Journal of Middle East Applied Science and Technology (JMEAST) ISSN (Online): 2305-0225 Issue 18(2), August 2014, pp. 501-504 501 Abstract— Marine products form an important source of nutrients which are extensively used in human diets. Shrimp, a rich source of polyunsaturated acids and protein at a high percentage, is one the most important marine products. Green tea on the other hand contains a large quantity of antibacterial and antioxidant compounds which have been used to reduce putrescence in foodstuff. This research investigated the effect of various doses of green tea extract (200, 400, and 600 ppm) on the total bacterial load, psychrotopic and lactic acid bacteria and compared the results from the various doses because of the importance of the nutritional and economic value of shrimp. The results indicated that green tea extracts can increase shelflife between 2 to 5 days depending on the treatment type and extend the products use by date. In general the results indicated that different doses of green tea cause the increase in bacterial parameters in shrimp during refrigeration and the 600ppm is recommended as the best dose. Keywords— bacterial load, green tea (Camellia Sinensis) extracts, quality, shrimp. a Department of Food Science and Technology, Sabzevar Branch, Islamic Azad University , Sabzevar, Iran b Young Researchers and Elite Club, Sabzevar Branch, Islamic Azad University, Sabzevar, Iran (corresponding author: Tel: +98-937-4342212, Fax: +98-571-2647513 ; Postal code: 9618814711, E-mail address: Mohammadh.kamani@gmail.com). c Department of Fishery, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran. I. INTRODUCTION ARINE products play a significant role in food supply of the people of the world. The increase in demand for seafood as a valuable source of nutrients in recent years has resulted in the growth and development of the fishing industry, extraction of marine products, and remarkable progress in the fishing industry of most states containing coastlines near seas, gulfs, and open waters. Shrimp farming can be considered one of the most important industries in this area (Ojifard et al, 2000). Shrimp is one of the products enjoying a high consumption rates in the southern beaches of Iran especially Boushehr. These products are susceptible to putrescence because of their rich source of polyunsaturated acids and high protein content and preservation in unsuitable conditions can thereforecause the meat to putrefy and loose its quality. Undesirable changes in texture, colour, and aroma are some of the most important adverse changes that can occur (Nirmal and Benjakul, 2001). Cinnamon extract coating (Ojagh et al, 2012); rosemary extract (Etemadi et al, 2008), and thyme (Hamzeh&Rezaei, 2011) are some of the many measures taken to delay bacterial putrescence in the meat of the aquatic animals. Green tea, whose antioxidant qualities are well-known, is one of the most recognised plant extract. For example the use of Tea polyphenols as an antioxidant in packaged mackerel under the Cololabissairavaccum was investigated and its effect on delaying the chemical and oxidization changes resulting in the extension of the shelf-life of the fish confirmed (Rezaei et al, 2011). Green tea leaves contain 36% of the polyphenols according to dry weight. Catechinsare the dominant group among polyphenols in tea and have been identified as the effective antioxidants countering oxygen radicals and bonding metallic ions (Ojagh et al, 2005)., This research aims to investigate the effect of the various doses of green tea extract on the magnitude of the bacterial parameters during refrigeration because of the importance of the nutritional and economic value of the shrimp and the benefits of green tea. II. MATERIALS AND METHODS Sample Preparation The samples were washed in cold water and grouped following purchase and transportation to the laboratory. They were then treated with 200, 400, 600 ppm extracts and were refrigerated together with a placebo sample for 15 days, and tested on 0, 5, 10, and 15 day periods. The effect of Green tea on bacterial changes in white shrimp (LithopenaeusVannamei) refrigerated at a temperature of 4 ± 1 °C Mohammad Mehdi Fereahtian a , Mohammad Hassan Kamani b *, Masoud Shafafi Zenoozian a , Sadegh Rigi a , Omid Safari c . M