317 17 Packaging and the Shelf Life of Vegetable Oils Luciano Piergiovanni and Sara Limbo Department of Food Science and Microbiology University of Milan Milan, Italy CONTENTS 17.1 Introduction ........................................................................................................................ 318 17.1.1 Vegetable Oil Sources and Markets ...................................................................... 318 17.1.2 Vegetable Oil Chemical Composition .................................................................. 319 17.1.3 Vegetable Oil Processing ...................................................................................... 320 17.2 Vegetable Oil Quality Attributes ......................................................................................... 320 17.2.1 Sensory Characteristics ........................................................................................ 321 17.2.1.1 Color .................................................................................................... 321 17.2.1.2 Odor ..................................................................................................... 321 17.2.1.3 Flavor................................................................................................... 321 17.2.2 Nutritional Characteristics.................................................................................... 321 17.2.2.1 Polyunsaturated Fatty Acids ................................................................ 321 17.2.2.2 Essential Fatty Acids ........................................................................... 321 17.2.2.3 Fat-Soluble Vitamins ........................................................................... 322 17.2.2.4 Natural Antioxidants ........................................................................... 322 17.2.3 Technological Characteristics............................................................................... 322 17.2.3.1 Heat Stability ....................................................................................... 322 17.2.3.2 Oil Crystallizability ............................................................................. 322 17.2.3.3 Emulsification Ability ......................................................................... 323 17.3 Deteriorative Reactions and Indices of Failure for Vegetable Oils..................................... 323 17.3.1 Enzymic Reactions ............................................................................................... 323 17.3.1.1 Lipases ................................................................................................. 323 17.3.1.2 Lipoxygenases ..................................................................................... 323 17.3.1.3 Polyphenoloxidases ............................................................................. 324 17.3.2 Oxidative Rancidity .............................................................................................. 324 17.3.2.1 Autoxidation Pathway ......................................................................... 324 17.3.2.2 Photo-oxidation Route......................................................................... 324 17.3.2.3 Oxidation-Derived Products ................................................................ 325 17.3.3 Loss of Natural Antioxidants................................................................................ 325 17.3.3.1 Tocopherols ......................................................................................... 325 17.3.3.2 Polyphenols ......................................................................................... 325 17.3.4 Oil Crystallization ................................................................................................ 326 17.3.5 Absorption of Flavor and Migration of Substances from Packaging ................... 326 17.3.5.1 Scalping ............................................................................................... 326 17.3.5.2 Migration ............................................................................................. 327 © 2010 by Taylor and Francis Group, LLC