摘要:

AbstractMolecular change of potato starch granule by ball‐mill treatment was investigated. Starch granule still retained its whole figure after 320h, treatment, but its surface changed extremely rough. Water absorption activity extremely increased by 10h treatment. Amylase susceptivity of starch increased according to treatment time. X‐ray diffraction pattern lost its peak and enthalpy on DSC decreased 70% after 20h treatment. Iodine color reaction value decreased 30% and λ max shifted hypso‐chromic 15nm in the both cases of debranched and non‐debranched samples after 20h treatment, and this indicates amylose was also degraded by the treatment. However, the peak of amylose decreased 10% and the peak of amylopectin decreased 10% on each GPC of branched and non‐debranched samples after 20h treatment. GPC (Toyopearl HW‐65) of 320h treated sample shows only one peak, but its debranched sample shows similar pattern to that of non‐treated sample on HPAEC.13C‐solid state NMR spectra suggest that total disruption frequency is fairly low after lon

ISSN:0038-9056    

DOI:10.1002/star.19970491102

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThis paper describes the comparison of potato amylose‐free starches obtained by two different approaches: mutation induction of the gene encoding the key‐enzyme in amylose biosynthesis Granule Bound Starch Synthase (GBSS) and antisense inhibition of the expression of GBSS, with that of normal amylose containing potato starch. One of the most prominent differences between the amylose‐free and amylose‐containing starches was their phenotype after staining with iodine. The amylose‐free starch obtained via mutation induction stained completely red whereas the amylose‐free starch obtained by the antisense approach always had a very small dark‐blue staining core in a further entirely red staining granule. Amylose‐containing starch stained blue with iodine. Differences were also observed with regard to the absence of GBSS protein and activity in the amylose‐free potatoes. Furthermore the lambda max and the blue value of the amylose‐free starches was markedly different as would be expected since they almost completely lacked (<0.1%) amylose in both types of amylose‐free starches. Determination of a number of different chemical parameters including particle size distribution, ion content, as well as phosphate levels of the starch indicated that these were not different in the amylose‐free containing starches as compared to the normal amylose containing starches. The absence of amylose resulted in improved gel stability and paste clarity of gels even after prolonged durations at 5°C

ISSN:0038-9056    

DOI:10.1002/star.19970491103

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractIn this paper some physico‐chemical characteristics of amylose‐free potato starch are described and compared to those from amylose containing potato starches. The availability of these high‐amylopection or amylose‐free starches has opened up new possibilities to assess the relationship between structural characteristics and physico‐chemical properties of potato starch. At the same time it should be possible to determine more precisely the role of the amylose in the starch on several properties and characteristics. In all different analyses it was clear that amylose‐free starch displayed unique properties. Not only was the response to heating much faster; it also occurred at much higher temperatures as demonstrated by viscographs, differential scanning calorimetry and swelling experiments. Rheological analyses demonstrated that gels formed from amylose‐free starch were less rigid, smoother and shorter. The breaking of amylose‐free gels furthermore required much less strength than that of amylose‐containing gels. This aspect was also evident when threads were made from both starches; amylose‐free threads were much shorter before breaking than threads made from amylos

ISSN:0038-9056    

DOI:10.1002/star.19970491104

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractA rapid enzymatic method for simultaneous determination of digestible and resistant starch in standards and foods is presented. The procedure for the determination of the digestible starch fraction was optimized. The main steps of this were: the removal of digestible starch, the hydrolysis of products and quantification of digestible starch as released glucose. Stomach and intestine physiological conditions (pH, transit time) are simulated approximately. The method was evaluated by the analysis of the starch content in various standards and raw foods. The method has showed a high precision and a good accuracy. Some variables, such as employment of sodium azide, incubation time of α‐amylase and amyloglucosidase amount, which might affect the levels of digestible and resistant starch are also evaluated and discuss

