Ikeda is msg was a huge commercial success but some scientists did not believe umami was really a fifth taste they continued to believe that there were only four tastes then,in 2000, almost 100 year after lkeda's discovery scientists found physical proof the human tongue contains tiny receptors or taste buds which allow us to tell the difference between tastes scientists found that these receptors responded to glutamate in a special way in fact they found that the receptors responded in that way only to glutamate and not to any of the other four tastes