摘要:

AbstractComputer graphics with energy‐minimalization incorporated as a tool in a Biomolecular Program (BMP) helps to develop three‐dimensional structure models for starch components in order to understand the role of conformation in soluti

ISSN:0038-9056    

DOI:10.1002/star.19890410102

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractBei der Umsetzung von 1,4:3,6‐Dianhydro‐D‐sorbit mit Basen und α,ω‐Dihalogenalkanen werden Mono‐ und Dialkylderivate erhalten, mittrans‐1,4‐Dichlor‐2‐buten lassen sich Oligomere bis zum Heptamer isolieren und strukturell zuordnen. Ringöffnende Polymerisationen von substituierten Tetrahydrofuranen mit Supersäuren führen im Falle der 1,4‐Anhydro‐2,3‐di‐O‐alkyl‐D‐erythrite zu funktionalisierten Poly(oxytetramethylenen). Durch detaillierte Studien der Reaktionsparameter lassen sich optimierte Umsetzungsbedingungen erzielen, und mit polymeranalytischen Untersuchungen werden die linearen S

ISSN:0038-9056    

DOI:10.1002/star.19890410103

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractVital‐Weizenkleber kann durch ausreichend lange Reaktion mit Acrylnitril unter gleichzeitiger Seitenketten‐Desamidierung in alkalischem Milieu mit Ausbeuten von 85 bis 90% in lösliche Modifikationen übergeführt werden, die sich als Co‐bindemittel in Papierstreichfarben einsetzen lassen. Als Lösungsmittel wurden Natronlauge und Ammoniak erprobt. Viskosität und Wasserrückhaltevermögen der Streichfarben können in einem weiten Bereich variiert werden. Nach Reaktionszeiten von 18 bis 240 h wurden beim Einsatz cyanethylierter Weizenkleber als Co‐bindemittel sowohl an handgestrichenen Papieren als auch an Papieren aus halbtechnischen Streichversuchen anhand von IGT‐Rupftests Strichfestigkeiten ermittelt, die einem als Co‐bindemittel‐Standard gewählten modifizierten Sojaprotein‐Isolat gleichkamen. Auch in anderen Eigenschaften der gestrichenen Papiere (Glanz, Weißgrad, Naßrupffestigkeit) erwiesen sich die modifizierten Weizenkleber dem Standard als gleichwertig. Orientierende Versuche zur Modifizierung mit Bernsteinsäureanhydrid brachten gleichfalls positive Ergebnisse.Vital‐Weizenkleber sowie die Kleberfraktionen Gliadin und Glutenin konnten zur Verbesserung der Festigkeit von Sperrholzverleimungen eingesetzt werden, wenn sie in Harnstoff‐Formaldehydharz‐Leimen als Streckmittel eingearbeitet wurden.Mit Essigsäure behandelter Weizenkleber läßt sich nach einer Plastifizierung durch intensive mechanische Bearbeitung problemlos zur Streckung von Kollagen verwenden, das als Grundstoff von künstlichen eßbaren Wursthäuten dient. Qualitä

ISSN:0038-9056    

DOI:10.1002/star.19890410104

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractChickpea and germinated chickpea starches were isolated and studied to identify changes in starch attributable to the germination process. They were characterized through physicochemical properties, digestibility in vitro, and appearance in scanning electron photomicrographs. Iodine binding capacity did not change significantly, indicating retention of the amylose/amylopectin ratio during germination. The gelatinization temperature range decreased sharply from 63–70°C to 55–63°C, however, suggesting important changes in intragranular structure. Water binding capacity increased more than 17%, and acidity increased from pH 5.9 to 5.2. Germination sharply increased the susceptibility of chickpea starch to digestibility by α‐amylase, but no change in the appearance of scanning electron micrographs could be attributed to ger

ISSN:0038-9056    

DOI:10.1002/star.19890410105

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractKinetic results are presented for the hydroxyethylation of potato starch with ethylene oxide. The reactions were carried out at 303.0 K in alkaline aqueous starch slurries containing sodium sulphate as swelling inhibitor. A new side reaction was discovered: the formation of hydroxyethyl hydrogen sulphate from ethylene oxide and sulphate dianions. Part of the ethylene oxide is hydrolysed to ethylene glycol. Selectivities were determined by analysis of the products hydroxyethyl starch and ethylene glycol. Since hydroxide ions are formed in the production of hydroxyethyl hydrogen sulphate, the rate of formation of this compound could be measured by the amount of acid added to keep the pH constant. The hydrolysis of ethylene oxide towards ethylene glycol can be described by two parallel reactions: (a) by water, and (b) catalyzed by hydroxide ions. The reaction of ethylene oxide with starch is more enhanced by alkali than the base catalyzed reaction of ethylene oxide with water to ethylene glycol, causing the selectivity of the hydroxyethylation to increase from 7 to 68% if the sodium hydroxide dose is increased from zero to 0.060 mole per mole of anhydroglucose units.

ISSN:0038-9056    

DOI:10.1002/star.19890410106

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe extractability of palmitic and other common fatty acids from inclusion complexes with potato amylose was studied using a wide range of common lipid solvents. At ambient temperature negligible yields were obtained with light petroleum or diethyl ether, and yields were low with most other solvents except those containing methanol or water. At 100°C, methanol, ethanol and propanol and all alcohol‐water mixtures gave good yields. Complexes of amylose with 1‐O‐palmitoyllysophosphatidylcholine also gave good yields when extracted with propanol‐water (3:1) at 100°C. Since more rigorous conditions are required for extraction of lipids from native cereal starch granules, it seems that the barrier to lipid extraction is the structure of the granule rather than the resistance to lipid extraction of any possible inclusion complexes in the

ISSN:0038-9056    

DOI:10.1002/star.19890410107

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractCationic starches are widely used as wet end additives in paper making. They provide many benefits, classified into 4 categories: improvement of mechanical strength; better retention of fines and fillers; faster drainage; reduction of waste water pollution.According to the accepted theory, a 2‐part electrical layer is formed at the solid liquid interface. The zeta potential (existing at the interface between the 2 layers) is one important parameter which influences the retention of most ionic wet‐end chemicals and governs many of the processes involved in making a functional paper product. Practical experiences showed us how to influence the zeta potential in order to obtain the desired benefits. The parameters depending on starch, which have been examined, are: the type of starch (origin), the level of addition and where it is used in the paper making process. Other influences come from the alum content, pH, occurance of shear forces and the presence of dissolved anionic material. Comparative laboratory tests have led to a better understanding of the rather complex interactions on which cationic activity is based. In this paper also the application of cationic starch in surface sizing compared to other starch modifications is discussed. Some important advantages, such as lower waste water pollution and better mechanical strength for the same pick‐up, are cl

ISSN:0038-9056    

DOI:10.1002/star.19890410108

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19890410109

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19890410110

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19890410114

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY