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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Key Terms
Antioxidants: Antioxidants are molecules that slow or prevent the oxidation of other chemicals. Oxidation is a redox chemical reaction that transfers electrons from a substance to an oxidizing agent. Oxidation reactions can involve the production of free radicals, which can form dangerous chain reactions. Antioxidants can terminate these chain reactions by removing radical intermediates and can inhibit other oxidation reactions by being oxidized themselves.
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Active Oxygen Method (AOM): AOM is a measure of the ability of a fat to resist oxidative rancidity during storage. An oil or fat is subjected to conditions known to accelerate degradation to help gauge the sample’s resistance to oxidation. Oxygen is bubbled into a fat to cause oxidation of the fatty acids. The peroxide value test is used to monitor oxidation after the sample is stressed under controlled conditions for a long time or until a specific peroxide value is achieved.
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Fatty Acid Profile (FAP): FAP is used to determine the quantities of each individual fatty acid, which make up the overall composition of the oil. It can be used as an identification aid and also to determine the composition of vegetable oil mixtures. The sample is reacted with methanol in the presence of a catalyst to form the methyl esters. These are injected onto a suitable chromatographic column, which splits the ester mixture into its various fatty acid components.
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Free Fatty Acids (FFA): Free fatty acids of fats and oils are primarily composed of various combinations of fatty acids bonded to a glycerin backbone. When fats and oils become rancid, individual fatty acids are “freed” and make the material slightly acidic. The FFA test measures this acidity and then expresses it on a fatty acid basis. The presence of high concentrations of free fatty acids in feed-grade fat, particularly “whole” animal fats, may mean the fat is rancid. However, some fat sources such as acidulated soap stocks can contain high amounts of free fatty acids without being rancid.
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Insoluble Matter (I): Contaminants found in used oils due to dust, dirt, wear particles or oxidation products. It is often measured as pentane, toluene or benzene insolubles to characterize the nature of the insoluble material.
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Iodine Value (IV): IV is identified as the number of centigrams of iodine absorbed by one gram of fat. Thus, it is a measure of unsaturation in fats and oils. While not a specific measure of fat stability, iodine number measures can indicate the potential of a fat to be oxidized. The method ensures the reaction of iodine with double bonds of unsaturated fatty acids. Fats with a great number of double bonds provide more sites for oxidation.
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MIU: MIU is an abbreviation for the tests Moisture, Insoluble Impurities and Unsafonifiable Matter. This value provides information about non-fat/oil components of food and feed grade fats and oils and is used primarily to screen incoming materials for industrial applications.
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Moisture (M): The amount of moisture in a material determined under prescribed conditions and expressed as a percentage of the weight of the moist specimen, that is, the original weight comprising the dry substance plus any moisture present. Moisture can be determined using thermogravimetric methods, moisture balance, Karl Fisher Titrator.
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Peroxide Value (PV): PV is the measure of the present state of rancidity of a sample. It is also called Initial Peroxide Value (IPV) because it is determined on a sample as submitted. Fresh non-rancid fats have a low PV – usually less than 5. The PV of unstabilized fat can change quickly. For this test, peroxides are indirectly measured under standardized conditions. The result is called the Peroxide Value, expressed as milliequivalents of peroxide per kilogram of fat.
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pH: pH is a measure of the activity of hydrogen ions (H+) in a solution and, therefore, its acidity or alkalinity. The pH value is a number without units, usually between 0 and 14, that indicates whether a solution is acidic (pH 7).
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Saponification Value: The saponification value is the weight in milligrams of potassium hydroxide needed to completely saponify one gram of fat. It can give additional indication of the average molecular weight of the fatty acids in a fat, but this test provides less useful information than the fatty acid composition determined by gas chromatography.
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Total Fatty Acids (TFA) Content: TFA is considered the sum of fatty acids expressed as triglicerides, which takes into account all sources of fatty acids in a food. This would include the fatty acids from mono-, di-, and triglycerides, other fatty acids, phospholipids and sterol esters.
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Unsaponifiable (U): Unsaponifiable matter includes those substances frequently found dissolved in fatty acids and drying oils that cannot be saponified by caustic treatment, but which are soluble in the normal fat solvents. Included are the higher aliphatic alcohols, sterols, pigments and hydrocarbons.
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