EVALUATION OF SHELF LIFE OF LIVE AND GUTTED FISH TREATED WITH A SHALLOT EXTRACT SAMANEH PEZESHK 1 , HEDAYAT HOSSEINI 2,3 , MASOUD REZAEI 1 and RAMIN KHAKSAR 2 1 Department of Seafood Science and Technology, Faculty of Marine Sciences, Tarbiat Modares University, Noor, Iran 2 Department of Food Science and Technology, National Nutrition & Food Technology Research Institute, Faculty of Nutrition Sciences & Food Technology, Shahid Beheshti University of Medical Sciences, No.46, West Argavan, P.O.Box:19395-4741, Shahrak-E- Gharb, Tehran, Iran 3 Corresponding author. TEL: +9821-22376426; FAX: +9821-22360660; EMAIL: hedayat@sbmu.ac.ir Accepted for Publication May 22, 2012 doi:10.1111/j.1745-4549.2012.00765.x ABSTRACT This study was carried out to evaluate the quality of whole gutted fresh rainbow trout via two methods: the immersion of whole gutted rainbow trout in a shallot extract and the immersion of live fish in a shallot extract before being gutted and vacuum packed and stored at 4  1C. The control and the treated fish samples were periodically analyzed for microbiological (total viable count, psychrotrophic count, Enterobacteriaceae), chemical (peroxide value, thiobarbituric acid) and sensory characteristics. The results indicated that immersion of fish in shallot extract increased shelf life of fish stored at refrigeration temperatures. PRACTICAL APPLICATIONS Shallot extract is a natural antioxidant. It can improve the quality of food prod- ucts during refrigerated storage because of the presence of sulfur-containing com- pounds and polyphenolic derivatives in its composition. Shallot extract promotes health by preventing lipid oxidation, and has been shown to possess antibacterial characteristics. In the food industry, it can be used as alternatives to the synthetic antioxidants because the use of these types of antioxidants is controlled because of concern for their carcinogenic potential. INTRODUCTION Fish is a valuable source of protein for human consump- tion. The significance of long-chain polyunsaturated fatty acids (PUFAs) of the n-3 family has gained attention because of their preventive effect against human cardiovas- cular diseases (Sallam 2007). However, given that the shelf life of refrigerated fish is relatively short and that there is a growing tendency of consumers to eat fresh rather than processed or frozen foods, research on the application of new preservation methods and technologies that extend the shelf life of fresh fish is required. Plant extracts are regarded as natural preservatives and their use in foods meets the current demands of consumers for mildly processed or natural products (Atrea et al. 2009). Many spices and herbs, and their extracts, possess antimicrobial activity, although questions still remain regarding their safe use in food products. Plant extracts and their constituents have a wide spectrum of antimicrobial actions. The composition and structure, as well as the functional groups of the extracts, play an important role in determining their antimicrobial activity. Usually, compounds with phenolic groups are the most effective (Ojagh et al. 2010b). Among these, extracts of cinnamon, thyme, shallot, clove, turmeric, rosemary and vanillin have been found to be the most effective against microorganisms. Because of the effect of the direct addition of plant extracts to food, the sensory characteristics of added food may have supplementary applications in food packaging (Seydim and Sarikus 2006; Ojagh et al. 2010a). In fact, the hurdle method (defined by Leistner [2000] as an intelligent combination of hurdles) can be cause to increase shelf life storage. Many studies have evaluated the antimi- crobial and antioxidant activities of several plant extracts, including rosemary (Cadun et al. 2008), oregano (Atrea et al. 2009), thyme (Kykkidou et al. 2009), cinnamon (Ojagh et al. 2010a) and creosote bush (Mendez et al. 2011). In these studies, fish fillets were exposed to plant extracts and the results demonstrated both antimicrobial and Journal of Food Processing and Preservation ISSN 1745-4549 1 Journal of Food Processing and Preservation •• (2012) ••–•• © 2012 Wiley Periodicals, Inc.