摘要:

AbstractThe view that starch exhibits ionic features is applied to the process used to make ungelatinized starch derivatives. This leads to some simple experiments, which reveal the validity of that theory. The statement that the anions are the actual gelatinizing agents is substantiated by experimental evidence.

ISSN:0038-9056    

DOI:10.1002/star.19900420902

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractEs wird eine methodische Vorgehensweise vorgestellt, mit der die systemanalytische Untersuchung des Einflusses der Extrusionsbedingungen auf den Verlauf der Derivatisierung von Kartoffelstärke zu kationischer Stärke und zu Carboxymethylstärke untersucht wird. Die Vorgehensweise lehnt sich an eine für die Extrusion von Stärke und stärkehaltige Rohstoffe entwickelte systemanalytische Betrachtung des Extrusionsvorgangs an. Mit Hilfe von Regressionsrechnungen wird gezeigt, daß auch bei der Derivatisierung der Stärke ein funktionaler Zusammenhang zwischen den Prozeß‐ und den wichtigsten Systemparametern (Produkttemperatur, spezifische mechanische Energieeinleitung, mittlere Verweilzeit) besteht. Mit diesen drei Systemparametern allein kann jedoch der Zusammenhang zwischen den Systemparametern und den Strukturparametern, wobei hier insbesondere der Wirkungsgrad der chemischen Reaktion (R. E.) als bedeutender Strukturparameter untersucht wurde, nicht beschrieben werden. Eine Korrelationsrechnung mit dem Wassergehalt als viertem Systemparameter resultierte in einer hinreichend genauen Beschreibung der funktionalen Beziehung zwischen den Systemparametern und der R. E., von welcher der Substitutionsgrad direkt abhängt. Diese vierdimensionale Abhängigkeit läßt sich jedoch graphisch nicht darstellen. Deshalb wurde die weiterführende systemanalytische Betrachtung zunächst unter der Voraussetzung eines konstanten Wassergehalts durchgeführt. Im Sinne des beschriebenen systemanalytischen Modells wurde als exemplarische physikalisch‐chemische Eigenschaft der durch Extrusion hergestellten Derivate die Kaltkleisterviskosität (KKV) in die Betrachtung miteinbezogen. Mit dem Ziel, Extrusionsbedingungen zu finden, die eine maximale R. E. ermöglichen, wurde die graphische Darstellung der Abhängigkeit der R. E. von den Systemparametern über das untersuchte Versuchsfeld hinaus extrapoliert. Kontrollversuche zeigten jedoch, daß die erhaltenen Regressionsgleichungen die Verhältnisse außerhalb des untersuchten Bereiches nicht hin

ISSN:0038-9056    

DOI:10.1002/star.19900420903

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe comparison of starch granule deformation and extent of starch gelatinization in a few common Indian unleavened flat breads (Chapati, Parontha and Poorie) was made. The starch granule swelling was evaluated by scanning electron as well as polarized light microscopy. The peak viscosity in Haake rotary viscosimeter and hydration capacity were used for comparing the extent of starch gelatinization in crust and crumb of these baked products. Although a few of the starch granules on the outside of crust, maintained a weak outline those in the crumb area gave only a matrix of gelatinized starch. The extent of starch gelatinization was reflected by the related increase in hydration capacity of these products. However, the peak viscosity values were found to be inversely related to the extent of starch gelatinization. As compared to crumb, a higher extent of browning was observed in the crust. Water absorption, type of cereal, mode and efficiency of heat transfer were found to control the extent of starch gelatinization in these baked products.

ISSN:0038-9056    

DOI:10.1002/star.19900420904

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractD‐Glucose (“dextrose”) is a building unit of starch, cellulose, sucrose and lactose. For technical and economical reasons D‐glucose is produced on large industrial scale by enzymatic hydrolysis of starch. Main use is for nutrition, as feedstock for sorbitol and HFCS (high fructose corn syrup) and as carbon source for industrial fermentations. For broader industrial use of D‐glucose, problems of selectivity, pH‐ and temperature instability and insolubility in organic solvents have to be overcome. Selective chemical and biotechnical transformations, preferably in water, are necessary and favourable intrinsic properties like biodegradability, biocompatibility and chirality have to be exploited.This paper will review/preview existing knowledge and experience on possibilities to oxidise selectivity the different hydroxyl functions at positions C1 to C6 of unprotected D‐glucopyranose in water as solvent, using biotechnical catalysts (microbial cells, enzymes) or heterogenous chemical catalysts.Transformations to the following oxidised D‐glucose derivatives will be covered.Glucosone (2‐keto‐D‐glucose), 6‐aldehydo‐D‐glucose, D‐gluconic‐acid, D‐glucuronic acid, 2‐keto‐L‐gulonic acid, D‐glucaric acid, 2‐keto‐D‐gluconic acid, 5‐keto‐D‐gluconic acid, 2,5‐diketo‐D‐gluconic acid, L‐ascorbic acid (Vitamin C) and koji acid.Some of these products are already produced on industrial scale, others show interesting potential to be used as

ISSN:0038-9056    

DOI:10.1002/star.19900420905

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractEffects of cyclodextrins on germinating barley seeds and on the growth of micropropagated strawberry plants were investigated. Treatment of barley seeds with α‐ or β‐cyclodextrins resulted in a similar delay of germination as reported earlier [1]. The delay of germination occurred with agarose‐immobilized as well as with free cyclodextrins. Since penetration of immobilized cyclodextrins into the seeds is limited, it was concluded that the delay resulted from complexation of growth factors. Soluble cyclodextrins caused a growth retardation with micropropagated strawberry plants and certain morphological changes resembling the ones observed when the action of auxins is enhanced in the respect to cyt

ISSN:0038-9056    

DOI:10.1002/star.19900420906

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe chimeric CGTase, which was constructed genetically with two β‐CD forming type enzyme genes of different species of alkalophilic Bacillus, was characterized by comparing with the actions of parent enzymes. The final composition of CDs in the reaction digest from starch by the chimeric enzyme, especially in the yield of α‐CD, was different from those by parent enzymes, and total yields of CDs by these enzymes were almost the same. The chimeric enzyme catalyzed the formation of β‐CD as a major action from starch, the rapid synthesis of α‐CD from other CDs and maltooligosaccharides and the slow degradation and interconversion of α‐CD to others. From these results, the role of second and third segments in the enzyme molecules

ISSN:0038-9056    

DOI:10.1002/star.19900420907

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA simple method ofA. nigerC58‐IIIcell immobilization is described. This strain produces extracellular glucoamylase. According to the proposed methodA. nigerspores were first immobilized by adsorption in sintered glass Rasching rings (RR) or pumice stones (PS). Growing out from spores,A. nigercells produced extracellular glucoamylase. This technique facilitates the culture growth in a filamentous spongy structure of the supports with a continuous accumulation of biomass. After every 24 h it was possible to obtain culture liquid rich in glucoamylase. This procedure can be repeated 30 times using the same sample of immobilizedA. nigerculture without any loss of glucoamylase activity in the liquid medium. In a 96 h period immobilizedA. nigercells produced 300 units × ml−1whereas a shake culture of this fungus produced only 186 units ×

ISSN:0038-9056    

DOI:10.1002/star.19900420908

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900420909

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900420910

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900420911

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY