Oxidation Of Starch Research Articles

Mild oxidation of starches with aqueous bromine : Part I. Kinetics and product analysis

Starch suspensions have been treated with dilute, aqueous bromine at 30° in the pH range 6–8; no adsorption of oxidant occurred. The oxidation kinetics were first-order in bromine and in accordance with the rate law d [bromine]/d t  k [starch] [bromine], except for a minor, initial rapid-phase in the oxidation of cereal starches, which is attributed to an enhanced reactivity of the granule surface. The apparent first-order rate-constants were 2.0–2.8 x 10 −3 min −1, except for retrograded amylose oxidised at pH 8 when the value was 5.6 x 10 −3 min −1. The i.r. spectra of the products indicated the presence of carboxylate and aldehyde groups. The functional group contents were determined quantitatively. Oxidation of the amylose at pH 6–7 introduced carbonyl groups, whereas at pH 8 carbonyl and carboxylate were found in equal amounts. For waxy-maize starch oxidised at pH 6–8, the carbonyl content was twice that of carboxylate. Acid hydrolysis of the product obtained by oxidation of amylose proceeded at pH 8 according to first-order kinetics. Chromatographic analysis of the anionic components of the hydrolysate indicated the presence of D-glucurono-6,3-lactone, D-gluconic acid, and an unidentified acidic ketose.

Kinetics and Mechanism of Oxidation of Carbohydrates with Chlorine and its Derivatives

AbstractThe examination of heterogeneous starch oxidation with hypochlorite in buffered systems showed that the oxidation rate was highest at pH 7. During starch oxidation in unbuffered systems the pH of the solution decreased. The hydroxyl groups of starch take an active part in the oxidation rate which decreased when C‐2 and C‐3 hydroxyls were blocked. Investigation of oxidation with chlorine in light and in heavy water suggests that the formation of protons in the acidic medium and repulsion between anions in the alkaline medium decrease the oxidation rate.

Mild oxidation of starches with aqueous bromine. : Part II. Solution viscosity of the oxidised starches

Mild oxidation of starches with aqueous bromine. : Part II. Solution viscosity of the oxidised starches

Oxidation of Starch by Hydrogen Peroxide in the Presence of UV Light‐Part II

AbstractVarious reaction variables in the hydrogen peroxide oxidation of starch in the presence of UV light have been investigated. Higher carboxyl and carbonyl contents of oxystarches were obtained under acidic than under alkaline conditions. Extent of oxidation was found to increase with time. Increasing the concentration of hydrogen peroxide results in an increase in the carboxyl and carbonyl contents. Apparently, air has no effect on the degree of oxidation whereas, oxygen seems to accelerate it.

Oxidation of Starch by Hydrogen Peroxide in the Presence of UV Light ‐ Part. I

AbstractOxidation of starch in the presence of hydrogen peroxide and UV light has been investigated. This new procedure furnished oxidized starch containing significant amounts of carbonyl and carboxyl contents. The use of reagents such as ferrous sulfate or hypochlorite in our hydrogen peroxide oxidation of starch in the presence of UV light did not offer any advantage.

Chemical Process for Making Dialdehyde Starch

AbstractA practical, strictly chemical process has been developed for the periodic acid oxidation of starch to dialdehyde starch. In the procedure spent oxidant is converted by alkaline hypochlorite to insoluble sodium paraperiodate, which is recovered in high yield for recycling. The process is suitable for small‐scale production of dialdehyde starches of various carbonyl contents.

Air‐Oxidation of Starch Using Quinquevalent Vanadium as Catalyst

AbstractAir‐oxidation of corn starch in the presence of ammonium meta vanadate at 35–40°C and pH 9 has been studied. The resulting oxidized starch contained more carbonyl but less carboxyl as compared to an industrial oxidized starch. However, the presence of undesirable amounts of the catalyst imparted extremely high viscosity to the oxidized starch.The ultraviolet irradiation was found to have a pronounced effect on the air oxidation of starch in the presence of ammonium meta vanadate. Increased carboxyl content was observed in the UV light catalyzed oxidized starch.

Oxidation of Starch by Dimethyl Sulfoxide

Oxidation of Starch by Dimethyl Sulfoxide

The interaction of starch with bromine in acid solution

Amylose is precipitated from aqueous solution by the tribromide ion and can thus be separated from amylopectin. The adsorption of bromine by dissolved amylose was demonstrated potentiometrically. The rate of oxidation of starch by bromine at pH 1.7, 3.0, and 5.9 is a fist-order reaction with respect to bromine, and increases rapidly with the pH.

FORMATION OF CYCLIC O-2′-HYDROXYETHYLIDENE ACETALS FROM POLYALCOHOLS OF 4-O-LINKED POLYSACCHARIDES

Partial acid hydrolysis of polyalcohols derived from some 1,4-O-linked polysaccharides gave cyclic O-2′-hydroxyethylidene derivatives as by-products in yields of 6–18%. Polysaccharides containing β-links such as Rhodotorula glutinis mannan and cellulose gave rise to 6-membered ring acetals with lesser amounts of the 5-membered ring form. On the other hand, two α-linked polyalcohols, obtained following partial and complete oxidation of starch with sodium periodate, were converted to 5-membered O-2′-hydroxyethylidene acetals.

Ozone oxidation of corn starch

AbstractThe oxidation of granular corn starch with ozone under various conditions was investigated. The reaction was found to be influenced by water, with the highest degree of oxidation being obtained at 23°C. in an aqueous solution of acetic acid as the suspending medium. In each medium investigated, approximately 65–75% of the total carbonyls generated were found to be aldehydes. Approximately similar results were obtained when aqueous solutions of the sugar alcohols sorbitol and mannitol were ozonized.

