Preservatives hydrogen peroxide

Catalase Aspergillus niger Shelf life improvement of food Milk preservation Hydrogen peroxide removal... 

Other apphcations of sodium bromide iaclude use ia the photographic iadustry both to make light-sensitive silver bromide [7785-23-1] emulsions and to lower the solubiUty of silver bromides during the developing process use as a wood (qv) preservative in conjunction with hydrogen peroxide (14) as a cocatalyst along with cobalt acetate [917-69-1] for the partial oxidation of alkyl side chains on polystyrene polymers (15) and as a sedative, hypnotic, and anticonvulsant. The FDA has, however, indicated that sodium bromide is ineffective as an over-the-counter sleeping aid for which it has been utilized (16). 

The iodometric method has the advantage over the permanganate method (Section 10.95) that it is less affected by stabilisers which are sometimes added to commercial hydrogen peroxide solutions. These preservatives are often boric acid, salicylic acid, and glycerol, and render the results obtained by the permanganate procedure less accurate. 

The slight excess of sulfite can be left to use as a kind of preservative or be destroyed using oxidizing agents like hydrogen peroxide. One has to be careful in leaving oxidants or reductants in the product. There might be some difficulties when the sulfosuccinate comes in contact with dyes. 

In the reaction following the second pathway, the 0-0 bond is not broken while the first two electrons are added it is preserved in the HjOj produced as an intermediate, and breaks in a later step, when the hydrogen peroxide is reduced or cat-alytically decomposed. An analog for this pathway does not exist in anodic oxygen evolution. 

It has been shown in many studies that protective effects of carotenoids can be observed only at small carotenoid concentrations, whereas at high concentrations carotenoids exert pro-oxidant effects via propagation of free radical damage (Chucair et al., 2007 Lowe et al., 1999 Palozza, 1998, 2001 Young and Lowe, 2001). For example, supplementation of rat retinal photoreceptors with small concentrations of lutein and zeaxanthin reduces apoptosis in photoreceptors, preserves mitochondrial potential, and prevents cytochrome c release from mitochondria subjected to oxidative stress induced by paraquat or hydrogen peroxide (Chucair et al., 2007). However, this protective effect has been observed only at low concentrations of xanthophylls, of 0.14 and 0.17 pM for lutein and zeaxanthin, respectively. Higher concentrations of carotenoids have led to deleterious effects (Chucair et al., 2007). 

Hydrogen peroxide is used as a sterilant or preservative for milk and whey it destroys harmful micro-organisms. Any excess hydrogen peroxide left in the milk or whey after treatment can be decomposed to water and oxygen using an enzyme (catalase). 

In a ground flask fitted with a long air-condenser are placed 25g of iodine, 50ml of concentrated nitric add, and 15ml of 30% hydrogen peroxide (free of organic preservatives). Twenty-five milliliters of water are added and the vessel is heated at 70°C until the reaction begins, as shown... 

If sampling is not followed immediately by analysis, the sample must be treated with a preservative, but not such as to falsify the analytical results use is made of 10% potassium dichromate solution, formaldehyde, hydrogen peroxide, alcoholic solution of phenol, mercuric chloride (about 5% solution), etc., a few drops being added. The last of these preserves milk very well for several days without altering its composition or disturbing the determinations, but its poisonous character necessitates precautions. 

To preserve the contact time r = 10 s, the molar ratio of reagents was varied by changing hydrogen peroxide concentration in the initial aqueous solution. Regularities observed from curves in Figure 7.29 can be explained in the framework of catalase and monooxygenase conjugation ideas (see above). 

Despite the differences between the functions implemented by hydrogen peroxide in gas, liquid and biological oxidation processes, they are united by a specific feature H202 first transforms to a higher reactive form in which the donor-acceptor properties of the original compound are preserved, and then only (in this new form) oxidizes the substrate according to the conjugated mechanism. 

It has been suggested that hydrogen peroxide and iron are the cause of this rapid depolymerization (30). It is possible that the initial attack by micro-organisms is not enzymatic but hydrolytic and oxidative in nature. If this is true, then a preservative system could be based on anti-oxidant properties of the chemical. If the initial attack can be stopped, then the total attack has been stopped. It is also possible that the initial and sustained attacks are caused by a combination of chemical... 

Pour, in a thin stream, with constant stirring, the hydrogen peroxide solution into the barium hydroxide solution in the 2-liter bottle. Let the flaky barium peroxide hydrate settle and then collect it on a suction filter. As soon as the water is drawn out, shut off the suction, wash with 15 cc. cold water, press the solid into a compact cake, and again suck dry. Do not draw any quantity of air through the product. Wrap the crystals in paper towels and dry them according to Note 9 (6), page 15. Preserve the product in a 4-ounce cork-stoppered bottle. 

A 30 or 40 per cent by volume hydrogen peroxide is used as bleach for silk, wood, Wool, bones, teeths, feathers, mother of pearl, hom, hair, coral, gelatine, oils and fats. In medical science it is an excellent disinfectant and is also essential for sterilizing water for municipal use and preserving milk. Apart from this, hydrogen peroxide is used in the chemical industries for the manufacture of persalts and in laboratories for oxidation. 

Having in mind the inhibitory effect of hydrogen peroxide on peroxidases, the procedure of peroxide addition influences the preservation of the enzymatic activity into the system. The peroxide can be added in a portionwise, continuous, or feed-on-demand mode, by using a peroxide-stat [8, 86], as was mentioned before in Sect. 10.1.2. When adding peroxide in a continuous mode, a low concentration of this reactant and thus less enzyme deactivation are ensured. 

The hydrogen peroxide does not accumulate unless the experimental conditions are specially arranged for its preservation, since... 

Preservation.—On account of its instability and even explosive tendency it is advisable to use hydrogen peroxide in the form of a solution, a concentration of 30 per cent, being suffident for most purposes, whilst much more dilute solutions will often satisfy the needs of experi-... 

Lignin-preserving oxidative bleaching is almost exclusively carried out with sodium peroxide. Hydrogen peroxide is a weak acid, which is dissociated according to the following equation ... 

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