In this study,the quality characteristics which include(physicochemical,structural characteristics and sensory evaluation)of beef loin submitted to fast freezing and thawed by five different methods (Refrigerator,Oven,Microwave,tap water and Room temperature)were examined The beef samples were defrosted to the point of reaching a core temperature of 0oC,followed several parameters were examined which include physical characteristics[(drip loss,thawing loos,cooking loss,and water holding capacity(WHC)].In addition to the chemical characteristics[(moisture content,protein solubility,thiobarbituric acid(TBA),myoglobin concentratio (Mb)and met myoglobin formation(Met-Mb)].As well as polyacrylamide gel electrophoresis profile (SDS-PAGE) and sensory evaluation were performed. The findings suggested that, beef sample thawed by tap water revealed lower drip, thawing and cooking loss, also leads to higher moisture content and WHC than the other thawing methods.Moreover, this thawing method(tap water)prevent lipid oxidation by decreased TBA vale and percent of Met-Mb formation as well as increasing Mb.It was also evident from the findings that the thawing techniques influenced the electrophoretic patterns of the beef samples.It was found that the samples with microwave thawing method have a higher band counts and greater intensity,showing higher damage to the proteins of the meat,making fragmentation,structure loss and liberation of small peptides,which affecting the nutritional value and functionality of the meat.However,the data of this experiment have shown that beef sample thawed by tap water protect meat quality and consistency efficiently and will help the meat manufacture and those who consuming the products. It was concluded that the characteristics of meat quality are connected not only to the freezing process, but also to the system and conditions of thawing used.