Tehran University of Medical Sciences Journal of Food Safety and Hygiene 2476-3241 8 4 2022 12 26 237 242 Nastaran Akbarieh Division of Food Safety & Hygiene, Department of Environmental Health Engineering, School of Public Health, University of Medical Sciences, Tehran, Iran. Parisa Sadighara Division of Food Safety & Hygiene, Department of Environmental Health Engineering, School of Public Health, University of Medical Sciences, Tehran, Iran Nabi Shariatifar Division of Food Safety & Hygiene, Department of Environmental Health Engineering, School of Public Health, University of Medical Sciences, Tehran, Iran. Ebrahim Molaee-Aghaee Division of Food Safety & Hygiene, Department of Environmental Health Engineering, School of Public Health, University of Medical Sciences, Tehran, Iran Ramin Aslani Division of Food Safety and Hygiene, Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 2023 01 01 2023 01 29 Butter is popularly known in dairy products and consists of large amounts of milk fat (at least 80%). The risk of oxidation increases by a higher content of unsaturated fatty acids in milk fat and adversely affects the quality and safety of the product. Primary oxidation products are hydroperoxides, which can decompose to form lower molecular weight compounds such as alcohols, aldehydes, free fatty acids (FFA), and ketones. This process may give rise to butter rancidity. In this study, 20 samples of traditional butter, including 10 samples of cow butter and 10 samples of sheep butter, were purchased from different traditional dairy product supermarkets in southern Tehran and were analyzed to evaluate the amount of fat oxidation. The peroxide levels in all samples of traditional butter were within the permissible limit established by Iran's national standard. According to the results, it was found that the amount of peroxide in cow butter (1.08 ± 0.12 mEq/kg) is higher than in sheep butter (p=0.037). It may be related to the temperature and time of storage. Therefore, strategies such as diminishing temperatures, maintaining products in a dark environment, removing oxygen by creating a vacuum in the packaging, and using antioxidant compounds can prevent butter oxidation. https://jfsh.tums.ac.ir/index.php/jfsh/article/view/428 https://jfsh.tums.ac.ir/index.php/jfsh/article/download/428/204