摘要:

AbstractEach starch is unique. Recognition of this fact provides opportunities for new products, while nonrecognition may delay progress in understanding the specific natures of granules. Each starch needs to be modified to increase its usefulness and value, but it is unlikely that any new derivatives or degrees of substitution will be allowed. Four possibilities for new modified‐starch products other than physically modified products, are offerred: (1) control of reaction sites within granules, (2) control of reaction sites on molecules, (3) new commercial starch sources, (4) biological modification of existing, commercial, base starches. Because means of accomplishing the former two are not now available, the latter two hold the greatest promise at this tim

ISSN:0038-9056    

DOI:10.1002/star.19970490402

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractFonio (Digitaria exilisStapf) starch was isolated from the seeds of two varieties denominated Hothia and Koulli and its physicochemical properties were compared with those of commercial wheat starch. Fonio starch granules seen under a SEM had polygonal shapes and small size (about 8μm). Amylose content of Hothia (22.6%) was significantly lower than that of Koulli and wheat (26.1% and 25.0%, respectively). there was not any significant difference in lipid content of fonio starches (2.8% and 2.9%), whereas significant differences were observed in their water binding capacity (88% and 80%). Protein and ash were also determined. The swelling power and solubility of wheat and fonio starches within the 50°C‐90°C temperature range were also studied. Brabender amylograms of 5% fonio starch slurries showed similarly shaped, single‐step curves. However, the two fonio varieties reached quite different viscosity values during the heating and cooling

ISSN:0038-9056    

DOI:10.1002/star.19970490403

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractUnisolated rice starch was used for hydroxypropylation and calcium complexation. Viscosity was measured at different starch concentrations, temperatures, and shear rates. The viscosity decreased with increase of calcium concentrations and shear rates. Temperature, starch concentrations and levels of Molar Substitution (MS) enhanced the viscosity. Hysteresis behaviour was markedly influenced by levels of calcium and MS. Higher viscosity was observed in hydroxypropyl starch. It is assumed that starch molecules exist in an expanded and/or extended forms which may result in higher viscosity. Calcium treated starch shows lower viscosity. Calcium ions possibly squeezed the starch molecules into a tighter configuration and/or calcium may compete with starch for water causing the limitation of water thus resulting in reduction of viscosity. Higher viscosity was observed at higher temperatures. Higher temperature cause the starch granules swelling thus produce higher frictional forces responsible for higher viscosity.

ISSN:0038-9056    

DOI:10.1002/star.19970490404

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractLarge (A) and small (B) granules from wheat starch were subjected to α‐amylolysis. The B granules were solubilised faster than the A granules. The solubilised dextrins we separated from the enzyme before a secondary hydrolysis of the products occurred and then characterized. The size‐distribution of the hydrolysis products ranged between a degree of polymerization of 2–500. The dextrins solubilised from the B granules contained somewhat more linear fragments and had smaller average chain length than the corresponding dextrins from the A granules. The composition of the residues of the A granules remained practically unchanged, whereas the B granules contained somewhat less amylose. Both granule types possessed extensive fragmentation of some granules, whereas other granules were virtually untouched by the

ISSN:0038-9056    

DOI:10.1002/star.19970490405

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractAn oligo‐1,6‐glucosidase (dextrin 6‐α‐D‐glucanhydrolase, EC 3.2.1.10) of the caldoactive thermophileBacillus caldotenaxKP 1213 (YT‐G, DSM406) was purified to homogeneity. Its relative molecular weight,Stokesradius, sedimentation coefficient at 20°C in water, molar absorption coefficient at 280nm and pH 6.8, and isoelectric point were estimated to be 64,000, 3.3nm, 4.8S, 122,000M−1cm−1, and 4.9, respectively. The enzyme N‐terminal sequence of twenty residues was determined to be Met1‐Glu‐Trp‐Ala‐Trp‐Lys‐Glu‐Ala‐Val‐Val‐Tyr‐Gln‐Ile‐Tyr‐Pro‐Arg‐Met‐Phe‐Tyr20. The enzyme shared its antigenic groups in part with the homologue fromBacillus thermoglucosidasiusKP1006 (DSM2542, obligate thermophile). TheB. caldotenaxenzyme was most active at 70°C and at pH 6.0–6.8. The best substrate for the enzyme was isomaltotriose of naturally‐occurring oligo‐ and polysaccharides tested. The enzyme half‐life at pH 6.8 was 10min at 75°C. The enzyme (Pro, 5.93mol%) fairly matched with a positive relationship between the thermostability of its six bacillary counterparts and their proline mol% contents. This relationship has been found to hold for sixteen bacterial enzymes from other four different groups (

ISSN:0038-9056    

DOI:10.1002/star.19970490406

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractOligosaccharide mixtures were obtained by enzymatic degradation of tamarind xyloglucan from the seeds ofTamarindus indicaby commercialAspergillus nigerendo‐(1→4)‐β‐D‐glucanase, and their composition analyzed by HPAE‐PAD liquid chromatography revealing two major groups of oligosaccharides. The first group contained oligomers of DP 7, 8 and 9, while the second group consisted of a large variety of oligomers of DP 12 to 18. After purification by SEC and HPLC in semi‐preparative scale, single oligomers were characterized by glycosyl‐residue composition, glycosyl‐linkage analysis and plasma desorption mass spectrometry. Beside β‐D‐Glucosyl, β‐D‐galactosyl and α‐D‐xylosyl units, some higher oligomers contained β‐D‐galactosyl‐(1→5)‐α‐L‐arabinosyl units, linked to O‐6 in the glucosyl units of the (1→4)‐β‐D‐glucan backbone. OtherL‐arabinosyl residues were located in terminal positions of α‐D‐xylosyl side chains. The variety of isolated oligomers reflected a complicated random distribution of side chains in tamarind xyloglucan. Based on the characteristics of the oligomer

ISSN:0038-9056    

DOI:10.1002/star.19970490407

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractEs wurden Synthesen zur Derivatisierung von β‐Cyclodextrin durchgeführt mit dem Ziel, den Derivaten bzw. ihren Gemischen partiell hydrophobe Eigenschaften zu verleihen. Aufgrund solcher Eigenschaften ist zu erwarten, daß sie nach Methoden der Dispersionsfärbung auf Polyestergewebe zu verankern sind und daß sie weiterhin aufgrund der unsubstituierten OH‐Gruppen des Cyclodextrin‐Torus wasserfreundliche als auch durch den Hohlraum des Cyclodextrinderivats komplexierende Eigenschaften behalten und somit der Gewebeoberfläche vermitteln. Die erfolgreiche Verankerung am Gewebe sowie die Nachweismethoden (Fluoreszenzeigenschaften komplexierter Farbstoffe, Jodeinlagerung, FT‐IR‐Spektroskopie) wer

ISSN:0038-9056    

DOI:10.1002/star.19970490408

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970490409

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970490410

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970490411

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY