Ume (scientific name: Prunus mume Sieb. et Zucc) is often mistaken for plum (scientific name: Prunus somestica L), which is in the same group of Rosaceae Prunus, however, they have very different characteristics. Ume contains 4--5% acidity compared to 1--2% acidity in plums. As ume fruit ripens, citrus acid occupies a higher ratio than other organic acids. The fruit and skin of ume contains polyphenol and the fruit contains amino- acids. Our studies indicate that GABA might be produced from glutamine acid.