Provided are: a diketopiperazine mixture suitable for mixing in food and beverages； and a method for producing same. By means of high-temperature, high-pressure processing of plant-based peptides in a liquid, it is possible to produce a plant extract containing a high concentration of diketopiperazine containing cycloleucyl phenylalanine and cycloleucyl leucine. By means of the present invention, diketopiperazine is obtained, which is superior in terms of plant-based natural-substance-derived flavor, and by being added as-is to food and beverages, it is possible to produce food and beverages to which the functionality of diketopiperazine has been added.
