摘要:

AbstractA 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 treatme

ISSN:0038-9056    

DOI:10.1002/star.19970491002

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractBei der Anwendung des semi‐dry Prozesses zur Säuremodifizierung der Stärke wird die granuläre Substanz in einem Mischer mit Säure in katalytischer Konzentration besprüht, danach kurzzeitig im Mikrowellenfeld gezielt erhitzt, anschließend durch Aufsprühen einer Sodalösung neutralisiert und gleichzeitig gekühlt.Im Verlauf der milden Säurehydrolyse werden unspezifisch glycosidische Bedingungen der Glucosepolymere gespalten, wovon die Amylopektinfraktion zunächst stärker betroffen ist als die Amylose. Durch die Variation der Modifizierungsbedingungen, insbesondere hinsichtlich der Katalysatormenge und der Erhitzung, ließen sich unterschiedliche Typen dünnkochender Stärke mit variablen Gelbildungseigenschaften bis hin zu reversibel gelbildenden Dextrinen herstellen, die sich gut als Fettreplacer eignen.Der semi‐dry Prozeß ist besonders umweltfreundlich und bietet gegenüber dem gebräuchlichen Slurry‐Verfahren entscheidende Vorteile: eine kleinere Chemikalienmenge, eine kürzere Reaktionsdauer, kein Auswaschen, kein Abwass

ISSN:0038-9056    

DOI:10.1002/star.19970491003

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe dissolution of a cationic potato amylopectin was studied at low dissolution temperatures 50°–97°C. The dissolution was followed by two methods: (1) iodine binding and (2) the flocculation efficiency with nanosized silica particles. The first method gives us information whether the iodine can penetrate the amylopectin structure or not. The second method gives us qualitative information about the size of the amylopectin molecules. At low dissolution temperatures it was found that the molecular weight of the amylopectin (or aggregate size) was larger than those obtained at higher dissolution temperatures. It was also found that the cationic potato starch only containing amylopectin was easier to dissolve than the cationic starch containing both amylose and amylopec

ISSN:0038-9056    

DOI:10.1002/star.19970491004

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractInitial structure and solubility changes of normal corn and starch granules, dispersed in varying methyl sulfoxide (DMSO) concentrations were investigated by scanning electron microscopy (SEM) and high‐performance size exclusion chromatography (HPSEC). Larger granules from starches held for 6 or 15min and air dried showed increased surface etching with increasing DMSO concentration (0–70%): smaller granules showed surface peeling at 70% DMSO. At 90% DMSO, larger granules fractures into smaller pieces, while smaller granules showed full surface erosion. At 100% DMSO, large chunks eroded off both large and small granules. With 100% DMSO, a sheet‐like layer formed over a mass of ruptured granules during drying, suggesting that in the absence of water, DMSO dissolves part of the granule, forming a viscous solution which may limit further DMSO granule dispersion. Granules processed with critical‐point drying showed additional evidence of attack. HPSEC polymer solubility increased with DMSO concentration (0–90%). At 100% DMSO, however, there was no measured solubility. Similar solubilities for starches held at 6 or 15min (0–90% DMSO) suggest that DMSO may require an external force such as heat to facilitate polymer solubility. More amylopectin of a lower molecular weight was solubilized at 6min, while more amylose was solubilized at 15min. This suggests that granule surfaces were mostly composed of amylopectin under development, while amylose was mostly confined to amorphous regions inside

ISSN:0038-9056    

DOI:10.1002/star.19970491005

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe effects of percentage water content in DMSO/water mixtures on amylose conformation were measured by following changes in specific optical rotation, limiting viscosity number, and13C‐NMR chemical shifts. The temperature dependence of specific optical rotation showed differences in amylose conformation for four ratios of dimethyl suphoxide/water. The changes in limiting viscosity of amylose in different proportions of DMSO/water with increasing temperature, and the effect of tetramethylurea on the specific rotation of amylose, indicate that the number of intramolecular hydrogen bonds decreases with increased water content. An amylose conformational change was also deduced from13C‐NMR chemical shift changes. Thirty‐three percent water appears to be a crossover concentration. above which the helical conformation is progressively lost with increased temperature. With further increase in water conent to 66.6%, transition to a random coil conformation is complete, and iodine complexation may take place. The transition of amylose conformation from helix to loose helix to random coil with increasing water content was deduced from the experimental re

ISSN:0038-9056    

DOI:10.1002/star.19970491006

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe ash content of wheat flour is used to evaluate its quality but the conventional method of analysis takes several hours. This paper proposes using the potassium ion concentration of wheat flour samples instead of the ash content since the correlation between the two is very good (the correlation coefficient was 0.99). A flow injection analysis (FIA) system based on a potassium ion selective electrode took less than 10min per measurement with a coefficient of variation less than 3%.

ISSN:0038-9056    

DOI:10.1002/star.19970491007

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractUse of an aqueous alcoholic‐alkaline solvent allowed cationization and phosphorylation to be combined in simultaneous or sequential processes in the production of amphoteric starch. Degrees of substitution required by the paper industry were obtained in normal corn, pea and barley starches, and in waxy corn and barley starches without the need for drying and heating the cationic starches to complete the phosphorylation reaction. The amphoteric starches had increased welling power, lower gelatinization temperatures, improved paste consistency and stability, and increased α‐amylase digestibility than native controls, while gel syneresis after cold storage was elimin

ISSN:0038-9056    

DOI:10.1002/star.19970491008

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491009

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491010

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491011

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY