Evaluation of the novel Soxflo technique for rapid extraction of crude fat in foods and animal feeds

The new Soxflo instrument was evaluated for the determination of crude fat in foods and animal feeds. Samples are packed into small columns and extracted with petroleum ether at room temperature. The Soxflo yielded accurate data from foods, ranging from 0.4 to 73.2% crude fat, compared with Soxhlet extractions and Certified Reference Materials, for which recoveries averaged 99.7 and 100.7%, respectively. Relative standard deviations (1.81%) were approximately half those of Soxhlet extractions (3.68%). Regression analysis of the data suggested that there was no proportional bias. A small but acceptable constant bias was measured. Soxflo extractions are easy to perform and take approximately 1 h to complete. The main difference between the Soxflo and Soxhlet techniques lies in the extraction procedure. Estimated savings during extractions are in time (85% reduction), energy (95%), cooling water (100%), and solvents (50%). Soxflo extractions are, therefore, more environmentally friendly than Soxhlet extractions.