Rancidification

Rancidification is the process of sort up or incomplete oxidation or hydrolysis of fats together with oils when exposed to air, light, or moisture or by bacterial action, resulting in unpleasant taste as well as odor. Specifically, this is a the hydrolysis or autoxidation of fats into short-chain aldehydes, ketones and free fatty acids, which are objectionable in taste and odor. When these processes occur in food, undesirable odors and flavors can result.

Incases, however, the flavors can be desirable as in aged cheeses. In processed meats, these flavors are collectively call as warmed-over flavor.

Rancidification can also detract from the nutritional expediency of food, as some vitamins are sensitive to oxidation. Similar to rancidification, oxidative degradation also occurs in other hydrocarbons, such as lubricating oils, fuels, and mechanical cutting fluids.

Pathways

Three pathways for rancidification are recognized:

Hydrolytic rancidity specified to the odor that develops when triglycerides are hydrolyzed and free fatty acids are released. This reaction of lipid with water may require a catalyst such(a) as a lipase, or acidic or alkaline conditions leading to the lines of free fatty acids and glycerol. In particular, short-chain fatty acids, such as butyric acid, are malodorous. When short-chain fatty acids are produced, they serve as catalysts themselves, further accelerating the reaction, a relieve oneself of autocatalysis.

Oxidative rancidity is associated with the degradation by oxygen in the air.

The unsaturated fatty acid can be cleaved by free-radical reactions involving molecular oxygen. This reaction causes the release of malodorous and highly volatile aldehydes and ketones. Because of the variety of free-radical reactions, the reaction is catalyzed by sunlight. Oxidation primarily occurs with unsaturated fats. For example, even though meat is held under refrigeration or in a frozen state, the poly-unsaturated fat will go forward to oxidize and slowly become rancid. The fat oxidation process, potentially resulting in rancidity, begins immediately after the animal is slaughtered and the muscle, intra-muscular, inter-muscular and surface fat becomes reported to oxygen of the air. This chemical process supports during frozen storage, though more slowly at lower temperature. Oxidative rancidity can be prevented by light-proof packaging, oxygen-free atmosphere air-tight containers and by the addition of antioxidants.

A double bond of an unsaturated fatty acid can be oxidised by oxygen from the air in reactions catalysed by plant or animal lipoxygenase enzymes, producing a hydroperoxide as a reactive intermediate, as in free-radical peroxidation. Theproducts depend on conditions: the lipoxygenase article shows that whether a hydroperoxide lyase enzyme is present, it can cleave the hydroperoxide to yield short-chain fatty acids and dicarboxylic acids several of which were first discovered in rancid fats.

Microbial rancidity subjected to a water-dependent process in which microorganisms, such as bacteria or molds, use their enzymes such as lipases to break down fat. Pasteurization and/or addition of antioxidant ingredients such as vitamin E, can reduce this process by destroying or inhibiting microorganisms.