Starch, Oxidized

Oxidized starches Oxidizers Oxidizing alkyds Oxidoreductases... 

Sodium chlorite oxidation of com and rice starches is recommended for the production of textile sizes (101) and oxidized starch is recommended as a hardening agent in the immobilization of microbial cells within gelatin (102). 

Oxidized starches, usually those prepared by hypochlorite oxidation, ate used in paper coatings and adhesives (qv) to improved surface characteristics for printing or writing. Oxidized starches may also be employed as textile warp sizes and finishes, in manufacture of insulation and... 

Oxidized starch, usually oxidized with sodium hypochlorite, is whiter than unmodified starch it has increased clarity and lower viscosity. 

Phosphated, oxidized starch with a molecular weight of 1500 to 40,000 Dalton, with a carboxyl degree of substitution of 0.30 to 0.96, is useful as a dispersant for drilling fluids [926]. 

E. K. Just and R. G. Nickol. Phosphated, oxidized starch and use of same as dispersant in aqueous solutions and coating for lithography. Patent EP 319989, 1989. 

Figure 30.3 C NMR spectrum of oxidized starch. (Signals at 171.6 and 180.5 ppm are attributed to carboxyl and aldehyde groups, respectively).

Acrylate and low-molecular-weight acrylic acids are effective slime depressants/disper-sants. Suspendol PKK and PC improved separation efficiency between zinc and iron oxides. Starches, mainly hydrolysed starch and cooked starch, are effective depressants in the treatment of oxidized zinc ores that contain iron oxides and Fe-hydroxides. 

Oxidized starches, 4 724t Oxidized wines, 26 316 Oxidizers... 

The oxidation of starch in aqueous suspension with H202 in the presence of iron phthalocyanine gives both carboxylic and carbonyl groups (Table 3.1). The best yields were obtained with a molar ratio 12900/1 (0.0078 mol%), but the oxidation was still quite efficient with 0.0039 mol% of catalyst [25800 per anhydroglucose unit (AGU)/catalyst ratio]. The oxidized starch had almost the same final Fe-content as the initial potato starch. Still, the efficiency of this method in view of scaling up was limited by comparatively low activity and product isolation problems. 

Significant volumes of low oxidized starch are used at the size press. These starches are made by treatment in alkaline suspension with sodium hypochlorite so that from 1 to 2% active chlorine acts on the starch. The reaction is simple to perform. However, the reaction products are complex. Chain scission occurs at the same time that carboxyl and carbonyl groups are formed in the starch. It is most desirable to prepare the highest ratio of carboxyl to carbonyl as possible and this reaction is a function of the pH in the slurry. 

Carbonyl groups contribute to cross-linking reactions where hemiacetals are formed. These are the greatest influence on viscosity build-up when low oxidized starches are used at neutral to acidic pH. When highly oxidized starches are used, the influence of the carbonyl group is much less because the molecular weight has been lowered and solubility is increased. The complexity of the reaction is shown in Figure 1. 

Lipophilic ointment (oil ointment) consists of a lipophilic base (paraffin oil, petroleum jelly, wool fat [lanolin]) and may contain up to 10 % powder materials, such as zinc oxide, titanium oxide, starch, or a mixture of these. Emulsifying ointments are made of paraffins and an emulsifying wax, and are miscible with water. 

Bleached or oxidized starches are produeed by reaeting starch with a specified amount of reagent under eontrolled temperature and pH. The starehes treated with low levels of reagents, sueh as hydrogen peroxide, peracetic acid, ammonium persulfate and sodium hypoehlorite, in aqueous slurry are referred to as bleached starches. 

Oxidized starches show reduced viscosity, transition temperatures, and enthalpies of gelatiniza-tion and retrogradation (Adebowale and Lawal, 2003). 

Oxidation also results in starch depolymerization, which is the cause of the low viscosity and improved clarity and stability exhibited by oxidized starches. Oxidized starches are used in foods as coating and sealing agents in confectionary, as an emulsifier and as a dough conditioner for bread, whereas bleached starches are used for improved adhesion of batter and breading mixes in fried foods. 

Figure 7.12 Sequence of CLSM images recorded during melting of a 24-hour-old fractal particle gel formed by quenching a 1 wt% gelatin + 7 wt% oxidized starch system from 40 to 24 °C (a) immediately before heating (b) network rearrangement and coarsening (c) network break-up (d) aggregate melting into polydisperse liquid droplets. Reproduced from Firoozmand el al. (2007) with permission.

