Antioxidants, types

Antioxidant Types. Commercially available antioxidants may be divided into three general classes secondary amines, phenolics, and phosphites. 

Mid-Oleic Sunflower Oil With the relatively recent appearance of mid-oleic sunflower oil, researchers have shown an interest in its use in frying processes. Abidi and Warner (120) used the three types of sunflower oil (regular, high, and mid-oleic) in the preparation of french fries, potato crisps, and fresh white corn tortilla chips. However, no general conclusions may be drawn regarding inherent stability as there is no indication of antioxidant type and concentration in the different oils. 

See also Reactive Oxygen, Antioxidants, Types and Consequences of DNA Damage (from Chapter 25), Uric Acid... 

Although they do not appear to have been investigated in aromatic polyesters, there are a few other antioxidant types which might prove useful in this regard. 

Representative chemical structures of the various amine antioxidant types are shown in Figure 1. Similarly, phenolic antioxidants can also be subdivided by basic chemical types ... 

True antioxidants (type 1, see above) and reductants (type 2, see above) are used up during the shelf life, which implies that their content is much lower at the end of the shelf life than when the preparation was released. 

Antioxidant Types. Commercially available antioxidants may be divided into three general classes secondary amines, phenolics, and phosphites. In general, the amines are more active than the phenolics which in turn are more active than the phosphites. Amine antioxidants, however, often cause staining problems and are therefore used mainly in black-colored compounds. The phenolics and phosphites are relatively nonstaining and are normally used in light-colored elastomer formulas. Many antioxidants in these classes are volatile to some extent at elevated temperatures and almost all antioxidants are readily extracted from their vulcanizates by the proper solvent. These disadvantages have become more... 

Data were analysed using the Statgraphics software (STCC Inc., Rockville, Maryland). Multifactor analysis of variance, and multiple range analysis (Least significant difference, LSD) were done to determine the sources of variation in the data and the effects of antioxidant types, processing treatments and storage on the oxidation of the fish products. Tests of significance were done at the 99% confidence level (p < 0.01). 

Table 13.2 lists the FIA methods with amperometric detection developed for antioxidant analysis in food samples including the antioxidant type, sample, and limit of detection. 

Of the available antioxidant types, the peroxide decomposers, which produce a concentration variable induction period, are particularly valuable in controlling the induction period to oxidation. 

The choice of antioxidant type and the combination of additives influences several fiber properties. PP grades can be tailored to suit minimal degradation where mechanical properties (tenacity, elongation at break, etc.) are important or increased, but they have limited degradation where thermal bonding is a greater... 

Another potential discoloring reaction of phenolic antioxidants is their reaction with NO from the air, which is known as gas fading. NO from the atmosphere can, even at very low concentrations, convert phenolic antioxidants to quinone methides (for mechanism, see Scheme 18.10), which easily lead to discoloration. The discoloration due to gas fading is phenolic antioxidant type dependent, although all phenolic antioxidants are suffering from it. According to Yatchigo [86] the discoloration of not fully hindered phenolic antioxidants is less than that of fully hindered phenolic antioxidants. 

These relatively new techniques viz laser desorption/ionization Fourier transform mass spectrometry and fast atom bombardment and laser desorption Fourier transform ion cyclotron resonance mass spectrometry have been applied to the determination of non volatile polymer additives (thioester, phosphite, phosphonate and hindered amine antioxidant types) and antioxidants, ultraviolet absorbers and amide waxes. 

The amounts of PDl and analogous products (relative to polymer structures) [64, 65] indicate the conversion degree in oxidation transformations. The absence of these compounds in degradation products after reaction without oxygen testifies about exclusively thermal oxidation origin of their formation. Therefore, stabilization of heat-resistant polymers (HRP) displays clear antioxidant type, i.e. an additive is capable of interacting with radicals and other labile products of HRP thermal oxidation. 

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