Soxtec: Its Principles and Applications

The classical Soxhlet method provides the fundamental basis for a modern-day solvent extraction system, the SoxtecTM. Using the Randall modification, sometimes called the submersion method, the Soxtec provides a faster approach to solvent extraction for the gravimetric quantitation of fat and oil. Typically, the Soxtec methods require only 20–25% of the time required for traditional Soxhlet extraction. Sample preparation, general extraction procedures, method considerations, and optimization are addressed. By definition, the procedure to determine “crude fat” is an empirical method in which the result is determined by the conditions of the procedure. Several aspects of the extraction process, such as solvent type, time, and temperature, are explored. Several standardized Soxtec methods are discussed, including the recently approved AOAC method for determining crude fat in feeds, cereal grains, and forages. Many Soxtec applications are routinely used in food, feed, industrial, and environmental laboratories for the measurement of fats, oils, semivolatiles, and other solvent “extractables.” For the determination of crude fat, descriptions are given for various sample pretreatment and extraction procedures. Practical guidelines for handling challenging samples as well as general suggestions are presented.