Figure 8.14 CLSM images showing the initial development of the microstructure of a phase-separated mixed biopolymer system (25.5 wt% sugar, 31.4 wt% glucose syrup, 7 wt% gelatin, and 4 wt% oxidized starch pH = 5.2, low ionic strength) containing 0.7 wt% polystyrene latex particles (d32 = 0.3 pm). The sample was quenched from 90 to 1 °C, held at 1 °C for 10 min, heated to 40 °C at 6 °C min-1, and observed at 40 °C for various times (a) 2 min, (b) 4 min, (c) 8 min, and (d) 16 min. White regions are rich in colloidal particles. Reproduced from Firoozmand et ai (2009) with permission.

The focus of this work was to determine if a glyco-peptide or a simple dextrinized, oxidized starch could be produced which would enhance the behavior of a starch-based polymer for spray dried flavoring production. Enhancement of a starch s lipophilic/hydrophilic balance was anticipated to maintain the polymer s film forming" and cohesive wall development during the spray drying process while improving its emulsifying/interfacial activity capabilities. 

Oxidized Starch Production Methods. Multiple methodologies were utilized to produce the corn starch products of hypochlorite and periodate oxidation. Ultimately only three of these procedures were selected as yielding functional product and will, therefore, be the only methods to be outlined here. 

The finished gelatinized, oxidized starch was cooled to 30 C in a water bath, dialyzed and spray dried. 

Dextrose Equivalency. Corn starch dextrose equivalent values (de) were usedto measure the carbonyl groups present in both dialdehyde, oxidized starch production and the production of dextrinized starches (26). 

Characterization of both the Control and Oxidized starches was completed by examining emulsion stabilty, vapor phase flux, dryer retention values of added lemon oil (Table II),... 

Given the excellent lemon oil-incorporated emulsion stabilities of both polymers, the excellent dryer retention performance of the Control material and good lemon oil retentions using the Oxidized starch, scaled-up systems were prepared and dried. One... 

Covalent linkage of amino acid, peptide or protein moieties onto the hydrolyzed and/or oxidized polymers (Control and Oxidized starches) was examined for its ability to improve the potential for microregion lipophilicity within the carbohydrate polymer. Proteinaceous materials are often strongly surface active (39) and may, if carefully selected, contribute positively to wall material characteristics. This selection process was carried-out using maltodextrins (DE 10 and/or 25) as the carbohydrate framework and various amino acid-derived materials as the function-altering accessory, ranging from gelatin and casein proteins to simple amino acids. 

The addition of phenylalanine to the previously described starch base materials (Control and Oxidized starches) was done on a lOX (w/w) level for covalent attachment. The Oxidized starch was apparently more conductive to cyanogen bromide activation for amino acid attachment than was the Control starch (92X attachment versus 67X, respectively). The addition of aspartame was also completed for the Oxidized (ii) starch polymer on a level of... 

Substantial improvement (about 50%) of lemon oil encapsulation efficiency was attained for the covalently-linked phenylalanine-Oxidized starch wall material over the Oxidized starch control. In fact, this particular glycoamine resulted in lemon oil retentions following drying in the mini-spray dryer which surpassed both the Control and lipophilic starches (See Table IV). Dry blending phenylalanine with the Oxidized starch base exhibited the benefits associated with covalently linked glycoamine production via lemon oil vapor phase flux analysis. 

The other two glycoamine derivatives failed to substantially improve polymer performance. Aspartame linkage to the Oxidized starch resulted in improved lemon oil encapsulation efficiency over the Oxidized material, alone, but not to the extent of the phenylalanine glycoamine polymer. Covalent attachment of phenylalanine to the Control starch was actually a slight detriment to lemon oil retention versus the control starch (48.7% retention in the mini-dryer versus 50.4%, respectively), although this difference was not deemed significant. 

Oxidized Starches. Alkaline hypochlorite treatment introduces carboxyl and carbonyl groups, effects some depolymerization, and produces whiter (bleached) products that produce softer, clearer gels. Ammonium persulfate is used in some paper mills with continuous thermal cookers to prepare in situ bigb solids, low viscosity dispersions. Most of the hypochlorite-oxidized starch and all the ammonium persulfate-oxidized starch is used in the paper industry. The low solution viscosity and good binding and adhesive properties of these products make them especially effective in high solids, pigmented... 

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