Validation of two laboratory methods for beef intramuscular fat quantification

Abstract

Many studies on beef nutritional qualities require the quantification of intramuscular fat. To reduce the sample amount, solvent use and time of analysis, two alternative methods to the Folch et al. (1957) reference method were studied: a miniaturised Folch's method and a near-infrared spectroscopic method. Performances and acceptability limits were evaluated with accuracy profiles for each of the methods. Equations to correct bias between the alternative and reference methods were calculated. Uncertainties associated with measurements were determined, and the validity domains were defined. From a previous set of studies, the ability of each method to discriminate samples from bovines of different breeds or receiving diverse treatments was tested. The validity domain of the miniaturised Folch's method ranged from 1.9 to 13.8 g of total lipids/100 g of tissue, and that of the near-infrared spectroscopic method ranged from 4.8 to 13.8 g of total lipids/100 g of tissue, with less than 20% difference from the reference method's results. Thus, the two alternative methods could be used depending on the research objectives: the miniaturised Folch's method could be used for detailed quantification of intramuscular fat and the near-infrared spectroscopic method for a quick classification of a large number of muscles. The precise knowledge of uncertainties associated with each measurement was determined, and perfect continuity with the results obtained so far with the reference Folch's method was confirmed.

Keywords: Accuracy profile; Discrimination threshold; Lipid extraction; Meat; Method validation; Near-infrared spectroscopy.