摘要:

AbstractA statistical evaluation was made of the pasting profiles of starches registered with the Brabender Viskograph and the Rapid Visco Analyser (RVA). Fourteen sets of native and modified starches, with a total of 71 samples, were tested in both instruments at the same concentration. When starch samples with only slightly different pasting profiles were measured, e.g., in quality control, the Brabender Viskograph remains the first choice because of its better discriminating ability. For most of the modified starches, good correlations between both instruments were obtained for the viscosity data. When different concentrations were used in both instruments, which is common practice, correlation of viscosity data was poor for those sets, in which the order of viscosities varied as a function of concentration. Correlation of the temperature data was poor. In many cases, the Brabender analysis can be appreciably shortened because of the good correlation between peak and end viscosities.

ISSN:0038-9056    

DOI:10.1002/star.19970490302

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractShear degradation of starch suspensions prepared in the Brabender Viskograph and the Rapid Visco Analyser (RVA) was examined by means of dynamic rheological and steady shear measurements. Generally, it is assumed that more shear is induced in the RVA because of its paddle geometry and its higher rotating speed. However, for a selected set of native and modified starches the pasting preparation in the RVA was accompanied with less shear degradation than the treatment in the Brabender Viskograph. This was mainly due to the much shorter time of treatment in the RVA. When starch suspensions in both instruments were cooked using the same temperature‐time profile, comparable rheological properties were obtained for almost all starch samples investigated. This suggests that the shear conditions in both instruments are quite similar. The rheological properties of starch pastes prepared in the Brabender Viskograph and the RVA appear to be largely dependent on the pasting time, and less dependent on the way in which the shear was applie

ISSN:0038-9056    

DOI:10.1002/star.19970490303

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractStarches from potato (Mainechip, ND651‐9 and Commercial) and Navy and Pinto bean were isolated and the pasting and thermal properties examined. Analysis by Rapid Visco‐Analyzer (RVA) showed potato starches had lower pasting temperatures, higher peak viscosity, and lower setback than bean starches. High intrinsic viscosity values obtained for the potato starch indicated higher average molecular weight for the potato starches compared to the bean starches. Characterization of thermal (gelatinization and retrogradation) properties of starches by Differential Scanning Calorimetry (DSC) showed that potato starches had sharp, well‐defined gelatinization thermograms, while bean starches had broad, shallow thermograms with higher peak temperature (Tp). Potato starches required higher gelatinization enthalpies than bean starches. In comparison with gelatinization, the retrogradation thermograms of starches stored at three different temperatures (23,4 and −10°C) were broader and occurred at the lower temperatures. Compared to potato starches, Navy and pinto bean starches showed a higher retrogradation enthalpy at 4 and 23°C storage temperatures, but a lower enthalpy

ISSN:0038-9056    

DOI:10.1002/star.19970490304

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractStarch isolated from two varieties of sorghum; white and dark grain, have been examined and compared for chemical, physical, physicochemical and rheological properties. Additionally, this study tested starch isolation laboratory scale method for dark sorghum grain. The levels of crude protein, crude fat and ash contents were lower in white sorghum than in dark sorghum starch. No difference was observed between apparent amylose content in both starches. The physicochemical and rheological behavior reveals differences in functional properties and it can be attributed to isolation procedures.

ISSN:0038-9056    

DOI:10.1002/star.19970490305

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractIndustrially prepared wheat starch granules were stained with the fluorochrome Nile Blue A, and subjected to digestion with human saliva. Using a confocal microscope, the degradation of two granules was recorded in sets of optical sections gathered over a seven hour period. Each set of these optical sections was digitally processed to produce a reconstructed 3 dimensional image of the starch granules. Using this technique it was therefore possible to follow the internal and external digestion of each wheat starch granule in real time.

ISSN:0038-9056    

DOI:10.1002/star.19970490306

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractCyclodextrin glycosyltransferase (CGTase) was produced in recombinantEscherichia coliwhich contains thecgtgene ofBacillus maceransin the pTCGT1 plasmid. Antiserum against CGTase was prepared in rabbits. Anti‐CGTase IgG in Serum was purified using an immobilized Protein A affinity column and an immobilizedE. colicell lysate affinity column. The purified anti‐CGTase IgG was coupled to Sepharose4B(5.3mg IgG/mL gel), which was activated with cyanogen bromide. Crude CGTase was purified with this immunoadsorbent with CGTase binding capacity of 0.27 mg/mL and eluted with 0.1M glycine buffer, pH 10.6. Approximately 65% of enzyme activity was recovered from the crude CGTase preparation by this method. The purified CGTase was electrophoretically and antigenically homogeneous, appearing as a single band. After 10 cycles, the recovery yield was not reduced significantly. There was no cross reaction between anti‐CGTase IgG and other tested amylolytic enzymes. This immunoaffinity column is, therefore, effective, efficient, and convenient to use, and can be used widely to purify CGTase from various so

ISSN:0038-9056    

DOI:10.1002/star.19970490307

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe succinylation of cornstarch by extrusion processing has been studied. Several different factors affecting the succinylation of starch were investigated including water content, succinic anhydride quantity, catalyst type and quantity, and reaction temperature. The degree of substitution (DS) increases with decreasing water content and increasing succinic anhydride quantity. Higher temperature favors higher DS using sodium bicarbonate as catalyst while the opposite is true using magnesium hydroxide as catalyst. Of the three catalysts used, sodium bicarbonate is best. Aqueous solubility and viscosity of the starch succinates tend to increase with increasing DS. Based on the results of aqueous solution viscosity, some samples appear to be promising as commercial thickening agent.

ISSN:0038-9056    

DOI:10.1002/star.19970490308

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970490309

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970490310

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970490311

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY