Supercritical fluid extraction as a method for fat content determination and preparative technique for fatty acid analysis in mesh feed for pigs

Abstract

Objective of this investigation was supercritical fluid extraction (SFE) with CO2, as analytical technique for total fat extraction from food and feed samples. Most significant advantages of this technique, compared with the others, are safety, cleanness, and shorter analysis time. Its main limitation includes difficulty of extracting polar lipids, due to the non-polar character of the CO2, which is used as a solvent. Influence of added absorbent and co-solvent on the SFE of mash pig feed was investigated in this paper. Total fat content was determined for ten commercially available mesh pig feeds. Optimization of absorbent weight and volume of added co-solvent showed that the maximum yield of extracted fat has been achieved at adsorbent mass of 1.8 g and ethanol volume of 0.54 ml. Yields of fat extracted with both Soxhlet method (AOCS Method Ba 3-38) and SFE were plotted one against the other. There were no significant (p > 0.05) differences between results of these two methods, which were confirmed by low value for standard deviation (SD). SFE appears to be reliable, faster, and less hazardous alternative for traditional extraction method. Fatty acid compositions from lipid extracts obtained by both methods were determined by gas chromatography-flame ionization detection (GC-FID). Results obtained by SFE were far more representative than results obtained by analyzing Soxhlet extracts, and in consistence with literature results. SFE method gave significantly higher (p < 0.001) contents of polyunsaturated fatty acids (PUFA) than Sohxlet method, especially of linoleic acid, C18:2 n-6. © 2011 Springer-Verlag.