摘要:

AbstractCanaryseed starches from three locations were isolated by an alkali steeping process and evaluated for their chemical, pasting and structural properties by amylograph, scanning electron microscope (SEM), differential scanning calorimeter, X‐ray diffractometer and image analysis, in comparison with isolated wheat starch. The average yield of canaryseed starch was 50 ± 2.9g starch per 100g of groat with a mean extraction efficiency of 77%. The starch isolates contained from 93 to 97% starch with amylose contents ranging from 16 to 22%. Canaryseed starch was uniform in appearance, being small polygonal granules having an average diameter of 2.0 μm. The granules were stable when subjected to shear and heat effects as indicated by visco/amylograph response and SEM‐photomicrographs. The transition temperatures (peak and conclusion) and enthalpy of gelatinization of canaryseed starch were higher than those of wheat starch. Canaryseed starch showed major peaks around d‐spacings of 5.9, 5.2, 4.8 and 3.8 Å similar to wheat starch which are characteristics of an A‐type starch. Canaryseed starch was also more susceptible to α‐amylase hydrolysis and more soluble in dimethyl sulfoxide as compared with wheat starch. Based on its ease of extraction and functional properties, canaryseed starch could have potential for food and

ISSN:0038-9056    

DOI:10.1002/star.19970491202

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractA factorial experiment (4 × 2 × 2) was carried out to study the effect of a fiber degrading enzyme complex on starch yield, SO2steeping time and starch properties of normal red sorghum (RS), heterowaxy (WHWx) and waxy (WWx) white sorghums compared to regular yellow maize (YM). Starch yields and total starch recovery for the sorghums ranged from 53–64% and 70–85%, respectively. Sorghum starch recovery values were significantly lower (p<0.05) than maize (66% starch yield and 88% recovery). However, the WWx yielded more starch with lower protein and ash contents (P<0.05) than the RS and WHWx sorghums. In the RS, the fiber degrading enzymes reduced steep time while owing the same starch recovery. The WWx starch required lower temperature to initiate gelatinization and had higher peak viscosities and lower retrogradation than the other starches. The WHWx starch had intermediate viscoamylograph properties between the regular and waxy sta

ISSN:0038-9056    

DOI:10.1002/star.19970491203

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe work of Work Group 3, of the International Standards Organization Technical Committee 93 (ISO/TC 93/WG3), concerning the determination of functional groups in starch derivatives, has been progressed. The Netherlands Normalisatie Instituut (NNI) is the secretariat and Part I of this paper outlined the total work programme and reported the finalised work on acetyl and carboxyl functions.Following modifications, the available methodology for the adipyl function was improved, and has been validated. The methodology for the determination of the carboxymethyl function by titration of the carboxyl group, has also been refined and validated by collaborative testing. Draft International Standards have been made of these two methods so that they can be voted on by members of ISO and the European Committee for Standardization (CEN) in a parallel process.Work on the hydroxypropyl function has not yet come to a successful conclusion. A colorimetric method showed poor reproducibility, due probably to its empirical nature; little support was found for gas chromatographic methods. However, the use of proton NMR might yield a satisfactory means. While all members of the Work Group are not equipped with the required instrument, a preliminary study will be done with the help of other laboratories.

ISSN:0038-9056    

DOI:10.1002/star.19970491204

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

Abstract13C NMR signal assignments were achieved for amylose and amylopectin triacetates and a series of partially acetylated, acid degraded amylopectin derivatives. Using the relative intensities of several of these signals for the latter materials the following could be deduced. First, within the molar substitution range of 0.47 and 0.72 the acetylation of partially degraded amylopectins takes place randomly distributed at all glucan moieties of the polysaccharide. Second, the probabilities of substitutions of hydroxyl groups in positions 2, 3, and 6 of a discrete glucan moiety are equivalent.

ISSN:0038-9056    

DOI:10.1002/star.19970491205

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractThe hydrolysis of acetylated starches with different subsitutions degrees was conducted with an enzyme active at 90°C. The extent of degradation was evaluated by colorimetric and chromatographic methods.With slightly acetylated starches, 100% of the substrate was fragmented and the main product obtained was maltose. The classification of these different substrates according to their percentage of biofragmentation was the same with the two methods.With highly acetylated starches, the degradation was lower and the decomposition products are mainly maltose, maltotriose and pentaose. The classification of the different substrates was also the same with the two methods. Moreover, the values of the kinetic parameters confirmed these classifications

ISSN:0038-9056    

DOI:10.1002/star.19970491206

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractHighly carboxymethylated potato starches (HCMS) with various degrees of substitution ranging 0.48‐0.60 were produced and their physicochemical and functional properties were examined. The degree of substitution could be increased by prior treatment of starch with acid, although the longer the treatment the percentage of low molecular weight starches increased slightly. HCMS showed a pseudoplastic flow having the power law index less than 1.0. HCMS swelled readily in cold water (15°C), formed a clear solution, and were resistant to retrogradation. The viscosity of HCMS prepared without or with 15min acid treatment was similar or higher than that of native starch at the beginning of amylography, however, it decreased gradually from the rest of the stage. HCMS prepared with longer acid treatments exhibited extremely low viscosity throughout the test period. The digestibility of HCMS by α‐amylase decreased greatly in proportional to the degree of substitution. Scanning electron microscopic observation revealed fine fissures and grooves on the surface of HCMS granules, suggesting part of amylose has been leached by the acid trea

ISSN:0038-9056    

DOI:10.1002/star.19970491207

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

摘要:

AbstractSodium hydroxide and sodium salts of acetate, nitrate and sulfate were chosen as pushing agents for maltodextrin analysis by high‐performance anion‐exchange chromatography with pulsed amperometric detection (HPAEC‐PAD). Different concentrations of sodium hydroxide solution, 100 mM to 500 mM, were used for direct detection of maltodextrins on a set of gold working and saturated calomel reference electrodes. Chromatographic capacity factors, k′, of maltodextrins increased as molecular size increased. Sodium hydroxide alone was not adequate for an optimal maltodextrin separation. Sodium salts of acetate, nitrate, and sulfate were tested as pushing agents.The salts were compatible with the system, increased the separation selectivity and enhanced the detector response of PAD. The ability of pushing agents to decrease k′ followed the order of sulfate>nitrate>acetate>hydroxide. After being eluted with pushing agents, the column regeneration time of CarboPac PA1 was 180, 240 and 360 min for the acetate, nitrate, and sulfate salts, respectively. An alternate process to shorten the regeneration time for maltodextrin separation was demonstrated. Sodium azide, as a preservative, did not affect the separation and quantification of the analysis. Sodium nitrate was the best pushing agent for the homologous maltodextrin s

ISSN:0038-9056    

DOI:10.1002/star.19970491208

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491209

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491210

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19970491211

出版商:WILEY‐VCH Verlag GmbH    

年代:1997

数据来源: WILEY