| 摘要 |
The present invention aims to provide extracts or beverages containing 2,5-piperazinedione,3,6-bis(phenylmethyl)-,(3S,6S)—, which is a useful substance with an improving effect on learning motivation, in an easy-to-ingest form and at a high concentration. Extracts or beverages whose ratio between the content of 2,5-piperazinedione,3,6-bis(phenyl-methyl)-,(3S,6S)— (unit: μg/100 g) and Brix(Bx) is 6 (μg/100 g)/Bx or more can be ingested continuously over a long period of time as foods and beverages useful for improvement of learning motivation. |
