摘要:

AbstractA rapid, semi‐micro method has been developed for the estimation of the amount of starch in cereal grains. The method is suitable for samples of flour in the range 7.5–20 mg, and hence the amount of starch in a single grain can be readily determined. The procedure – which is given in detail – involves first solubilizing the starch by hot aqueous calcium chloride, and then subjecting the extract to the concurrent action of a‐amylase and amyloglucosidase. A quantitative determination of the resultant glucose is then made by the use of glucose oxidase. Relatively few manipulations are involved.This technique is applicable to a wide range of cereals, including the high‐amylose‐content, genetic mutants of maize. The method has a reproduceability of ± 1.5 %.The new procedure has been compared with methods based on polarimetry and perchloric a

ISSN:0038-9056    

DOI:10.1002/star.19700220402

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractVarious pretreatment methods for starch were applied to a commercial high‐amylose corn starch of apparent 71% amylose content before acetylation in acetic anhydride‐pyridine at 100°C. Pretreatments that involved major granule disintegration, such as solubilization of the starch in DMSO or agitation in hot water followed by precipitation of the starches with ethanol and drying, were most effective for obtaining rapid and complete acetylation without degradation. The resulting triacetates, in contrast to the others, were completely soluble in chlorinated hydrocarbon solvents and therefore would be preferred for film and fiber prepara

ISSN:0038-9056    

DOI:10.1002/star.19700220403

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractOn the Quantitative Determination of Sorbitol by Oxydative Splitting by Means of Periodic Acid.The oxydative splitting reaction of polyhydroxy compounds with vicinal hydroxyl groups by means of periodic acid or periodates can be applied with advantage to the determination of sorbitol concentration, especially in case of working with simple equipment.The oxydative splitting reaction leads to three reactive substances which can be determined by iodometric or acidimetric titration, i.e. a) remaining periodate, b) formaldehyde, and c) formic acid. The practicability of the three resulting methods of determination has been examined with three different commercial samples of sorbitol.The mathematic‐statistical interpreted data show that only the determination of remaining periodate leads to results which are in accordance with the theoretical sorbitol concentratio

ISSN:0038-9056    

DOI:10.1002/star.19700220404

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractThe role of amylase inhibitors on the liquefaction of starch in maize is discussed. Experiments with a Brabender Amylograph and a Votator continuous cooker for investigating the influence of proteolysis and amylase inhibitors are briefly discussed. Results indicated that excellent yields of sugar could be obtained by pretreating a 30% suspension of maize grits in water in the Votator apparatus at pressures of about 200 lb. p.s.i. before hydrolysing with amylolytic enzymes at this pressure.

ISSN:0038-9056    

DOI:10.1002/star.19700220405

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractOn the Rheology of Aqueous Systems on the Basis of Gums.The water „solutions”︁ of macromolecular carbohydrates (arabic gum, alginate, guaran, starches) often show a non‐Newtonian behaviour. Therefore it is impossible to give only one viscosity value for the definition of the rheological behaviour; viscosity changes with the different rheological conditions. But it is possible to speak of an „apparent viscosity”︁ for a given shear rate Dior stress ri. To characterize the rheological behaviour it is necessary to establish the relationship between shear rate and shear stress. Sometimes, for limited decades of shear rates, the behaviour may be described by a power law = τ =KDa: sometimes the Cross relation\documentclass{article}\pagestyle{empty}\begin{document}$ \overline \eta = \eta _\infty + \frac{{\eta _0 - \eta _\infty}}{{1 + \alpha D^{2/3}}} $\end{document}has to be applied; but it may also occur, that one can only give the curve log τ = f (log D). To obtain absolute values it is necessary to apply a correcting factor at the actual values given by Newtonian approximation. Thus it is possible to study the influence of temperature, concentration and ageing on the rheological parameters K, a, η or the graph log τ = f (log D).From the results it seems that the behaviour of this kind of systems is rather like the behaviour of emulsions, than like that of true solutions.Perhaps that is the reason why, the process for the preparation of these systems has to be well defined and rigorously followed in order to obtain reproducible results.To give a sense to rheological studies in the laboratory, it is important to simulate the exact industrial conditions of preparations and of the rheological stresses of these systems. This calls for an exact knowledge of the industrial rheological stress; up to now this knowledge is very r

ISSN:0038-9056    

DOI:10.1002/star.19700220406

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractJack bean (Canavalia ensiformis) starch is composed of granules measuring up to 37 micra. Gelatinization temperatures of the granules range from 67.5 to 78 °C. Its pastes, in concentrations up to 6 % did not show swelling peak which appears only in high concentrations. They are very stable during stirring, both at low and high temperatures. They are also more resistant to α‐amylase bacterial action than those of corn starch.The results, both for granules and pastes of this starch, show a great resemblance with the same data for guandu b

ISSN:0038-9056    

DOI:10.1002/star.19700220407

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractA large variety of cooked corn products can be prepared on rolls, in extruders or by steamcooking. Slight changes in operating conditions of the cooking equipment can bring about significant changes in absorption, solubility and viscosity properties of the cooked products. Production of processed materials with high water absorption and retaining high cooked paste viscosity appears more difficult by direct steaming than by use of the other methods.Roll‐cooking should be better than extrusion‐cooking for preparing materials of maximum water absorption and minimum water solubility. Such materials are well suited either for thick gruels or for industrial thickening or gelling agents. Extrusion‐cooking should be better for preparing materials of minimum water absorption and maximum water solubility. Such materials are well suited either for beverages or for industrial uses where adhesive properties are desired. Steamcooking should be suitable for preconditioning before roll‐ or extrusion‐cooking, but it appears that heating time must be held to

ISSN:0038-9056    

DOI:10.1002/star.19700220408

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

摘要:

AbstractOn the State of Knowledges Concerning the Processes During Staling of Starch in Baked Goods.1. The present level of knowledge on staling of baked goods is discussed shortly on the example of most essential theories. 2. Research into the problem of staling of gels of wheat starch or wheat flour was performed viscographically and ridgelimetrically. 3. The photometric titration with iodine and the paper elution analysis with perchloric acid are recommended as new methods for a separated characterization of the starch constituents during staling. 4. In the staling of baked goods, the changes of starch play a predominate role, the swelling condition of the starch granule and the chemo‐physical and chemo‐colloidal behavior of the two starch constituents being decisive factors. 5. The natural fat content of flour or the addition of saccharose monostearate counteract the hardening of the corresponding gels, caused by staling, by inhibiting the swelling process of the starch granules and the effect of amylose on the formation of struct

ISSN:0038-9056    

DOI:10.1002/star.19700220409

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19700220410

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19700220411

出版商:WILEY‐VCH Verlag GmbH    

年代:1970

数据来源: WILEY