Starch-iodine Color Research Articles

Some Physico-Chemical Properties of Non-Waxy Paddy Rice Starch in Niigata Prefecture

Fifteen samples of milled rice had protein contents ranging from 5.53 to 7.83% and amylose contents ranging from 17.6 to 22.1%. Eating and cooking qualities of cooked rice gave gross palatability indicies ranging from 100 to 61, cohesiveness values by balance method from 64 to 9, and starch-iodine color test values of milled rice from 0.297 to 0.574. Pasting characteristics of a 8% suspension of rice starch gave maximum viscosity values ranging from 550 to 380 Brabender Unit (B.U.), temperature at maximum viscosity from 82° to 92.5°C, break down values from 260 to 20B.U., and set back values from −0.5 to 60B.U. Good correlations were found between cooking and eating qualities of rice and rheological property of starch, and between rheological property and amylose content of starch, respectively.

Acid-stable α-Amylase of Black Aspergilli

Some general properties of the acid-stable dextrinizing amylase of black Aspergillus were investigated comparing with those of Taka-amylase A. The mode of action on starch of this amylase was quite similar to that of Taka-amylase A. Saccharifying degree at red point in starch-iodine color reaction was 5.1% and the limit of starch saccharification was a little over 40 per cent calculated as glucose with both amylases. Maltase activity was absent. Degradation products in the course of starch hydrolysis were also quite similar and they mutarotated downward. So this amylase was decided to be α-type. Thermal stability of the acid-stable α-amylase was higher than that of Taka-amylase A. Its acid stability was much higher than that of Taka-amylase A. Taka-amylase A was inactivated completely at pH 2.2, 37°C, for 30min, but the acid-stable α-amylase retained 87% of its original activity.

MODIFIED ASSAY FOR α-AMYLASE IN GERMINATING BARLEY

The activity of α-amylase is defined as the reciprocal of the time taken by a heat-treated malt extract to reduce the iodine-colouring capacity of a solution of soluble starch to half its initial value, under standardized conditions. Reasons are given for preferring starch iodine colour to reducing power measurements for following enzyme activity. α-Amylase is extracted from grain and contaminating enzymes are largely inactivated by heating a pulverized sample in a solution of calcium acetate. Boiled extracts of coloured malt make solutions of α-amylase less stable to heat. Precautions taken to achieve accurate sampling of enzyme digests and in measuring the starch iodine colour usefully improve the precision of the method. Results are calculated graphically using standard graph principles.

The interaction of human serum protein fractions with the starch-iodine complex

When starch-agar gel electrophoretic patterns are treated with iodine solution, decolorization in zones corresponding to the various protein fractions becomes more pronounced with time. This progressive loss of color cannot be ascribed entirely to the amylolytic activity since the starch-iodine reaction is influenced by serum proteins other than amylase. Increasing the starch concentration of iodine solution produces a relatively uniform rise in blue color intensity. However, this chromogenic response is greatly diminished by native human serum albumin or γ-globulin. The ability of these two fractions to dissipate starch-iodine color is lessened if the proteins are pre-iodinated. In the presence of fluoride, an amylase inhibitor, normal and pathologic sera are still capable of decolorizing starch-iodine solution to varying degrees. An interaction of serum proteins with available iodine would appear to account for this phenomenon.

A Study of the Starch-Iodine Complex: A Modified Colorimetric Micro Determination of Amylase in Biologic Fluids

Abstract The limitations, inaccuracies, and practical difficulties of saccharogenic methods are discussed. A modified colorimetric microdetermination of amylase is described in which the digestion of starch is measured by the decrease in the starch-iodine color. Experimental data show that there are two other serum factors that can also cause a fall-off in color: (1) an immediate 10-15% depression of color, probably due to serum proteins and countered by using serum in the control; (2) an acid-serum factor causing a progressive fall-off in color subsequent to the initial depression. Iodine prevents this, and must be added as soon as the acid has been added to stop the enzyme activity. Results of 189 consecutive assays of human sera are presented. Amylase activity of duodenal aspirate has been determined simultaneously by the method described and the Lagerlöf method. Results are compared. Changes in serum amylase and lipase levels in artificially produced pancreatitis in dogs are presented. Optimal conditions for amylase activity are reviewed, and in the light of these, different amyloclastic methods and their results compared. Achroic-point technics are briefly evaluated.

Serum Amylase Determination by Somogyi's Amyloclastic Method with Use of a Photometric End-Point

Abstract Somogyi's amyloclastic amylase assay has been modified by substitution of a spectrophotometric end point for visual observation, thereby increasing precision without changing the Somogyi assay units. A method of estimating starch concentration from the intensity of the starchiodine color reaction is described; absorbance is directly proportional to starch concentration. Somogyi's finding that corn starch is the substrate showing least variation inability to be degraded by amylase has been confirmed; a rapid method of standardizing the substrate is described. High amylase activities obtained using the amyloclastic method with sera containing lysed red cells are artifacts resulting from the interference of hemoglobin with the starch-iodine color reaction; the extent of the interference has been delineated, and means of avoiding it are described.

酵素による澱粉のヨード反応反転現象に就て

酵素による澱粉のヨード反応反転現象に就て

Photometric method for blood amylase by use of starch-iodine color.

Photometric method for blood amylase by use of starch-iodine color.

OBSERVATIONS ON AMYLOLYTIC BACTERIA: I. A SURVEY OF NAMED MESOPHILIC SPECIES ON SOLUBLE STARCH

A survey was made of the ability of known, named, mesophilic strains of 40 bacterial species lo hydrolyze soluble starch in trypticase–yeast extract broth. The 40 species are either not described in Bergey's Manual as to their action on starch or they are listed as "not hvdrolyzing starch". Strains of 35 species hydrolyzed soluble starch, including seven spp. described as nonamyloytic. The latter were: Micrococcus pyogenes var. aureus, M. citreus, M. luteus, Escherichia coli, Erneinia carotovora, E. atroscptica, and Flazobacterium rhenanus. Strains of lour species failed to hydrolyze starch in repeated at tempts: Micrococcus sphaeroides, Goffkya tetragene, Neisseria catarrhalis, Serratia, rubida, Rhizobium trifolii failed to grow. The disappearance of the substrate is a more permanent characteristic than either the accumulation of acids or of reducing sugars. Additional tests are required when the starch iodine color is still blue after two weeks of incubation. The initial pH seems to influence amylase formation. Pertinent literature is quoted supporting the findings.

酵素による澱粉のヨード反應反轉現象に就て

As reported previously, the reversion of starch-iodine color reaction is caused by α-amylase when amylose component is brought to helical micells by amylase-precipitants in the starch paste. Therefore, in the absence of the one component, either amylose or amylose-precipitant, this phenomenon is not observed. Various native starches give their specific reversion type according to their amylose contents and amount of amylose-precipitants. Voluntary reversion type is obtained by combining hot methanol extracts of native starches and defatted starches. As the amylose-precipitants of native sweet-potato starch, ordinary fatty acids, such as palmitic, stearic and oleic acid, jalapinolic acid (a saturated hydroxy-monocarboxylic acid) and octadecyl alcohol are recognized. Neutral fats and oils are not concerned with this reversion phenomenon.