Nationwide distribution of Kyo-yasai (heirloom vegetables in Kyoto) and the advantages of traditional farming methods with importance of ‘Syun’: a case of mizuna

Abstract

Abstract Introduction This study aimed to review the farming activity and the administrative measure to successfully increase the distribution of heirloom vegetable “mizuna” nationwide by examining the paradigm shift in the use of its young less-branched form for salad. We also discussed that breeding programs of the young form ironically resulted in reduction the flavor and the antimutagenicity of this vegetable. Methods Through hearing survey, we explored reasons for the successful nationwide distribution of heirloom vegetable, mizuna. Through chemical analysis, the fragrant ingredients in mizuna, their antimutagenicity and the changes in their amount for one year were determined. Results and discussion The primary factor for commencing the distribution of mizuna includes the new idea of using young less-branched form of mizuna as salad ingredient, which has been recognized by most who were involved in promoting the distribution of mizuna among farmers, distributors, and employees of agricultural extension section at Kyoto Prefecture office. The secondary factor is the fact that the primary factor coincides on a time axis with other two factors: the occurrence of the boom of Kyoto's heirloom vegetables and the Vegetable Management Stabilization Project found as a measure of Kyoto Prefecture. We determined three fragrant compounds in mizuna, 3-butenyl isothiocyanate, 3-phenylpropionitrile, and phenylethyl isothiocyanate, of which their antimutagenic effects were also identified. Those amounts were highest at the best harvest season called ‘Syun’ in the past because of the cold temperature of Japanese winter in traditional open-field cultivation. Conclusion It implied that the successful nationwide distribution of mizuna resulted from the administrative measures based on the paradigm shift in the new use of mizuna for salad due to increase in demand of the vegetable in contemporary dishes. The traditional cultivation of mizuna might be suitable if wishing the flavor and antimutagenicity at the best harvest season ‘Syun’.