摘要:

AbstractStarch from six clonal selections ofDioscorea rotundatawas isolated by standard procedure. The yield was between 20–24%. Various properties of these starches were compared. Granule size, 2% viscosity, peak viscosity, clarity, sol stability, total and soluble amylose contents were studied and only small variations were observed in the properties except paste viscosities among the clonal selections. The phosphorus content ofDioscoreastarch was found to be three times as much as cassava starch, but low compared to potato starch. The higher gel strength ofD. rotundatastarch paste compared to cassava gel may be attributed to the phosphate linkages among the starch molecules in the granule

ISSN:0038-9056    

DOI:10.1002/star.19890410302

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of fermentation and added NaCl on aqueous dispersions of black gram flour were studied. After fermentation the apparent viscosities of cold pastes increased significantly over that of native flour dispersions (NFD). Addition of NaCl caused considerable decrease in apparent viscosities of NFD but only marginal decrease in fermented flour dispersions (FFD). Studies on rheological constants showed that changes brought about in these by fermentation were greater than that exerted by adding NaCl. Brabender viscography indicated that peak viscosity (PV) decreased by both NaCl and fermentation. FFD with salt showed 15% increase in PV over that without salt. FFD with or without NaCl showed greater breakdown (BV) and set back (SV) viscosities, but the values were lower in comparison to NFD.Starch was isolated in 33–35% yield from native and fermented batters. Apparent viscosity in 1M KOH showed increase due to fermentation. Brabender viscography indicated a GT of ∽81°C for both starches. The PV of fermented starch increased by 13%, BV by 15% and SV by 30% over that of native. Intrinsic viscosity of starch increased considerably while solubility and swelling power increased only marginally after fermenta

ISSN:0038-9056    

DOI:10.1002/star.19890410303

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractGelatinization temperatures of starch and hydroxyethyl starch was determined using Differential Scanning Calorimetry (DSC), hot stage microscopy and viscography. The gelatinization temperature based on peak temperature of DSC is incorrect. Viscograph overestimates the gelatinization temperature. Hot stage microscopy based on visual observation gives the correct gelatinization temperature. DSC gives the heat of gelatinization which is helpful in estimating heat requirement during cooking of starch. Hydroxyethylation of starch reduces gelatinization temperature and heat of gelatinization for starch.

ISSN:0038-9056    

DOI:10.1002/star.19890410304

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractRaw and variously parboiled Intan rice (intermediate‐amylose variety) starch was fractionated in Sepharose CL‐2B column into a larger‐molecule (Fr I) and a smaller‐molecule (Fr II) fraction. The amount of Fr I decreased and that of Fr II increased in parboiled as compared to raw rice, the extent of change increasing with increasing severity of processing. The proportion of polysaccharide and “amylose” in Fr I decreased from 70% and 40% of total, respectively, in raw rice to 16% in parboiled rice prepared by 3 kg/cm2gauge steam pressure. Simultaneously, the λmaxof its iodine complex increased from 570 to 588 nm in Fr I and decreased from 635 to 620 nm in Fr II. The change was marginal or low after steaming at ambient pressure or after sand roasting. The data show that thermal degradation of starch must be considered as another contributor, in addition to starch gelatinization and reassociation, to the peculiar properties of pa

ISSN:0038-9056    

DOI:10.1002/star.19890410305

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractChemical modifications in starch following heat treatment at low moisture content was studied in relation to enzymic availability of the starch. The samples, native wheat starch and a soluble starch (according toZulkowsky), were heated with or without addition of levoglucosan (1,6‐anhydro‐β‐D‐glucopyranose), a highly reactive compound proposed to be active in transglycosidation reactions. The modifications induced by heat treatment significantly reduced the digestibility of starchin vitro.The decrease in available starch was not accompanied by any increase in dietary fibre, suggesting that the carbohydrate fragments remaining after enzymic digestion were of low molecular weight.The starch in the heated material was highly fragmented and chemical characterization by1H‐nuclear magnetic resonance spectroscopy and methylation analysis revealed the formation of new non‐starch linkages mainly β‐(1→4) and β‐(1→6). It is probable that the introduction of non‐starch linkages reduces the enzymic access also of several adjacing α‐glucosidic bonds. Thus, it could explain the 7% decrease inin vitroavailability after 4 h hea

ISSN:0038-9056    

DOI:10.1002/star.19890410306

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractViscosity, gelatinization characteristics, storage stability, gelling tendency and thermal reversibility of cooked starch and modified starch paste were studied Solution rate of starch and modified starch films in water, hydrochloric acid and enzyme was evaluated. Hydroxyethyl starch showed lower gelatinization temperature, low viscosity, increased storage stability to temperature, time and thermal reversibility. The reheating of cooked paste deteriorates the properties of starch paste but the adhesive properties of hydroxyethyl starch were not affected. The introduction of hydroxyethyl group into starch significantly improved the dissolution ability of the films.

ISSN:0038-9056    

DOI:10.1002/star.19890410307

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractCationic starch‐g‐polymer latexes stabilize soil particles to water. To extend the study of such utility of starch latexes we prepared starch‐g‐poly(methyl acrylate) (S‐g‐PMA) and cationic starch‐g‐poly(methyl acrylate) (CS‐g‐PMA) latexes by the ceric‐initiation procedure, varying the weight ratio of starch or cationic starch to methyl acrylate from (10 to 1) to (1 to 1) in the preparation step. The percent add‐on (percent synthetic polymer in the graft copolymer) ranged from 0.5% to 41% for S‐g‐PMA, and from 4.6% to 43% for CS‐g‐PMA. Application rates required to obtain stable soil are dictated by the amount of PMA in the graft copolymer. For instance, wet sieve testing showed that 10S‐g‐1PMA and 10CS‐g‐1PMA latexes required dose levels of 0.4 g/100 g soil to fully stabilize the test soils. (6–8)S‐g‐1PMA and (6–8)CS‐g‐1PMA latexes gave full stabilization when applied at 0.1 g or 0.2 g/100 g soil rate. Latexes with highest (24.4%–43%) add‐on stabilized soil fully at an application rate of 0.1 g/100 g soil or less

ISSN:0038-9056    

DOI:10.1002/star.19890410308

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractNIR measurement was carried out for a starch dispersion circulating from a reactor to an NIR flow‐through cell over a wavelength range of from 1000 to 2500 nm in 2 nm increments. Multiple regression analysis between NIR and HPLC shows a good correlation. It is shown that the NIR method can be used to determine glucose quantitatively in real time during enzymatic hydrolysis, and that NIR may be employed for controlling the reaction in a bioreacto

ISSN:0038-9056    

DOI:10.1002/star.19890410309

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThermostableThermus sp.AMD 33 pullulanases (I and II) capable of cleaving α‐1,6‐links in pullulan as well as α‐1,4‐glucosidic linkages in amylose were purified to electrophoretically homogeneous states. Relative molecular masses and pI values were determined as 135,000 (I and II) by SDS‐PAGE and 4.2 (I) and 4.3 (II) by isoelectric focusing, respectively. The pullulanase and α‐amylase activities of the purified enzyme II responded similarly to temperature and pH, with optima at 70°C and pH 5.5–6.0. Both activities were activated by Ca2+and inhibited by Hg2+, Fe3+, NBS, DBS, SDS and urea to almost the same extent. Both activities were also inhibited competitively by CDs. Enzyme II catalyzed the hydrolysis of α‐1,6‐glucosidic linkages in maltosyl‐ and maltotriosyl‐α‐CD as well as that of α‐1,4‐bonds in amylose and related linear malto‐oligosaccarides larger than maltotriose, but exhibited no action o

ISSN:0038-9056    

DOI:10.1002/star.19890410310

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19890410311

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY