Pro-oxidant metals

Metal deactivators—Organic compounds capable of forming coordination complexes with metals are known to be useful in inhibiting metal-activated oxidation. These compounds have multiple coordination sites and are capable of forming cyclic strucmres, which cage the pro-oxidant metal ions. EDTA and its various salts are examples of this type of metal chelating compounds. 

Polyethylene is sensitive to pro-oxidant metals such as copper, manganese or cobalt, which must be avoided as inserts. 

The foods can be protected against lipid oxidation either by the addition of antioxidants or by packaging in vacuum or inert gases to exclude oxygen. The antioxidants can be of various types. They can work as "chain-breakers" that interfere with the free radical chain reaction, as "metal inactivators", that bind otherwise pro-oxidative metals, or as "peroxide destroyers", which react with hydroperoxides to give stable products by nonradical processes (1). 

Polyethylene film samples containing pro-oxidant metal additives, LDPE-DCP540, FCB-ZSK15, and FCB-ZSKIO were provided by EPI Environmental... 

With physical rehning, the oil is first degummed and bleached and then fed to a continuous distillation (deodorization) unit, which removes the free fatty acids (92-95%) and volatiles. The rehned oil is blended as above. Frequently, distillation is stopped before removal of all of the free fatty acids, and the oil is alkali rehned to remove the remainder of the free fatty acids. This procedure has the advantage of ehminahng oxidation byproducts and pro-oxidant metals, thus improving product stabihty. 

Various mechanisms have been proposed for the mode of action of phospholipids as antioxidants or antioxidant synergists, including chelation of pro-oxidant metals (106, 108), the release of protons that bring about the rapid decomposition of hydroperoxides without generating free radicals (107), and the regeneration of... 

Naturally occurring gums, phospholipids, pro-oxidant metals, pigments, color bodies, tocopherols, free fatty acids, and diacyglycerols... 

Five factors contribute to the oxidative deterioration of fats and oils (1) oxygen or air (2) heat (3) light (4) pro-oxidant metals and (5) time. 

Bleaching is popularly and correctly regarded as the partial or complete removal of color. However, it is also a purification process to prepare the oil for further processing. Bleaching is relied upon to remove the traces of soap, phospholipids and pro-oxidant metals, remaining after caustic neutralization and water washing, that hinder filtration, poison the hydrogenation catalyst, darken the oil, and adversely affect the flavor of the finished oil. Another function, considered primary by many processors, is the removal of peroxides and secondary oxidation products. These impurities compete for space on the adsorbent surface of the filter media. 

It has been extensively shown that pecific feeding regimes can increase the concentrations of boh polyunsaturated lipids and pro-oxidative metal pedes, which boh make he milk more prone to autoxidation (6 7 8 9 10). Thus several studies have been perfomted to limit autoxidation in milk through optimized feeding (II 12). Moreover, numerous studies have shown that antioxidants in he feed are transferred to he milk and hereby improve he oxidative stability of milk. It has been reported hat increasing concentrations of dietary vitamin E can effectively reduce he intensity of oxidized flavor in milk (13 14). Recent studies confirm hat a-tocopherol protects milk fat from oxidation (IS). In contrast, earlier studies have not been able to show hat... 

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