ABSTRACT
Although the intake of excess fat may result in significant health problems, it is important to note that fats are a critical part of a proper diet. The human body can produce most fatty acids but certain “essential” fatty acids (e.g.,
linoleic and linolenic acid) are typically derived from lipid-containing foods since the body cannot produce them. In addition, fats in foods are sources of vitamins A, D, E, and K. There is considerable evidence that therapeutic components that can improve human health are endogenous to food fats. Fats also contribute unique
I. Introduction ..........................................................................................................................................................8-1 II. Nomenclature........................................................................................................................................................8-2
III. Lipid Oxidation ....................................................................................................................................................8-2 A. Metals............................................................................................................................................................8-4 B. Heme Proteins ..............................................................................................................................................8-4 C. Peroxides ......................................................................................................................................................8-5 D. Role of Oxygen ............................................................................................................................................8-5 E. Lipoxygenases and Myeloperoxidases ........................................................................................................8-6 F. Lipolysis........................................................................................................................................................8-6 G. Photoactivated Sensitizers (Singlet Oxygen)................................................................................................8-6 H. Fat Content ....................................................................................................................................................8-6 I. Effect of Cooking..........................................................................................................................................8-6
IV. Measuring Rates of Lipid Oxidation in Food Systems ........................................................................................8-7 V. Antioxidants..........................................................................................................................................................8-7
A. Free Radical Scavengers ..............................................................................................................................8-8 B. Synthetic Phenolics ......................................................................................................................................8-8 C. Tocopherols and Tocotrienols ......................................................................................................................8-9 D. Plant Phenolics............................................................................................................................................8-10 E. Carotenoids ................................................................................................................................................8-10 F. Other Free Radical Scavengers and Reductants ........................................................................................8-11 G. Metal Inactivators........................................................................................................................................8-11 H. Enzymes That Inactivate Oxidation Intermediates ....................................................................................8-12 I. Scavenging of Lipid Oxidation Breakdown Products ................................................................................8-12 J. Other Mechanisms of Antioxidant Action ..................................................................................................8-12
K. Interfacial, Charge, and Location Effects ..................................................................................................8-12 VI. Production of Fats and Oils ................................................................................................................................8-13
VII. Modification of Lipids and Production of Specialty Fats ..................................................................................8-13 A. Hydrogenation ............................................................................................................................................8-13 B. Non-Enzymatic Interesterification ..............................................................................................................8-14 C. Enzymatic Modification of Lipids ..............................................................................................................8-14 D. Modification of Lipids Prior to Harvest ....................................................................................................8-15 E. Fat Replacers ..............................................................................................................................................8-15
VIII. Chemistry of Frying ..........................................................................................................................................8-16 IX. Food Irradiation ..................................................................................................................................................8-16
References ......................................................................................................................................................................8-17
sumers find desirable.
