Quantification of synthetic phenolic antioxidants in liver pâtés

Pâtés are products with high fat levels and their consumption has increased in Portugal over the past few years. Owing to their composition, lipid oxidation is one of the primary mechanisms associated with deterioration of their quality. Therefore, antioxidants have become a useful group of food additives because they help to maintain the organoleptic quality of pâtés by avoiding rancidity. The aim of this work was the evaluation of seven synthetic antioxidants with phenolic structure, namely, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), propyl (PG), octyl (OG) and dodecyl gallates (DG) and nordihydroguaiaretic acid (NDG), in liver pâtés available on the Portuguese retail market. The high performance liquid chromatography (HPLC) procedure described in AOAC for oils and fats was found to be inappropriate for pâtés, probably owing to their complex matrices. A modification of the Association of Official Analytical Chemists (AOAC) extraction procedure is thus presented. Extensive validation of this extraction procedure was carried out by recovery tests. Over 91% recoveries of added antioxidants were observed, except for PG and OG whose recoveries were 78.0±2.2 and 82.1±1.1 1%, respectively. The precision found was below 3.8%. No synthetic antioxidants were detected in six of the 12 assayed brands. One sample contained BHA and five samples contained NDG (concentrations ranged from trace levels to 26.3±0.0 mg/kg of product). When pepper corn was added as an additive to pâtés, piperine (the main compound of pepper) appeared on the chromatogram but it did not interfere with the evaluation of the other antioxidants.