Fat Analysis

Determination of food lipid content is important because of regulatory requirements, nutritive value, and functional properties. This chapter includes the typical required sample preparation steps of predrying the sample, particle size reduction, and acid hydrolysis. The majority of the chapter covers the instrumentation, principles, procedures, advantages, disadvantages, and applications of various fat determination methods. The total lipid content of foods is commonly determined by organic solvent extraction methods, based on the solubility characteristics of lipids. Common extraction methods are continuous (e.g., Goldfisch), semicontinuous (e.g., Soxhlet), or discontinuous (e.g., Mojonnier). Solvent extraction followed by gas chromatography analysis is required for nutrition labeling. Nonsolvent wet extraction methods, such as the Babcock or Gerber, are commonly used for certain types of food products. Instrumental methods, such as nuclear magnetic resonance (NMR), infrared, accelerated solvent extraction (ASE), supercritical fluid extraction (SFE), and X-ray absorption, are also available as rapid methods that may be useful for quality control.