Lipid oxidation and colour in pressure- and heat-treated minced chicken thighs

Lipid oxidation and colour in pressurised and heated chicken samples were evaluated. In a preliminary test, raw and overcooked (100degreesC/60min) minced chicken thighs were pressurised (500MPa/50degreesC/30min). Samples were stored at 4degreesC in contact with air. Thiobarbituric acid reactive substances (TBARS) were quantified at 1, 6 and 9days. Pressure induced oxidation in chicken, but overcooking generated many more secondary oxidation compounds. In a second experiment, raw minced chicken thighs were pressurised (50OMPa/-10, 5, 20 and 50degreesC/30 and 60min) or cooked (90degreesC/15min). Samples were vacuum stored at 4degreesC. TBARS were measured at 1 and 9 days, whereas colour parameters (L, a, b and DeltaE) were determined at I day. No differences in TBARS values were observed between untreated and pressurised samples, whereas cooked samples presented the highest values. Pressurisation for 30 and 60min generated similar TBARS contents. At 9 days, oxidation values did not increase. Pressurisation and cooking induced marked colour changes. Pressurised samples were lighter and less red than untreated ones. Samples pressurised at 50degreesC were the palest and, together with cooked samples, presented the lowest a values. Therefore pressurised chicken thigh cannot be marketed as a fresh product but can be incorporated as an ingredient in ready-to-eat meals. (C) 2004 Society of Chemical Industry.