Tocopherols lipid storage

Meat products have to be stabilised in some cases, as meat lipids contain no natural antioxidants or only traces of tocopherols. Most muscle foods contain, however, an efficient multi-component antioxidant defence system based on enzymes, but the balance changes adversely on storage. The denaturation of muscle proteins is the main cause of the inbalance as iron may be released from its complexes, catalysing the lipid oxidation. Salting contributes to the negative effects of storage, as it enhances oxidation. Using encapsulated salt eliminates the deleterious effect of sodium chloride. 

It is well known that meat lipids are stable during freezer storage of fresh meats for periods of up to 12 months or more (5). Recent work has shown that a-tocopherol levels declined steadily during storage and had largely disappeared by the end of 6 months in freezer storage (J8). In contrast to the involvement of phospholipids in development of WOF in cooked... 

Li, S.X., Ahn, D.U., Cherian, G., Chung, T.Y., Sim, J.S. 1996. Dietary oils and tocopherol supplementation on cholesterol oxide formation in freeze-dried chicken meat during storage.. / Food Lipids 3, 27 42. 

The oxidative stability of lipids depends on several factors, including the degree of unsaturation, nature of unsaturation (position of double bonds), antioxidant content (tocopherols and synthetic antioxidants), prooxidant content (trace metals and enzymes), and storage conditions (exposure to heat, light, oxygen, and moisture). 

Deficiencies. The current model for the cause of vitamin E deficiencies points to malabsorption of lipids. Thus, there may be malabsorption of other lipid-soluble vitamins. Little is known regarding the pharmacokinetics of the tocopherols. Part of the reason for this may be attributed to lack of a specific storage organ for the vitamin. 

Contrary to the lipids in animal prodncts, plant lipids always contain natural antioxidants, mostly tocopherols (Hall, 2001 Yanishlieva and Heinonen, 2001). They control the oxidation that occnrs dnring storage, bnt they are slowly consumed by inhibition reactions with free radicals. Therefore, the resistance of plant lipids to oxidation slowly decreases on storage, especially in the presence of light. 

Oxidative lipid deterioration in milk and dairy products occurs mainly during storage. The rate of oxidation depends on the concentration of dissolved oxygen, the storage temperature, and the presence of antioxidants (a-tocopherol, p-carotene)... 

Soon after harvest, tree nuts, because of their high concentrations of unsaturated fatty acids, may undergo development of oxidative rancidity. This leads to the formation of undesirable rancid flavors and a decline in both unsaturated fatty acids (e.g., oleic, linoleic, and linolenic acids) and natural antioxidants (e.g., tocopherols) [63]. The postharvest stability and sensory quality of tree nuts are influenced by several factors such as chemical composition (e.g., fatty acid composition and presence of antioxidants such as tocopherols), moisture content, oxygen concentration, and temperature, among others. There is some evidence that lipid oxidation is at least in part due to the action of oxidative enzymes, such as lipoxygenases. This is supported by the fact that mild to moderate heat treatment of some nuts, such as pecan, retards the development of rancid flavors during storage [64,65]. Nevertheless, mild oxidation is probably necessary for the development of the characteristic volatile flavor components of natural tree nuts [63], In addition to the Upid oxidation volatiles, some other compounds, such as terpenes, lactones, and short-chain volatile acids, may impact the aroma profiles of some types of natural flee nuts. 

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