en Fish processing Fish processing پژوهشي Orginal research papers The effects of Caper (<em>Capparis spinosa </em>L.) extracts on microbiological, chemical and sensory changes of rainbow trout (<em>Oncorhynchus mykiss</em>) fillets stored at 4 ˚C were evaluated. Trout fillets were dipped in Caper extracts (0.2 and 0.5%), packaged with or without modified atmosphere packaging (MAP; O₂ 5%, CO₂ 20%, N₂ 75%) and stored at 4 ˚C for 28 days. The data showed that lipid oxidation and spoilage of the samples were significantly delayed in the samples treated with Caper extract associated with MAP (<em>p</em><0.05). The acceptability limit (7 log CFU g^-1) of the psychrophilic bacterial counts was observed for MAP+Caper (0.5%) treatment in 7 and 14 days of storage time while it was reported for other treatments only in day 7. The use of 0.5 % Caper+MAP had the best antioxidative and antimicrobial effects, as well as sensory scores in the trout fillets during refrigerated storage (28 days) (<em>p</em><0.05). This study determined that the Caper associated with MAP had significant effects on shelf-life extension of fresh rainbow trout at cold storage period and could be a natural preservative for extending shelf life of fish fillets. Caper extract, Rainbow trout, Modified atmosphere packaging, Shelf life 272 285 http://jifro.ir/browse.php?a_code=A-10-2679-1&slc_lang=en&sid=1 P. Khadem pouryah1366@gmail.com 100319475328460032050 100319475328460032050 Yes Department of Health, Aquatic Animal Health and Disease, Faculty of Specialized Veterinary Science, Science and Research Branch, Islamic Azad University, Tehran, Iran A.A. Motalebi motalebi@ifro.ir 100319475328460032051 100319475328460032051 No Department of Health, Aquatic Animal Health and Disease, Faculty of Specialized Veterinary Science, Science and Research Branch, Islamic Azad University, Tehran, Iran N. Rokni n-rokni@srbiau.ac.ir 100319475328460032052 100319475328460032052 No Department of Health, Aquatic Animal Health and Disease, Faculty of Specialized Veterinary Science, Science and Research Branch, Islamic Azad University, Tehran, Iran V. Razavilar v-razavilar@srbiau.ac.ir 100319475328460032053 100319475328460032053 No Department of Health, Aquatic Animal Health and Disease, Faculty of Specialized Veterinary Science, Science and Research Branch, Islamic Azad University, Tehran, Iran