The Light-Catalyzed Oxidation of Starch with Aqueous Chlorine

The Light-Catalyzed Oxidation of Starch with Aqueous Chlorine

THE TAXONOMIC SIGNIFICANCE OF THE OXIDATION OF CARBON COMPOUNDS BY DIFFERENT STRAINS OF MICROCOCCUS LUTEUS.

The oxidation of 17 carbon compounds by 13 strains ofMicrococcus luteus was studied. It was shown that all strains oxidized Na-acetate, Na-lactate, glycerol, glucose, galactose, sucrose, maltose and fructose. The oxidation of mannitol, sorbitol, xylose, ribose, rhamnose, starch, lactose and arabinose was variable. Dulcitol was not oxidized at all. We have shown that the species, considered byKocur andMartinec (1962) to be identical withM. luteus, possess the same oxidation pattern.

Oxidation of wheat starch

Oxidation of wheat starch

Oxidation of wheat starch

AbstractA series of samples of oxidised wheat starch was prepared by treating the starch with varying amounts of aqueous sodium hypochlorite, extent of oxidation being followed by estimation of carboxyl and of carbonyl content of each sample; viscosity changes on heating with water were followed by means of the Brabender Amylograph, and paste viscosities at 40° were also determined. The results were compared with those obtained from a commercial sample of oxidised maize starch.

A contribution to the theory of periodate oxidation of starch

AbstractThe mathematical theory of periodate oxidation of unfractionated starches was studied. The degrees of polymerization (DP) of the amylose and amylopectin components of the starch were considered to be unknown, whereas the proportion of amylose in the starch, the repeating chain length of the amylopectin component, and the amount of formic acid evolved on quantitative oxidation were considered to be experimentally ascertainable and thus known. The treatment thus reduces to an approximate solution of one equation with two unknowns. It is shown that certain inequalities are then valid, when the following information can be obtained: (1) the upper and lower DP limits of each component, (2) the extent of degradation of a randomly degraded starch, and (3) the maximum relative errors involved in the determination of the DPs of the components by the periodate method. A numerical example is given to show the application of the method in laboratory practice.

A Study of the Mild Oxidation of Wheat Starch and Waxy Maize Starch by Sodium Hypochlorite in the Alkaline ph Range

A Study of the Mild Oxidation of Wheat Starch and Waxy Maize Starch by Sodium Hypochlorite in the Alkaline ph Range

A kinetic study of the mild oxidation of wheat starch by sodium hypochlorite in the alkaline pH range

Abstract(1) Some kinetic aspects of mild oxidation of wheat starch by sodium hypochlorite in the pH range 7.5–11.0 were studied. (2) No significant chlorate formation was observed at any time. From this and from other experimental evidence it is concluded that the reaction is most likely to be purely chemical in type and to proceed according to the overall scheme: (3) The reaction appears to be of the first order with respect to starch. (4) The reaction appears to be of the first order with respect to hypochlorite at pH = 8.0. At pH = 9.0 and 10.0, the reaction velocity is still approximately proportional to the concentration of the oxidant present, but the course of the reaction appears to be more complicated. (5) The reaction rate decreases with increasing pH of the oxidizing medium. An approximate empirical equation is proposed adequately representing the interdependence of the first‐order constant and pH in the pH range 7.5–10.0. (6) The activation energy of the reaction is within the range of 21–23 kcal./mole, i.e., that obtained for many homogeneous, truly chemical reactions. (7) The fact that the reaction rate of a starch solution is about 50% higher than the corresponding rate for a starch suspension would seem to indicate that the number of sites available for oxidation in a granule is about two‐thirds of that available when that granule is dissolved. (8) The addition of neutral salts had an accelerating effect on the reaction rate. Under the experimental conditions of the present paper, this effect was negligible, but at much higher salt concentrations it would have to be taken into account.

Some effects of 2,4-dinitrophenol on the metabolism of tobacco leaf disks

1. 1. Respiration of tobacco leaf disks in an atmosphere of oxygen at 25°C was at first stimulated and then inhibited by increasing concentrations of 2:4 dinitrophenol (DNP). Starch was at first the respiratory substrate, but at concentrations of DNP above 8·10 −6 M starch loss was strongly inhibited, although respiration was rising. 2. 2. Leaf disks depleted of starch and supplied with sucrose as substrate showed a response to DNP qualitatively similar to that of disks from normal leaves as regards respiration, and in addition starch synthesis was inhibited. In both cases respiration quotients ( R Q ) were a little over 1.0 and fell as DNP concentrations increased over 5·10 −5 M. In the absence of added sucrose, R Q was about 0.75, and respiration was again stimulated by DNP. 3. 3. Taken together the data suggest that oxidation of starch or sucrose was gradually inhibited by DNP, and was progressively replaced by the non-carbohydrate substrate with R Q 0.75. This conclusion is supported by the observation that when radioactive sucrose was used as substrate w the relative specific activity of the CO 2 fell with increasing DNP concentration, indicating increasing use of unlabelled substrate. 4. 4. The results are discussed in relation to the hypothesis that DNP uncouples oxidative phosphorylation.

An investigation of the polysaccharide content of oats, Avena sativa L.

AbstractA graded extraction procedure has been applied to the polysaccharides present in the kernels of oats, Avena sativa L. Analyses of the sugar, protein and ash content of the fractions obtained are reported. A method for the purification of the starch present in the kernels is given. Oxidation of the unfractionated starch with potassium metaperiodate showed that the ratio of terminal to non‐terminal glucose units was 1 to 27.4. Differential potentiometric iodine titrations indicatied the presence of 26.0% of amylose in the starch, and hence the average length of unit‐chain in the amylopectin component was calculated to be 20.3 glucose units. Examination of the impure intermediate starch products showed that the protein impurity interfered considerably with the interaction of the starch with potassium metaperiodate.