摘要:

AbstractThe temperature‐dependent dyeability of oligoglucanes and polyglucanes with I2/KI solution is based on the interaction between iodine and the C‐atoms of glucosidic bonds (VetterandThorn[1, 2]). Only when the helix is compressed, the expansion of the lumen that is necessary for the attachment of iodine bands is achieved as suggested byFreudenberget al. in 1939 [3].The development of colour starts with the maltododecaosis (just over two spirals) within a temperature range of 20 to 25°C adsorbing one pentaiodide and bringing about a pale shade of pink. The rich blue tone is achieved with pure amyloses forming a maximum of about 610 to 620 nm. Unramified polysaccharides which had been synthesised by our team from 30 glucoside residues, still showed a purple colour with a maximum of 510 nm at temperatures from 20 to 25°C. Defined polysaccharides from 40 residues are bluish‐purple (just 7 spirals of a tension‐free helix) with a maximum absorption of about 550 nm. According to our knowledge, the rich blue tone requires at least 50 glucoside residues linked in an unramified chain [1, 2].Amylopectin from potatoes has a maximum of 575 to 580 nm which shifts to 555 to 560 nm after partial break‐down into β‐dextrin by β‐amylase (EC 3.2.1.2) and does a long‐wave re‐shift to 570 nm after splitting off of the side‐chain stumps in the basic structure by pullulanase (EC 3.2.1.41). In the case of maize, the maximum is 535 nm for amylopectin, 520 nm for β‐dextrin, and 555 nm for the basic structure. This means that in amylopectin from potatoes the helical sections available for the adsorption of iodine bands are longer than those in amylopectin from maize [4]. In glycogen iodine accumulates in a diffuse manner without forming any long bands. For this reason, an absorption shoulder of merely 400 to 500 nm is found by photometry [4].A treatment with β‐amylase makes the situation even worse; only when the side‐chain stumps are separated by pullulanase does the formation of iodine bands in the basic structure of the glycogen improve to a maximum of 500 nm. This maximum corresponds to unramified sections of less than

ISSN:0038-9056    

DOI:10.1002/star.19900421202

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractStarch from the rhizomes ofCanna eduliswas isolated, purified and its physico‐chemical properties are compared with maize starch. Scanning electron microscopy of the granules show that they are oval to eliptical in shape. It has low contents of lipids, ash and proteins, and has significantly higher content of amylose. It displays low water‐binding capacity and gelatinization temperature. Swelling and solubility are higher when compared with maize starch. Brabender viscosity ofC. edulisstarch is more than three times higher than maize starch and has shown no thinning. It retrogrades more than maize sta

ISSN:0038-9056    

DOI:10.1002/star.19900421203

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractLaboratory isolated mung bean starch was fractionated into its amylose and amylopectin components using a modified procedure. The resulting products were shown to be both homogeneous and more susceptible to the hydrolyzing enzymes commonly used for structural analysis. The fine structure of the fractions was investigated using hydrolytic enzymes, chemical analysis and gel filtration chromatography. Differences in amylose/amylopectin fractions isolated by the modified and conventional extraction procedures were apparent. The unit chain length of amylopectin, DPnand limiting viscosity number of amylose were all lower for samples isolated by the modified method. In contrast the enzymatic hydrolysis of both the amylose and amylopectin fractions was improved for the material extracted by the modified method, low levels of branching and a unit chain distribution by gel filtration chromatography of the two overlapping populations with average degree of polymerization of 42 and 14 was obtained.

ISSN:0038-9056    

DOI:10.1002/star.19900421204

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractStarch may be determined by hydrolysis with α‐amylase and amyloglucosidase followed by specific measurement of glucose using glucose oxidase. However biological samples to be analysed for starch often also contain glucose, maltose and higher oligosaccharides derived from the hydrolysis of starch. These sugars may be difficult to remove quantitatively by solvent extraction. We have found that reduction with sodium borohydride followed by evaporation with 2,2 dimethoxypropane removed interference from glucose, maltose and the two reducing terminal residues from higher oligosaccharides. The specific glucose test was not sensitive to glucitol produced by reduction of free glucose. Maltitol was not hydrolysed significantly by the amyloglucosidase, removing interference from maltose and the two reducing terminal residues from higher polymers. The method has potential for monitoring the hydrolysis of starch especially in the mobilisation of starch reserves in plant tissues such as in the endosperm of germinating cereal grains. A reduction ratio based upon the method is proposed for use in characterising starch hydrolysat

