Antioxidative effects of cottonseed meals as evaluated in cooked meat

Cottonseed meal samples were collected from nine cottonseed oil mills in the USA. The meal samples contained 230-1,820 ppm free gossypol and 8,300-16,480 ppm total gossypol. Finely ground meals were incorporated into ground beef with 15% fat or ground lean meats (beef semimembranosus muscle and goat lean composite), at 0-3% of the final meat mixture weight. The meat mixtures were cooked to an internal temperature of 77°C, aerobically refrigerated for 3 days, and analyzed for lipid oxidation using a distillation 2-thiobarbituric acid-reactive substances (TBARS) assay method. All the cottonseed meals were highly effective antioxidants in cooked meats, decreasing day-3 TBARS values by 77-91% with 3% addition. Estimated gossypol levels in the meat samples with 3% cottonseed meal were 7-55 ppm free gossypol (vs. the 450 ppm maximum limit set by the United States Food and Drug Administration for human food products) and 249-494 ppm total gossypol (vs. the 12,000 ppm maximum limit by the UN Food and Agriculture and World Health Organizations for food products). There was no significant correlation between the antioxidative efficacy of the meals and free or total gossypol levels.