Validation of a high liquid chromatography method (HPLC) for simultaneous quantification of skatole and indole in porcine fat

Boar taint is a meat quality defect that may lead to an unpleasant experience during the consumption of meat and meat products with negative economic repercussions for food industry. It can occur when meat or fat from entire male pigs is heated, due to excessive accumulation of skatole, indole and androstenone (1). For a fast identification and quantification of skatole and indole, an high-pressure liquid chromatography analytical method, coupled with a fluorimetric detector (HPLC-FD), has been set up and validated. The extraction of the target analytes (skatole, indole and internal standard, 2-methylindole) from lipid matrix (approximately 0.5 ± 0.05 g of subcutaneous fat taken from female pigs at slaughterhouse) was performed by sample liquefaction, addition of pure methanol and separation of the organic solvent was obtained by cooling and centrifugation steps (2). Chromatography separation was achieved using a simple isocratic HPLC method (3). In addition to the limit of detection (LOD) and quantification (LOQ), linearity, recovery, accuracy and sensitivity were evaluated for the validation of the method. A good linearity was confirmed by the correlation coefficient (R2) of the standards calibration curves always ≥ 0,99, together with the recovery from matrix for both analytes, always ≥ 96%. The precision of the method, intra-and inter-assay, expressed as relative standard deviation (RDS%) was good for each analyte, always below the limit of 10%. Good results were obtained also for LOD and LOQ, amounting to 1,562 ng/g and 2,312 ng/g for both compounds, concentrations far lower than those perceived by human smell. The proposed method is suited for rapid routine analyses because of its high sensitivity and precision, required by small sample size and was always reliable to identify and quantify target compounds in all samples analyzed. The follow application of the method to samples (28) taken at slaughterhouse by different subjects (sows, entire and castrated male), has allowed always to identify and quantify skatole and indole, confirming the robustness of the method. The small sample size of sample used, allow the application of the method also to samples of fatty tissue taken from pigs by subcutaneous biopsy.