ABSTRACT
CONTENTS 20.1 Introduction ........................................................................................................ 428
20.1.1 Nomenclature of Lipids ......................................................................... 428 20.1.2 Key Aspects of Lipolysis and Related Enzymatic Reactions ................... 428 20.1.3 Industrial Uses of Lipolytic Enzymes .................................................... 430
20.2 Lipolytic Determination ..................................................................................... 432 20.2.1 Methods ............................................................................................... 433 20.2.2 Turbidimetric Assays ............................................................................ 433
20.2.2.1 Agar Plate Assays or Gel Di usion Assays ............................ 433 20.2.3 Titrimetric Assays ................................................................................. 433
20.2.3.1 ADV and BDI Methods ....................................................... 433 20.2.3.2 pH Stat Method ................................................................... 434
20.2.4 Spectrophotometric Assays.....................................................................435 20.2.4.1 Chromogenic Substrates ........................................................435 20.2.4.2 Fluorimetric Assays .............................................................. 438 20.2.4.3 Infrared ................................................................................ 439
20.2.5 Radioactive Assays ................................................................................ 439 20.2.5.1 Radiolabeled Substrates ........................................................ 439
20.2.6 Chromatographic Methods ................................................................... 440 20.2.6.1 in-Layer Chromatography ................................................ 440 20.2.6.2 Gas Chromatography ........................................................... 440 20.2.6.3 Liquid Chromatography ...................................................... 441
20.2.7 Immunological Methods ...................................................................... 443 20.2.7.1 Enzyme-Linked Immunoassays Methods ............................. 443
20.2.8 Surface Tension Methods ..................................................................... 443 20.2.8.1 Oil Drop Method................................................................. 443 20.2.8.2 Monomolecular Films (Wilhelmy Plate Method) ................ 444
References ...................................................................................................................... 444
20.1 Introduction Bovine milk lipids are similar to other mammalian species as they are mainly composed of triacylglycerides (∼98.3%, w/w), diacylglycerides (0.3%), monoacylglycerides (0.03%), free fatty acids (0.1%), phospholipids (0.8%), sterols (0.3%), with trace amounts of fat-soluble vitamins, β-carotene, and fat-soluble avoring compounds [1]. Triacylglycerides exert a major direct e ect on the properties of milk due to their high levels in milk fat. Milk fat contains many di erent combinations of triacylglycerides that vary in molecular weight, degree of unsaturation, and number of carbon atoms. e complexity of triacylglycerides is a result of the wide array of di erent saturated or unsaturated fatty acids (>400) that can be esteri ed on the hydroxyl groups of a glycerol molecule to form di erent acylglycerides. Milk fat contains approximately 50 mol% longchain saturated fatty acids and 15 mol% short-to medium-chain saturated fatty acid mixtures [2]. Milk fat contains over 250 di erent fatty acids, but 15 of these make up 95% of the total fatty acid content [3] (Table 20.1).
