RESULTS OF A COMPARATIVE-STUDY ABOUT METH ODS FOR ANALYSIS OF INTRAMUSCULAR FAT-CONTENT IN PIG LONGISSIMUS-DORSI MUSCLE BY EXTRACTION

Extractions by petroleum ether with and without acid pre-treatment as well by chloroform-methanol-mixture with and without extract-after-tre atment became at the determination of intramuscular fat (imf) content from musculus longissimus dorsi of pig together compared. In addition the residues of extractions without acid pretreatment were disintegrat ed with 2 N hydrochloric acid in iso-propanol-methanol-mixture (2:3, v /v) under boiling at reflux. Besides the analysis of the phosphor and nitrogen contents in imf occured to evaluate the portions of phospholi pids and nitrogen-containing compounds, which are also extracted. The chloroform-methanol-extraction with after-treatment of extracts by a 0 ,4 M sodium sulphate solution leaded to higher contents of imf and pho spholipids than the petroleum ether-extraction with acid pre-treatment . This method is prefered generally to the analysis of imf content wit h near infrared instruments (NIT/NIR) as reference and calibration met hod. The petroleum ether-extraction with acid pre-treatment covers mai nly neutral or depot lipids, which are important in breeding experimen ts. The phospholipids are destroyed by the acid treatment. The extract ion with petroleum ether without acid pre-treatment and the chloroform -methanol-method without after-treatment of extracts will give imf con tents which are to low respectively to high.