摘要:

AbstractMung bean starch is used as a high‐grade raw material for noodle production in the food industry. Until now the applied separation techniques are often less efficient. Therefore, investigations were carried out on the laboratory scale to give first informations about the development of new separation techniques. The raw materials were flour and whole kernels. In both cases it was possible to produce a pure starch with a protein content less than 0.2% in dry matter. Physical and chemical investigations of the isolated starch pointed to the qualification of mung bean starch in different application fields, especially in view of the high viscosit

ISSN:0038-9056    

DOI:10.1002/star.19900420102

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe lysine rich high protein seeds ofA. paniculatas(Rajgeera) are reported to contain 50–60% of waxy starch, concentrated in the endosperm. However its food related properties are comparatively unknown. In the present work, paste viscosity, paste clarity, freeze‐thaw stability and effect of shear on the viscosity ofA. paniculatasstarch paste have been studied and compared to corn starch. Also included are the stability of Rajgeera starch paste under pressure cooking (30 min, 15 lb pressure) and acidic conditions (pH 6.98—1.76). Rajgeera starch was found to have a higher paste viscosity, lower paste clarity and high freeze‐thaw stability than corn starch. Both Rajgeera and corn starch underwent thinning on being subjected to mechanical shear. Rajgeera starch withstood pressure cooking conditions admirably, but was found to be sensitive to acidic con

ISSN:0038-9056    

DOI:10.1002/star.19900420103

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractTheEwersmethod for starch determination is currently the Official EEC method for measurement of starch purity. In this communication we demonstrate that the use of trifluroacetic acid for solubilisation of starch prior to polarimetric measurements is preferred over the use of mineral acids since the degree of hydrolytic degradation observed with this reagent was minimal compared to mineral acids, thereby giving improved starch purity values. Of particular concern we demonstrate that theEwersmethod is non‐specific in that the addition of an epichlorohydrin cross‐linked dextran as an adulterant enhances the value of starch purity obtained. TheEwersmethod however was able to detect agarose and carboxymethyl cellulose added to starch as adulterants.It is concluded that theEwersmethod is not an acceptably satisfactory method for starch purity measurement on which to base quality control or eligibility for rebate and refund sche

ISSN:0038-9056    

DOI:10.1002/star.19900420104

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe processing of cassava (Manihot utilissimaPohl) root IITA variety TMS 50395 into starch by varying the steeping period and the effect of these processing methods on the suitability of cassava starch produced for adhesive formulation were investigated. Out of the three processing methods, the one without steeping gave the best starch for adhesive production in terms of the physico‐chemical properties such as swelling power. pH, cooking properties, yield, ease of extraction and cost of starch processing. 20% Potassium hydroxide were found to produce the best adhesive product based on the total solids content, pH, colour and applicabilit

ISSN:0038-9056    

DOI:10.1002/star.19900420105

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractCorn starch was phosphated on a Brabender single screw extruder at different extrusion temperatures, sodium tripolyphosphate (STP) concentration and pH of the medium. The highest degree of substitution (DS) was obtained at extrusion temperature of 200°C, STP concentration equal or superior of 1.4g/100mL of water and pH of 8.5. The DS was related to paste clarity while the extrusion process, to the water absorption index and water solubility index, independently of the DS

ISSN:0038-9056    

DOI:10.1002/star.19900420106

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractStarch of different molecular sizes brought about by oxidation of maize and rice starches were cyanoethylated under identical conditions. The degree of cyanoethylation, expressed as % N, was found to depend mainly on the molecular size of starch irrespective of its kind. As the molecular size decreases the degree of cyanoethylation increases. Cyanoethyl starches are water soluble and can be precipitated by ethanol. It was also found that the rheological properties are determined by the nitrogen content of cyanoethyl starch. When the latter acquires low nitrogen content, it exhibits non‐Newtonianpseudoplastic behaviour. On the other hand, cyanoethyl starches with higher nitrogen content are characterized by non‐Newtonianthixotropic. At constant rate of shear, the apparent viscosity of cyanoethyl starches is directly related to its molecular size. Storing of pastes prepared from these cyanoethyl starches for 7 d exerts considerable influence on rheological properties and apparent viscosity of these derivati

ISSN:0038-9056    

DOI:10.1002/star.19900420107

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractStreptomyces violaceonigerglucose isomerase (GI) was originally developed in 1973 when expectations about the future of HFCS in Europe were great. Improvement of the original strain CBS 409—73 obliged to consider the possible utilizations of genetic engineering as the best possible way for obtaining hyperproduction of the enzyme. The structure gene of GI was cloned and transferred in an integrating plasmid PUT 220 derived from pIJ 702. The sequence of the gene was determined and compared to the aminoacid sequence of the purified glucose isomerase. Crystallization of the enzyme was achieved and its 3‐D structure established;S. volaceonigerGI is normally existing as a tetramer with 4 identical sub‐units of 388AA each. The monomer includes a (alpha‐beta) 8 barrel sub‐structure and a large hydrophobic loop involved in the formation of dimers. Simultaneously, structural analysis ofS. olivochromogenesGI revealed a great similitude withS. violaceonigerGI, though the former could exist as a dimer.In view of this situation and considering that because of a high level of homology, both enzymes presented significant differences in their functional properties, hybrid molecules were constructed and site directed mutagenesis utilized to create new GI species with modified p

ISSN:0038-9056    

DOI:10.1002/star.19900420108

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractA bacterium,Arthrobacter globiformisS64—1, produced an inulinase in the culture broth. The enzyme was purified 442‐fold by DEAE‐Toyopearl chromatographies. It showed maximal activity at 40°C and pH 6.5. The enzyme activity was inhibited strongly by Hg2+, Fe3+, Cu2+and EDTA. The molecular weight of the enzyme was estimated to be 100,000 by SDS‐PAGE. The isoelctric point of the enzyme was estimated to be 4.8 by isoelectric focusing on a polyacrylamide gel. The enzyme degraded inulin through an exo‐typ

ISSN:0038-9056    

DOI:10.1002/star.19900420109

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractWhereas its renewable source, vegetal carbon will trend more and more to be considered as a starting raw material for organic synthesis. Although cellulose is proportional the first in volume, starch shows the most industrial development to versatile polymers and molecules due to chemical and biochemical conversions. However, chemistry of saccharides and polyols is made tedious because of the polyfunctionality. This last point leads to a specific reactional strategy built up with protection of reactional groups. Time‐consuming and uneconomical steps have sometimes dissuaded industrial researchers from developing new molecules. So, development of new synthetic routs and catalysts with specific separation tools will open the door to a new generation of products comming from sucrochemistry, with better yields and improved selectivity. In order to illustrate this new way, acetalisation of sorbitol with benzaldehyde has been chosen. An inverse phase transfer catalysis (PTC) is used and comparison with a traditional catalysis is made. After reviewing different operational factors, emphasize is put on the highest selectivity obtained with a PT

ISSN:0038-9056    

DOI:10.1002/star.19900420110

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900420111

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY