摘要:

AbstractA diluted solution of Bacillus amyloliquefaciens α‐amylase was pumped through a layer of smooth pea starch granules in a column and further into a bed of ion‐exchanger that retained the enzyme but not the solubilised dextrins. The design of the experiment prevented a secondary hydrolysis of the originally solubilised dextrins. The granules were quite resistant to hydrolysis and collected dextrins from the initial stages of the solubilisation of both large and small granules had d.p. (degree of polymerization) 2–100. Large granules that were treated with a more concentrated enzyme solution in a test‐tube, were solubilised up to 7%. The granular residues contained increased amounts of dextrins in the d.p.‐range 50–300. Scanning electron microscopy revealed an extensive fragmentation of the granules and the enzyme had preferentially attacked the starch in layers between the

ISSN:0038-9056    

DOI:10.1002/star.19930450702

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractA new starch‐based fat replacer called STELLAR, is prepared by controlled acid hydrolysis of corn starch. Fat‐like properties arise from the particle gel structure developed on shearing the insoluble starch product in water to produce a firm, deformable creme. The new fat replacer has an average molecular weight of less than 20,000 and is composed of crystallites comprised of double helical structures. Based on actual particle size analyses and calculations made on surface area data, it is concluded that the creme is comprised of loosely aggregated submicron size particles. This is corroborated by transmission electron microscopy results. Oxygen 17NMR measurements demonstrate the importance of water immobilization during creme formation. The functional properties of the new starch based fat replacer are discussed in relation to its struct

ISSN:0038-9056    

DOI:10.1002/star.19930450703

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractA novel type of reactor for the chemical derivatization of starch pastes is presented. The design is based on the application of static mixers. The reactor shows excellent plug flow behaviour with a Peclet number of about 100. The viscosity behaviour of concentrated starch pastes in the static mixer reactor can be described by:ηapp = Ke[B mstarch+c/T‐DW+(n‐l)Inγ] where: K = 3.063.10−4Pa‐s., B = 12.03, C = 4.134.103 1/K., D = 2.83.10−23kg dry starch/kJ and n = 0.494. mstarchis the mass fraction dry starch in the paste.The reactor was used for the production of hydroxypropyl starch with a molar substitution (MS) of up to 0.5. Propylene oxide conversions of 90% were reached within 9 min of reaction time which compares favourable with conventional production processes. The reactor was modelled as a non‐isotherm plug flow reactor. Experimental results on propylene oxide conversion and MS of the derived starch are in good agreement with model calculations.Papp = Ke [Bm starch+ c/T‐DW+(n‐l)Inγ]wobei: K = 3,063. 10‐−4pa.s., B=12,03. C= 4,134, C=4,134, 1‐3I/K., D = 2.83.10−2kg trockene Stärke/kJ, und n = 0,494. mstarchist die Massenfraktion t

ISSN:0038-9056    

DOI:10.1002/star.19930450704

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

Abstractα‐Amylases are known to be multidomain proteins, i.e., the molecules consist of several folding units. Each α‐amylase is believed, however, to have a catalytic domain consisting, of a barrel of eight parallel α‐strands surrounded by eight α‐strands. with an extra helix inserted after the sixth γ‐strands. The α‐strands and helices alternate along the polypeptide chain and are linked together by irregular loops. Amino acid residues situated on the loops joining the C‐terminal end of each α‐strand to the N‐terminal end of the following helix make up the active site of the enzymes. A similar structure has been found in cyclodextrin glucanotransfcrases and it is now believed that such a (α/α)8‐barrel also constitutes the catalytic domain of enzymes active on α‐1.6‐glucosidic bonds, and of enzymes with dual specificity for both α‐1.4‐ and α‐1.6‐ bonds.Knowledge of the three‐dimensional structure of α‐amylases and cyclodextrin glucanotransferase has made possible identification of structural features important for enzymic activity and specificity. By analogy, some general conclusions are reached concerning pullulanase, isoamylase. oligo‐1,6

ISSN:0038-9056    

DOI:10.1002/star.19930450705

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractRaw sago starch digesting amylase was obtained from Penicillium brunneum No. 24. with strong ability to digest sago starch granules. The crude enzyme from this strain contains CMC‐ase and avicelase. The specific activity of the enzyme did not increase proportionally with purification. We tried combination of our purified enzyme with other hydrolytic enzymes as a means of improving the hydrolysis of sago starch granules.Addition of cellulase at the initial stage of the hydrolyzation process resulted in an increase in the ability of raw starch digesting amylase to digest sago starch granules. Adding 10 unit/g starch of cellulase. followed of our purified raw starch digesting amylase in small portion at various time intervals was found effective in the hydrolysis of untreated sago starch granules. The treatment resulted in a convertion rate of untreated sago starch granules to glucose near to complete after 120h enzymes reaction, and was also effective in reducing the reaction time of hydrolysis of treated sago starch granules. This process showed that mainly glucose was produce

ISSN:0038-9056    

DOI:10.1002/star.19930450706

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractTreatment of the sago starch granules before incubation with the enzyme by heating to below gelatinization temperature at low pH condition was effective in improving the hydrolysis. Glucose could be produced from treated (at 60C. pH 2.0) sago starch granules using the raw sago starch digesting amylase from our strain. Alcohol fermentation from the treated sago starch granules using the raw sago starch digesting amylase from Penicillium brunneum and a strain of yeast, Saccharomyces cerevisiae No. 33 could produce ethanol under incubation conditions of 35C, pH 4.8. Addition of yeast and an extra half dose of enzyme after 24 h enzyme reaction was sufficient to continue starch hydrolysis during fermentation. This condition resulted in a conversion of sago starch to ethanol at a rate of about 44% in 72 h culture time.

ISSN:0038-9056    

DOI:10.1002/star.19930450707

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractGuar gum was cyanoethylated under a variety of conditions. It is shown that the extent of reaction increases by increasing the acrylo‐concentration nitrile and decreases by increasing the reaction temperature. Cyanoethyl guaran pastes are characterized by non‐Newtonian pseudoplastic behaviour and may be described by the power low T = kDnin which the rheological parameters k and n depend mainly on the type of the derivatives. The apparent viscosity of these derivatives depends on its nitrogen content as well as the rate of sh

ISSN:0038-9056    

DOI:10.1002/star.19930450708

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19930450709

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19930450710

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19930450711

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY