Direct saponification: A simple and rapid method for determination of total cholesterol and fatty acid composition of aquatic foods

Total cholesterol in aquatic foods was determined by direct saponification coupled with gas chromatography without derivatization. The direct saponification was compared with an AOAC extraction procedure and a culture tube extraction technique, both using chloroform:methanol (1:2, v/v) for extraction. Gas chromatography, high-performance-liquid-chromatography with UV detection of conjugated enone of cholesterol at 240 nm, and spectrophotometric o-phthalaldehyde method at 550 nm were compared to determine their effectiveness in cholesterol measurement. Direct saponification generally gave higher contents of cholesterol than the AOAC and culture tube extraction procedures, while quantification by the GC procedure appears to be the simplest method without sacrificing accuracy. Average percentage recoveries of cholesterol estimated with direct saponification-GC analysis in spiked fat-free catfish matrix and spiked fresh catfish muscle were 101.8 +/- 9.6% and 101.7 +/- 1.9%, respectively. The method may also be adaptable to food ingredients other than sterols such as the determination of fatty acid composition as demonstrated in this paper.