51B-2

T. A. DOANE-WEIDEMAN¹, P. B. Liescheski, J. S. Tomczak, and G. E. Walker. (1) Isco, Inc., 4700 Superior St., Lincoln, NE 68504

Total fat analysis is a standard determination performed in food laboratories on both raw materials and finished products. It can be used as a means to monitor process efficiency. Additionally, the total fat content must be declared on the label for both nutritional and regulatory compliance. Most of the current methods for the determination of fat use hazardous or flammable reagents. Supercritical carbon dioxide would be a beneficial alternative in that it uses almost no solvents and lipid materials are highly soluble in supercritical CO2.

The objective of our work was to quantitatively extract fat from several different sample matrices using supercritical fluid extraction (SFE) and compare the accuracy and precision of the SFE method with that of an AOAC approved method.

Precision of the methods was determined using two frozen potato products and two emulsified products. These samples were gravimetrically assayed for fat content in duplicate for 5-10 days using both SFE with carbon dioxide and AOAC methods that employed acid hydrolysis followed by solvent extraction. Verification was accomplished by comparing the fatty acid profiles generated by each method using gas chromatography (GC/FAME).

Our results show that the repeatability, which is the variation between duplicate samples on the same day, of SFE and AOAC methods are comparable producing values of 0.21-0.43% and 0.36-0.65% respectively for the potato products and 0.21-0.34% and 0.34-0.39% respectively for the emulsified products. Reproducibility, which is the variation between the average values on different days, was also found to be comparable between SFE and the AOAC method. Both methods report statistically the same average %fat value.

The results suggest that SFE using carbon dioxide should be considered as a standard method for the determination of total fat in high moisture potato products and emulsified products.