ISSN:0038-9056    

DOI:10.1002/star.19970491105

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractDegradation of cationic starches and subsequent permethylation andHofmann‐elimination of the methyl‐glucosides yields the corresponding enolether derivatives, which can be analyzed by GLC and GLC‐MS. The relative ratio of 2‐, 3‐ and 6‐substitution in the anhydroglucose unit as well as of un‐, mono‐, di‐ and trisubstitution in the anhydroglucose unit as well as of un‐, mono‐, di‐ and trisubstituted monomers can be determined. The experimental results are compared with the data calculated by means of a kinetic model. Only slight deviations from a random distribution in the anhydroglucose unit are observed and discussed. Enzymatic degradation of the cationic starch ethers and measurement of the liberated glucose should give indication to the distribution

ISSN:0038-9056    

DOI:10.1002/star.19970491106

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractNative corn starch was cross linked with phosphorus oxychloride (POCl3) before and after cationization to DS 0.04 in an aqueous ethanolic‐alkaline solvent with no adverse effects on the cationization reaction rate. Cross linking at six levels of POCl3(7.5–120μ1/50g starch) demonstrated that the gelatinization temperatures of cationic starch increased but enthalpies of gelatinization (ΔH) decreased in proportion to the amount of added POCl3. Amylograph viscosities increased with level of POCl3up to a maximum of 45μl POCl3and then decreased markedly at higher concentrations of POCl3. At 30–45μl POCl3, the amylograph viscosities of cationic corn starch increased very rapidly and remained uniformly high throughout the rest of the heating and cooling cycle. At this level of cross linking and cationization, the modified starch could be used industrially as an adhesive or in paper manufacture at more dilute concentrations and with less energy input for mixing the slurry than would be required for cationic starches which exhibit high peak viscosities but negative setbacks o

ISSN:0038-9056    

DOI:10.1002/star.19970491107

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractSome kinetic characteristics and hydrolytic action patterns on various β‐D‐galactosyl‐maltooligosaccharides (Gal‐Gn), ranging in size from D.P. (degree of polymerization) 5 to 8, of an exo‐maltotetraose‐forming amylase ofPseudomonas stutzeri(G4‐amylase) were examined to produce a fewp‐nitrophenyl β‐D‐galactosyl‐α‐maltooligosaccharides (Gal‐GnP, n = 4,5).The relative hydrolytic reaction rates for larger Gal‐Gn by the enzyme were larger than those for smaller saccharides tough the values for unmodified linear maltooligosachharides were almost same.Michaelisconstants (Km) for hydrolysis of Gal‐G4, Gal‐G5, Gal‐G6 and Gal‐G7 by the enzyme were 1.3, 1.9, 1.3 and 1.3mM, and apparent molecular activities (ko) for these saccharides were 5.9, 38, 91 and 126s−1, respectively. The values ofko/Km for them were remarkably smaller than those for unmodified linear maltooligosaccharides.The G4‐amylase cleaved 2 points of the α‐1,4‐glucosidic linkage in β‐1,4‐Gal‐G4 to give β‐1,4‐Gal‐G2 and ‐Gal‐G3 in the molar ratio of 3:1, whereas the enzyme attacked 3 points of the linkage in β‐1,4‐Gal‐G5, ‐Gal‐G6 and ‐Gal‐G7 to form β‐1,4‐Gal‐G2,‐Gal‐G3 and Gal‐G4 in the molar ratios of 2:5:1, 1:3:6 and 1:3:6, in the early stage of the reaction, respectively. On the other hand, the enzyme showed no action on β‐1,6‐Gal‐G4 and formed β‐1,6‐Gal‐G4 solely from β‐1,6‐Gal‐G5, and β‐1,6‐Gal‐G4 and ‐Gal‐G5 were from β‐1,6‐Gal‐G6 and ‐Gal‐G7 in the ratios of 8:1 and 2:1, respectively.The enzyme also catalyzed the transfer action to produce Gal‐G3P, Gal‐G4P and Gal‐G5P, of which the formation ratio was coincided well with the hydrolytic action pattern on each Gal‐Gn, from Gal‐Gn tested as a donor andp‐nitrophenyl α‐glucoside (GP) as an acceptor in an aqueous solution containing 40%

ISSN:0038-9056    

DOI:10.1002/star.19970491108

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491109

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491110

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491111

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY