Antioxidants sources

Antioxidants are not important only to the health conscious food manufacturers also rely on these chemicals to maintain the shelf life of their products. Synthetic antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate and tert-butyl hydroquinone were widely used in food processing to control oxidation and maintain food quality. However, as these synthetic antioxidants are suspected to be carcinogenic they now have restricted use in food (Madahavi and Salunkhe, 1995). Therefore, natural antioxidant sources, especially of plant origin, are of great interest to the food industry. 

Because fruits and vegetables are the major antioxidant sources in the daily diet of humans, we calculated estimated dally antioxidant capacity intake from these foods. 

Figure 2-17 Determination of Protection Factor. (A) lard, (B) lard + antioxidant. Source From J. Pokorny, Stabilization of Fats by Phenolic Antioxidants, Can. Inst. Food Sci. Technol. J., Vol. 4, pp. 68-74, 1971.

Fruits are important natural antioxidant sources. Several epidemiological studies suggest that vegetables and fruits have a protective effect against chronic diseases, due to the presence of compoimds with healthrelevant effects, independent of the well-known nutrients and micronutrients (Agudo etal. 2007 Huxley and Neil 2003). Compoimds such as... 

Brewer, M. S., 2011. Natural Antioxidants Sources, Compounds, Mechanisms of Action, and Potential Applications. Comprehensive Reviews in Food Science cmd Food Safety 10, 221-247. 

Rajalakshmi, D., S. Narasimhan, Food antioxidants Sources and methods of evaluation in D. L.Madhavi, S. S. Deshpande, D. K. Salunkhe, Food Antioxidants, New York Marcel Dekker, Inc., 1996, pp. 70-71. 

Table 3 Dietary antioxidants source, bioavaiiabiiity, and concentrations in human plasma...

Peroxide-decomposing antioxidants destroy hydroperoxides, the sources of free radicals in polymers. Phosphites and thioesters such as tris(nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, and dialkyl thiodipropionates are examples of peroxide-decomposing antioxidants. 

Typically, soHd stabilizers utilize natural saturated fatty acid ligands with chain lengths of Cg—C g. Ziac stearate [557-05-1/, ziac neodecanoate [27253-29-8] calcium stearate [1592-23-0] barium stearate [6865-35-6] and cadmium laurate [2605-44-9] are some examples. To complete the package, the soHd products also contain other soHd additives such as polyols, antioxidants, and lubricants. Liquid stabilizers can make use of metal soaps of oleic acid, tall oil acids, 2-ethyl-hexanoic acid, octylphenol, and nonylphenol. Barium bis(nonylphenate) [41157-58-8] ziac 2-ethyIhexanoate [136-53-8], cadmium 2-ethyIhexanoate [2420-98-6], and overbased barium tallate [68855-79-8] are normally used ia the Hquid formulations along with solubilizers such as plasticizers, phosphites, and/or epoxidized oils. The majority of the Hquid barium—cadmium formulations rely on barium nonylphenate as the source of that metal. There are even some mixed metal stabilizers suppHed as pastes. The U.S. FDA approved calcium—zinc stabilizers are good examples because they contain a mixture of calcium stearate and ziac stearate suspended ia epoxidized soya oil. Table 4 shows examples of typical mixed metal stabilizers. 

Animal Feed. In animal feeds (1—3% lecithin) lecithin is an emulsifier wetting and dispersiag agent energy source antioxidant surfactant source of choline, organically combiaed phosphoms and iaositol and Hpotropic agent. It is used ia a milk replacer formula for calves (approximately 10,000 t of lecithin ate used for this purpose) and for veal production, ia mineral feeds, poultry feeds, fish foods, pet foods, and feeds for fur-beating animals (30). 

Applications. These materials are stiU in developmental infancy. Current production is limited to one commercial process in Europe and a demonstration-scale process in North America. The lignins produced in these processes have potential appHcation in wood adhesives, as flame retardants (qv), as slow-release agents for agricultural and pharmaceutical products, as surfactants (qv), as antioxidants (qv), as asphalt extenders, and as a raw material source for lignin-derived chemicals. 

Fertile sources of carotenoids include carrots and leafy green vegetables such as spinach. Tomatoes contain significant amounts of the red carotenoid, lycopene. Although lycopene has no vitamin A activity, it is a particularly efficient antioxidant (see Antioxidants). Oxidation of carotenoids to biologically inactive xanthophyUs represents an important degradation pathway for these compounds (56). 

Butadiene reacts readily with oxygen to form polymeric peroxides, which are not very soluble in Hquid butadiene and tend to setde at the bottom of the container because of their higher density. The peroxides are shock sensitive therefore it is imperative to exclude any source of oxygen from butadiene. Addition of antioxidants like /-butylcatechol (TBC) or butylated hydroxy toluene (BHT) removes free radicals that can cause rapid exothermic polymerizations. Butadiene shipments now routinely contain about 100 ppm TBC. Before use, the inhibitor can easily be removed (247,248). Inert gas, such as nitrogen, can also be used to blanket contained butadiene (249). 

To obtain maximum lifetime, the oxidants must not be lost during service. A major potential source of loss is the evaporation of the antioxidant. Evaporation is often observed with BHT (butylated hydroxytoluene), a monomeric phenol, and to avoid evaporation less volatile, higher molecular weight antioxidants are used (i.e. bisphenols). 

One excellent UV protector for foods is PABA, a B vitamin. Likewise, many of the same antioxidants we ingest as health supplements—such as vitamin C and a similar chemical, erythorbic acid vitamin E and lecithin, a source of the important nutrients choline and inositol—occur naturally in food. 

The final possible mode of action for an antioxidant is as a peroxide decomposer. In the sequences that lead to photodegradation of a polymer the ready fragmentation of the hydroperoxide groups to free radicals is the important step. If this step is interfered with because the peroxide has undergone an alternative decomposition this major source of initiation is removed. The additives which act by decomposing hydroperoxide groups include compounds containing either divalent sulfur or trivalent phosphorus. The mechanism involves... 

Therefore, there is substantial evidence that GA can play a positive health-related role in addition to its well-known properties as an emulsifier. Therefore, the aim of this chapter is to describe general aspects of the source, composition, and already known uses of GA as well as some new aspects of its antioxidant capacity against some reactive oxygen substances (ROS), and its antimicrobial activity (AMA). 

Epinephrine is an inherently unstable chemical in aqueous solution, even at a low pH and in the presence of an antioxidant such as sodium metabisulfite, up to 1 mg/ ml. With the passage of time, the epinephrine dose gradually decreases due to degradation into inactive compounds. If the expiry date has passed, the epinephrine dose correlates inversely with the number of months or years past that date, and will likely be lower than the dose stated on the label even if the solution appears clear and colorless. Nevertheless, if this is the only source of epinephrine available for injection, it should be used in preference to not administering epinephrine at all [32]. 

Vitamin C occurs as L-ascorbic acid and dihydroascorbic acid in fruits, vegetables and potatoes, as well as in processed foods to which it has been added as an antioxidant. The only wholly undisputed function of vitamin C is the prevention of scurvy. Although this is the physiological rationale for the currently recommended intake levels, there is growing evidence that vitamin C may provide additional protective effects against other diseases including cancer, and the recommended dietary allowance (RDA) may be increased in the near future. Scurvy develops in adults whose habitual intake of vitamin C falls below 1 mg/d, and under experimental conditions 10 mg/d is sufficient to prevent or alleviate symptoms (Bartley et al., 1953). The RDA is 60 mg per day in the USA, but plasma levels of ascorbate do not achieve saturation until daily intakes reach around 100 mg (Bates et al., 1979). Most of the ascorbate in human diets is derived from natural sources, and consumers who eat five portions, or about 400-500 g, of fruits and vegetables per day could obtain as much as 200 mg of ascorbate. 

The aim of our project was to study phloem as a source of fiber and polyphenols, and to develop a method to improve its taste without losing the potentially bioactive polyphenols. In addition, we wanted to investigate the bioavailability, cholesterolemic and antioxidative effects and safety of phloem and its phytonutrients in humans in a randomised double-blind trial. 

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