摘要:

AbstractFreshly prepared starch (from potatoes P, from maize M) was separated quantitavely into amyloses and amylopectins under mild conditions. Furthermore, glycogen (G) was extracted from livers of rabbits under observation of physiological provisoes (feeding, rapid removal of the organ under anaesthetic and freezing‐stop). The molecular weights, determined by analytical ultracentrifuge.The side‐chain parts of the amylopectins and of the liver glycogen which were checked by partial enzymatic break‐down into β‐dextrin by β‐amylase (EC 3.2.1.2) and into the basic structure by pullulanase (EC 3.2.1.41) is 64% for P, 62.7% for M, and 65.4% for G. The lengths of the side‐chains, expressed in glucoside residues, are calculated at 12.0 for P and M, and 8.0 for G; the intervals between the side‐chains are 7.0 for P and M, and 4.0 for G. Sources of error with respect to the lengths of and to the intervals between the side‐chains are, firstly, free‐ending, undecomposed side‐chains inside the big molecules which cannot be reached by the two enzymes because fo steric obstruction, and, secondly, the degree of ramification of the basic structures and, consequently, the number of α‐1,4 and α‐1,6‐bound glucoside residues which canno

ISSN:0038-9056    

DOI:10.1002/star.19900421002

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractPotato starch granules which had been lintnerized for 10 d in 2.2 N HCL at 35°C, embedded in Nanoplast and cross sectioned with a low angle diamond knife having an angle of 33.7° have been studied by electron diffraction. The sections were apparently defect free. When they were surveyed under frozen hydrated conditions by transmission electron microscopy in diffraction mode, they gave electron diffractograms typical of B starch. Central sections gave fiber diagrams, whereas noncentral or tangential sections gave strongly arced or even continuous ring diagrams. This technique, if it can be extended to other starch systems, will enable more detailed studies to be made of the crystalline ultrastructure of starch and the organization of the amylose fragments within the starch granul

ISSN:0038-9056    

DOI:10.1002/star.19900421003

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThixotropic behaviour of starch, gelatin and mixed starch/gelatin gels was investigated by different rheological methods by means of the rotational viscosimeter with coaxial cylinders. Influence of different factors (gel composition, preparation temperature, gel age, homogenization and viscosimeter rotor acceleration) on the coefficients of thixotropy and parameters of the flow equation was considered. The recovery of destructed gels was followed byDoherty‐Hurdmethod, but also a modified method was developed and applied for determination of some specificities in the rheological behaviour of starch and gelatin gel

ISSN:0038-9056    

DOI:10.1002/star.19900421004

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

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 f

ISSN:0038-9056    

DOI:10.1002/star.19900421005

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

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 wi

ISSN:0038-9056    

DOI:10.1002/star.19900421006

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA detailed study has been conducted on the action of starch hydrolyzing enzymes from thermophilic anaerobic bacteria belonging to the generaClostridium, ThermoanaerobacterandThermobacteroides. The appearance of multiple bands on polyacrylamide gels with amylolytic as well as pullulytic activities was shown to be a general feature of bacteria investigated. Analysis of the hydrolysis products of each protein band clearly demonstrated the capability of these organisms to hydrolyze α‐1,4‐glycosidic bonds in linear oligosaccharides and α‐1,6‐glycosidic linkages in pullulan. Furthermore, the enzyme system of thermophilic bacteria investigated was also capable of attacking the α‐1,6‐linkages in branched oligosaccharides. Due to the action of these thermoactive enzymes with multiple specificity an almost complete hydrolysis of raw starch and maltodextrin could be achieved under the same conditions a

ISSN:0038-9056    

DOI:10.1002/star.19900421007

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractTwo amylases of an alkalopsychrotrophicMicrococcuswere purified by chromatographies of DEAE‐Toyopearl, Butyl‐Toyopearl and Shodex WS‐2003. Molecular weights and pI values of the purified enzymes, I and II, were 185000 and 125000 by SDS‐PAGE and 4.8 and 4.3 by isoelectric focusing, respectively. Enzyme I had not only amylase but also pullulanase activity. In the presence of Ca2+ions, other properties of both enzymes were very similar: optimum temperature 55–60°C, optimum pH 7.5–8.0 kmvalue for maltopentaose 0.09 mM. Both amylases were completely inactivated after incubation with EDTA at 30°C and thereafter, could be reactivated by an addition of CaCl2. In the absence of Ca2+ions, amylase I became thermoresistant, while the thermostability of amylase II decreased. Neither amylase activity of enzyme I nor enzyme II was inhibite

ISSN:0038-9056    

DOI:10.1002/star.19900421008

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900421009

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900421010

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900421011

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY