[Determination of intramuscular fat in beef by means of extraction with chloroform-methanol]

In a comparison on samples of muscular substance from 53 fattening bulls the extraction of intramuscular fat with a chloroform-methanol mixture yielded results about 1.23% higher than those obtained with the extraction with diethyl ether. This difference results from the extraction of additional water-soluble nitrogenous compounds by the chloroform-methanol mixture. These compounds were isolated by adding water to the chloroform-methanol extract; their analysis by means of chemical and spectroscopic methods revealed, among other compounds, creatinine and threonine. The fat values obtained for the ether extract were closely correlated with those found for the chloroform-methanol extract (r = 0.925). In a variant where water was added to the chloroform-methanol extract, the correlation was less close (r = 0.925). In a variant where water was added to the chloroform-methanol extract, the correlation was less close (r = 0.660). The chloroform-methanol extraction may be used instead of the ether extraction. A regression calculated from the present data permits, if required, to convert the values thus obtained into the values yielded by the ether extraction method. Apart from its high precision, the chloroform-methanol extraction has the special advantage that it requires relatively simple safety measures and that its energy demand is low.