ISSN:0038-9056    

DOI:10.1002/star.19900421205

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe extraction of wheat starch with ethanol reduced the protein content from 0.4 to 0.3%. Wheat starch extracted with 1% SDS containing 1% 2‐ME or with 1% SDS gave no staining with amido black, indicating that most of starch surface protein has been separated. TLC of lipids extracted from starch without gelatinization showed that ethanol extracted considerable amounts of starch lipids such as lysophosphatidyl choline, lysophosphatidyl ethanolamine and free fatty acids. After extraction with SDS and especially with SDS + 1% 2‐ME only some starch granules were deformed. In this starch some changes have been observed also on the granules surface by REM. The extraction resulted also in considerable changes in rheological properties of extracted starches. The starch samples were characterized thermodynamically a

ISSN:0038-9056    

DOI:10.1002/star.19900421206

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractStarches from corn and sorghum masas were solubilized in water and their molecular characteristics were studied with high‐performance, size‐exclusion chromatography (HPSEC). Rheological properties of masa (smoothness, plasticity and cohesiveness) that are developed during lime‐cooking, steeping and grinding of cereals were correlated to the starch solubility. Corn and sorghum were processed at different cooking times and grinding conditions; and the starch in masa was extracted with water at 85°C and 120°C for HPSEC analysis.Starches from corn and sorghum masas were affected in a similar way by the nixtamalization process; however, sorghum starch was more soluble than corn starch in flour and masa. Alkaline‐cooking, steeping and stone‐grinding did not depolymerize the cereal starch. All masas contained less than 10% soluble solids of which 30 to 50% was starch solubilized. Soluble solids increased with longer cooking time and finer grinding. About 50% of the insoluble starch, which remained in the particulate solids of masas was solubilized in water at 120°C. The remaining starch was indispersible because either the starch remained inside endosperm pieces or inside gelatinized and retrograded gels.Several granular and molecular forms of starch were present in masa as a result of partial gelatinization, i.e. uncooked, swollen, and annealed starch granules, and soluble and retrograded amylose. Retrogradationo f starch polymers occurred during steeping of cooked corn and during cooling of masa after grinding. Masa, a unique dough system, resulted from a network of starch polymers, uncooked and partially gelatinized starch granules supporting the rest of the kernel components into a continuous ph

ISSN:0038-9056    

DOI:10.1002/star.19900421207

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractUsing commercial pullulanase, α‐amylase and their mixture, partial hydrolysis of waxy corn starch was characterised for optimising production of maltodextrins free of D‐glucose. Compared to pullulanase or α‐amylase alone, the mixture of these two (simultaneous or successive addition) on the substrate enhanced the efficiency of maltodextrin turnover with low or traces of D‐glucose production in a short time. D‐glucose was removed from dextrins by membrane filtration and the yield of dextrin above DP6

ISSN:0038-9056    

DOI:10.1002/star.19900421208

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractGlucoamylase fromRhizopus niveuswas immobilized on Cellulofine, a kind of cellulose gel, to construct an enzyme‐Cellulofine structure, of which the molar activities k0for maltose and for soluble starch were found almost equal to 4 and 1/9 times, respectively, of those found with the intact enzyme. LiquefyingBacillusα‐amylase was fixed to make another enzyme‐Cellulofine structure, of which ratio of the molar activities, k0(modified)/k0(intact) for an oligomer substrate maltohexaose is much larger than those for high‐polymer substrates, amylose and soluble starch. These findings suggest that the substrate specificity of the amylase‐Cellulofine structure is improved to be useful for the enzyme‐catalyzed hydrolysis of saccharides having small degree of po

ISSN:0038-9056    

DOI:10.1002/star.19900421209

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900421210

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY

ISSN:0038-9056    

DOI:10.1002/star.19900421211

出版商:WILEY‐VCH Verlag GmbH    

年代:1990

数据来源: WILEY