitol produced by reduction of free glucose. Maltitol was not hydrolysed significantly by the amyloglucosidase, removing interference from maltose and the two reducing terminal residues from higher polymers. The method has potential for monitoring the hydrolysis of starch especially in the mobilisation of starch reserves in plant tissues such as in the endosperm of germinating cereal grains. A reduction ratio based upon the method is proposed for use in characterising starch hydrolysates.
The Effects of Water Soluble Arabinoxylan on Gelatinization and Retrogradation of Starch
Authors: Gudmundsson M. , Eliasson A.‐C. , Bengtsson S. , Aman P. 
Published: November 2006

AbstractThe effects of soluble pentosans, in the form of the main water‐soluble arabinoxylan from rye grain, on the gelatinization and retrogradation of starch were studied. Five different starches, waxy, amylomaize, wheat, maize and potato starches and wheat flour were used. The water contents of the samples varied from 46.5 to 50%. Differential scanning calorimetry (DSC) showed that the arabinoxylan had a negligible effect on the gelatinization. However, the arabinoxylan did affect the retrogradation. The recrystallization process is particularly sensitive to the water content in the sample. The maximum extent of recrystallization occurs when the starch concentration is between 50 and 60%. The effects of the arabinoxylan are probably caused by the water absorption ability of the arabinoxylan. i.e. control of the water availability of the starch which thereby, increases the retrogradation. The effects of arabinoxylan addition are. however, dependent on the initial starch concentration. The results of the rheological measurements agreed with the DSC measurements because potato starch gels (42.–42.8% on dry matter basis (d.b.)), with added (2% d.b.) arabinoxylan, were more rigid after seven days of storage than pure potato starch gels.
Determination of the Posphorylation of Starch from Native Potato Varieties by 31P NMR
Authors: Muhrbeck P. , Tellier C. 
Published: November 2006

Abstract31P NMR technique was used to determine variations between potato varieties in the degree of phosphorylalion on the C‐3 and C‐6 sites of the glucosidyl units of the amylopectin molecules. The C‐3 phosphorylation was independent of the potato variety, while a substantial variation in the C‐6 phosphorylation was observed.
Anreicherung pflanzlicher Inhaltsstoffe durch selektives Trockenzerkleinern und anschließendes Klassieren
Authors: Heideker Hans‐Thomas , Schubert Helmar 
Published: November 2006

AbstractSeit mehreren Jahrzehnten wird über die Anreicherung meist von Protein aus Getreide und Hülsenfrüchten durch trockenes Feinzerkleinern und anschließendes Windsichten berichtet. Im Gegensatz zum bisher rein empirischen Vorgehen behandelt die vorliegende Arbeit die beiden Verfahrensschritte Zerkleinern und Klassieren getrennt voneinander. Dieser Ansatz führt zu einer Gleichung. mit der man eine mechanische Inhaltsstoffverschiebung aus wenigen Versuchsdaten berechnen kann. Experimentelle Untersuchungen zum Verfahrensschritt Zerkleinern ergeben. daß sich bei biologischen Stoffen mit einer Matrix‐Zellstruktur die Art der Beanspruchung durch Druck oder Prall nicht auf die Selektivität der Zerkleinerung auswirkt. Anhand des Arbeitsstoffs Palerbsen wird für die Prallzerkleinerung gezeigt, wie sich Selektivität und Proteinverschiebung mit der Partikelgrößenverteilung des Mehls verändern. Simulationsrechnungen behandeln den Einfluß des Vertfahrensschritts Klassieren auf die Protein‐ und Stärke‐verschiebung. Aus den Ergebnissen der Arbeit folgen Empfehlungen für eine einfachere und zuverlässigere Anvendung des Verfahrens.
Nuclear Magnetic Resonance Studies of Homopolysaccharides Related to Starch
Authors: McIntyre Deane D. , Vogel Hans J. 
Published: November 2006

AbstractOne‐ and two‐dimensional 1H and 13C NMR spectra were obtained for a variety of homopolysaccharides, including the glucans dextran and pullulan, and the fructans levan and inulin. The NMR results provided information about the primary structure of these polysaccharides. Our results are in agreement with those determined previously by methylation analysis and other classical methods. The number of α(1 → 44) and α(1 → 6) linkages could be quantitated for pullulan. The presence of a single nonreducing glucose residue in the polyfructose inulin could also be demonstrated. In the case of the branched polysaccharides dextran and levan, it was possible to determine the degree of branching. In addition for lower molecular weight polysaccharides such as inulin and partially hydrolyzed dextran, it was possible to detect signals arising from reducing and non‐reducing end groups. Their approximate molecular weight could be determined by quantitation of these signals.
The Cationic Distribution in a Cationised Potato Starch
Authors: Salomonsson B. Ann‐Christine , Fransson Gunnel M. B. , Theander Olof 
Published: November 2006

