Comparing the use of chloroform to petroleum ether for Soxhlet extraction of fat in meat

Context. Soxhlet extraction is commonly used for determining fat content of meat, because it is the basis of the AOAC Final Action method for this analysis. Petroleum ether is used as an extraction solvent but other solvents, such as chloroform, can be used. Chloroform has been stated to be a safer solvent than petroleum ether and is used extensively for Soxhlet extraction for meat research in Australia; yet, there has been no report that validates its use for this purpose. Aim. To compare the use of chloroform with that of petroleum ether as an extraction solvent for Soxhlet fat extraction in beef. Methods. The fat content of six beef samples, reported as chemical lean (CL, 100 - %fat), was determined using Soxhlet fat extraction with chloroform (bytwo independent research providers) and petroleum ether (b.p. 40-60 degrees C, using three commercial providers). Passing-Bablok regression and Bland-Altman plot analysis were used to identify any differences and bias between the methods respectively. Key results. Passing-Bablok regression showed that there was no difference between the use of chloroform and the use of petroleum ether as a solvent for Soxhlet fat extraction in beef. Bland-Altman plot analysis indicated that there was no bias evident between the uses of each solvent. Thus, this would indicate that chloroform can be used as a solvent for Soxhlet fat extraction, providing equivalency to petroleum ether. While some minor differences were apparent, this is most likely attributable to sample heterogeneity. Conclusions. Chloroform was found to provide equivalency to petroleum ether for fat extraction from meat. While some minor differences were apparent in the fat content of meat, this has been attributed to likely sample heterogeneity. Implications. Chloroform can be used as an extraction solvent for Soxhlet fat extraction of beef.