en تخصصي Special Original article Original article <p style="text-align: justify"><span style="font-family:times new roman"><strong>Background:</strong> In recent years, there has been an increasing interest in using food additives from natural sources to improve taste and also extend shelf life of semi-preserved food. The aim of this paper was to examine chemical and microbiological changes promoted by a traditional marinating process in rainbow trout fillets during frozen storage.</span></p> <p style="text-align: justify"><span style="font-family:times new roman"><strong>Methods:</strong> Fish fillets were immersed in traditional marinades and stored at -18 ^&deg;C for 56 days. Some chemical and microbial characteristics like total volatile basic nitrogen (TVN), thiobarbituric acid (TBA), water holding capacity (WHC), pH, mesophilic, and psychrophilic bacterial count were performed with 7 days interval. The results were analyzed by repeated measure ANOVA test using SPSS 16.0 software.</span></p> <p style="text-align: justify"><span style="font-family:times new roman"><strong>Results:</strong> Data showed that although the value of TVN, TBA and, WHC in marinated samples were higher than control ones, but the differences were not significant (<em>p</em>>0.05). The numbers of bacteria in marinated samples were lower than control groups and for psychrophilic bacteria was significant (<em>p</em><0.05).</span></p> <p style="text-align: justify"><span style="font-family:times new roman"><strong>Conclusion:</strong> The most obvious finding to emerge from this study is that rainbow trout flesh could be marinated and stored at -18 ^˚C for at least 56 days with no major unfavorable changes.</span></p> Analysis, Food Quality, Frozen Foods, Trout 128 133 http://jfqhc.ssu.ac.ir/browse.php?a_code=A-10-1-117&slc_lang=en&sid=1 S. Maktabi s.maktabi@scu.ac.ir Yes Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran M. Zarei No Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran M. Chadorbaf No Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Iran