AbstractIn the present study the distribution of cationic groups among the starch fractions, amylose and amylopectin, was investigated to illustrate the reactivity of the two starch components and also to better understand the behaviour of the cationised starch. A quaternary ammonium potato starch was separated in amylose and amylopectin by GPC. The content of nitrogen‐containing substituents in the fractions obtained was analysed by proton NMR and by nitrogen analysis. The sample studied here contained 0.27% nitrogen, made up of 0.21% nitrogen from the amylopectin and 0.06% from the amylose fraction. Thus in the cationic starch studied, with a DS of 0.03, the amylopection was more reactive than the amylose.
Continuous Synthesis of Glucoamylase by Immobilized Fungal Mycelium ofAspergillus niger
Authors: Abraham T. Emilia , Jamuna R. , Bansilal C. Vijay , Ramakrishna S. V. 
Published: November 2006

AbstractThe extracellular glucoamylase enzyme (EC 3.2.1.3) was synthesized continuously by the immobilized mycelial fragments of A. niger. Of the several polymeric matrices attempted for immobilization k‐carrageenan and alginate were found to be the most effective. However, the enzyme activity exhibited by the immobilized mycelia (I.M.) was 15‐20% lower than that of free cells under batch conditions. The immobilized cells have retained nearly the same enzymatic activity (120IU/g of I.M.) for 6 repeated batches and thereafter decline in activity was noticed. An aerated packed bed reactor with I.M. was operated continuously for 360 h. The volumetric productivity of the reactor was 1600IU/L/h for 192 h and reduced to 25% in 360 h.
Evolution of the Structural Representation of Sucrose [1]
Authors: Lichtenthaler Frieder W. , Immel Stefan , Kreis Uwe 
Published: November 2006

AbstractFollowing a historical account on the establishment of the constitutional formula of sucrose and of its conformational features, the present possibilities for interactive graphics display of its molecular geometry, based on X‐ray structural data, are given. In addition, the MOLCAD program‐computed contact surface is presented as well as ‐ in a 16 color code ranging from violet ro red ‐ the electrostatic potential and, most relevant for structure‐sweetness relationship considerations, ist hydrophobicity potential profile on the contact surface. Finally, an attempt is made towards a tentative assessment of the computer‐generated distribution of hydrophilic and hydrophobic regions over the surface of the sucrose molecule in terms of the “sweetness triangle” AH‐B‐X concept. Also given are the graphic displays for the contact surfaces and hydrophobicity profiles of leucrose, isomaltulose and its reduction products α‐glucosyl‐mannitol and ‐sorbitol.
Encapsulation of EPTC in Starch by Twin‐screw Extrusion
Authors: Trimnell D. , Carr M. E. , Doane W. M. 
Published: November 2006

AbstractA twin‐screw extruder was used for encapsulation of the herbicide EPTC (S‐ethyl dipropylcarbamothioate) in starch. Three starch/water ratios, 35/65, 50/50, and 65/35, were evaluated for efficiency to encapsulate 13.9% EPTC on a dry starch basis. Analysis of extrudates, after drying and grinding to the desired particle size, showed recovery of active ingredient (a.i.) and effectiveness of encapsulation to be best at 35% starch solids (35/65 starch/water ratio). Scanning electron micrographs showed smaller and a more even distribution of a.i. at 35% starch. Suspending particles in water caused a release of EPTC which increased with agitation and smaller mesh size. Air‐dried particles released EPTC more slowly than oven‐dried particles of the same mesh range. Particles from extrusion at 35% solids released a.i. more slowly than those from extrusion at 65% solids. The slowest releasing particles showed the least swellibility. EPTC was also encapsulated at 10.2% a.i. using 20% and 35% starch solids with steam‐injection cooking followed by Sigma blade mixing for comparison with an extrusion. Herbicide retention and encapsulation were superior, release of a.i. into water was slower, and swelling of particles was less in twin‐screw extrusion prepared products.
Rheological Studies on Potato Starch Pastes at Low Concentrations. Part IV: Absolute Measurements of the Rheological Properties of Starch During Gelatinization
Authors: Janas Piotr 
Published: November 2006

AbstractThe method of absolute measurement of the rheological properties of starch suspensions during gelatinization is presented. It enables to determine the flow curves already in the early stage of the process. The studies were carried out on 1.5% aqueous suspension of potato starch. They have shown that just at the temperature of approximately 15°C above the beginning of gelatinization the formed paste starts to behave as a shear‐thinning liquid with the yield stress, τy. The non‐ Newtonian effects increase as the temperature increases. Experimental data are satisfactorily described by the modified four‐parameter power law: τ = τy + τ0(γ˙/γ˙0)n. The temperature dependences of n‐ and τy‐parameters univocally determine the evolution of rheological properties which are observed on experiment. This evolution is understood as the transformation of Newtonian liquid through a pseudoplastic liquid into a nonlinear viscoplastic one.
Determination of Glucoamylase Activity with Glucose Electrode
Authors: Przybyt Malgorzata 
Published: November 2006

