Influence of extraction temperature on amounts and quality of rendered chicken fat recovered from ground or homogenized skin

Agriculture and Agri-Food Canada, Food Research and Development Centre, St-Hyacinthe, Quebec. Pietteg@em.agr.ca

A study was undertaken to determine the influence of extraction process on recovery and quality of fat from chicken skin. In order to do so, 20-kg batches of skin were ground (9.5 mm plate) or homogenized in a colloidal mill (0.2-mm knife set), then heated to 50 or 80 C to rupture fat cells. The fat was recovered by centrifugation and was evaluated for composition, appearance, and stability. A maximum amount of fat (89.6% of the fat initially contained in skin) was recovered from homogenized skin heated to 80 C, whereas heating ground skin to 50 C yielded the lowest fat recovery (51.5% of skin fat content). In general, fat composition and appearance were little affected by extraction conditions, with the exception that the fat extracted from homogenized skin contained more (P < or = 0.001) unsaponifiable cell membrane constituents (0.17 to 0.20%), including antioxidant tocopherol fractions (10.3 microg/ml), than the fat extracted from ground skin (0.08% and 7.5 to 8.3 microg/ml, respectively). This difference likely contributed to the greater oxidative stability of the fat extracted from homogenized skin, which was observed in Schaal oven tests.