Deterioration in food quality due to lipid oxidation

Lipids play a vital role in the metabolism of cells by providing a source of energy and reserve storage materials. There are many catalytic systems that can oxidize lipids. Among these are light, temperature, enzymes, metals, metalloproteins and microorganisms.

Cations in foods, such as Fe2+ and Cu2+, may induce a diversity of undesirable effects that influence the nutritional quality of foods. Iron actively catalyses lipid oxidation and its presence even in trace amounts has long been recognized as potentially detrimental to the shelf-life of fats, oils, and fatty acids.

Lipid oxidation is one of the major causes of quality deterioration in natural and processed foods. Oxidative deterioration is a large economic concern in the food industry because it affects many quality parameters such as flavour (rancidity), colour, texture, and the nutritive value of foods. Oxidation can occur in both triglycerides and phospholipids of food because lipids are divided into two main classes; polar lipids (phospholipids) and neutral lipids (triglycerides).

Oxidation affects many interactions among food constituents, leading to both desirable and undesirable products. Food lipids are the foods components that are most susceptible to oxidation, therefore oxidation reactions are one of the major sources of deterioration that occurs during manufacturing, storage, distribution and final preparation of foods.
Deterioration in food quality due to lipid oxidation 

Lipid oxidation

Lipid oxidation is a major cause of food quality and flavor deterioration. It is important reaction that limits the shelf life of many foods. Oxidation of lipids is primarily dependent on the degree of unsaturation of their fatty acid constituents.

It is also affected by other components present in the food matrix as well as conditions under which the product is stored.

Deterioration of foods by lipid oxidation generally displays an induction period during which very little oxidation occurs. This is followed by a stage when deterioration process rapidly.

Lipid oxidation which is also called autoxidation as it occurs in bulk fats and oils proceeds via a self sustaining free radical mechanism that produces hydroperoxides that under scission to form various secondary products include aldehydes, ketones, organic acids and hydrocarbons.

Significant of lipid oxidation is not limited to the development of off-flavors in food, but it also affects the nutritional value of food as it brings about loss of essential polyunsaturated fatty acids, fat-soluble vitamins, protein value and destruction of pigments when present.
Lipid oxidation