AbstractThe method of glucoamylase activity assay by oxygen electrode with immobilized glucose oxidase is described. The optimal conditions of assay were established and are following: 1% starch, pH 4.5, and 25°C. The method could be applied to kinetic measurements of glucoamylase action on starch. The results of such investigations are similar to obtained earlier by chemical method. The method could be used for assay of glucoamylase activity in the presence of α‐amylase by changing the pH of solution to 7.
A Characterization of Faba Bean Starch (Vicia faba L.)
Authors: Haase Norbert U. , Shi Hai Lin 
Published: November 2006

AbstractIn Far East faba bean starch is always present in several food applications. But often the starch quality is low and knowledge of characteristic attributes do not exist. Therefore, we tried to isolate a faba bean starch with few impurities, and to analyse the starch quality with different types of techniques. Furthermore, a comparison between three cultivars (two Chinese and one German) should point to possible differences.The crude protein content of all isolated starches was lower than 0.3% dry matter. Particle size distribution of the starch granules was mainly between 20 and 40 μm diameter. Gelatinization range was between 56 and 81°C. Brabender viscograms showed very stable hot gels with no viscosity reduction during the hot phase. A gel filtration analysis of the starch molecules gave relevance to molecular weights of amylose between 100 and 200 × 103 MW. In spite of quite different genetic backgrounds and agricultural conditions the quality of the starches was not very different between the two Chinese and one German cultivars.
Spectrophotometry on the Change in Conformation of Bacterial Alpha‐amylase, Characterized with 6m Urea
Authors: Iwata Ken , Hiromi Keitaro , Ohnishi Masatake 
Published: November 2006

AbstractChange in conformation of bacterial alpha‐amylase (Bacillus subtilis, liquefying, BLA), induced with 6m urea, was observed on difference absorption‐ and optical rotation spectrophotometries as probes. Time courses of the latter were coincident with those of the former for the whole time range examined (‐110min). BLA‐catalyzed activity in 6m urea, the third probe, was found to show a biphasic time‐course. Phase I and Phase II, and to be lost at Phase II: Phase I is tolerant against the urea‐induced change in conformation. Hence, the active site may be conservative in an enzyme engineering on the BLA molecule.
Glucoamylase Covalently Bound to Acrylic Carriers
Authors: Wawrzyniak B. , Krauze J. 
Published: November 2006

AbstractGlucoamylase from Aspergillus niger was covalantly bound to three acrylic carriers differing in the content of amino groups, particle size, porosity, etc. Yield of immobilization ranged from 58.7% to 87.0%. Enzyme immobilized on Vinylaff 818 was the most stable. That carrier was a copolymer of butyl acrylate and ethylene dimethacrylate, containing 0.44 mmol/g of amino groups.The immobilized catalyst used for hydrolysis of 40% maltodextrin solution (DE 18.3) retained its initial activity at 50°C for about 33 d. The pretreatment of soluble glucoamylase with low concentrated glutaraldehyde solution (0.13%, 1.4 mg/100 mg of protein) increased the operational stability of immobilized enzyme to about 50 d and its half‐life to 60 d.The immobilization of enzyme on Vinylaff 818 resulted in the slight shift of pH optimum to acid side, though it did not influence the temperature optimum. Thermostability of immobilized glucoamylase in the range of temperature between 50 and 75°C was higher than that of soluble enzyme. Maximum concentrations of glucose in hydrolyzates were obtained in relatively short time. The prolonged hydrolysis of concentrated starch substrate by enzyme immobilized on the porous carrier caused, however, the accumulation of disaccharides with simultaneous reduction of glucose content.
Progress in the Enzymatic Saccharification of Wheat Starch
Authors: Konieczny‐Janda G. , Richter G. 
Published: November 2006

AbstractProblems were noticed when trying to include wheat starch to the normal liquefaction and saccharification lines because of the formation of precipitations which are difficult to filter. The effects of different side activities of Aspergillus niger glucoamylases on the filterability of wheat syrups are demonstrated. In order to speed up filtration, viscosity has to be decreased by degradation of arabinoxylanes with present pentosanes. A new enzyme has been discovered which is able to split partially the lysophospholipids contained in wheat starch and let the insoluble components flocculate to big particles. This enzyme splits the phospholipids into free fatty acids and glycerophophorylcholines. The properties of this enzyme present in a novel glucoamylase preparation for the wheat starch processing are demonstrated by using an HPLC method, showing the degradation of wheat lipids as well as synthetic lysophopholipids.