A new strategy to protect Katsura-uri (Japan's heirloom pickling melon, Cucumis melo var. conomon) from extinction

Background: Katsura-uri (Cucumis melo var. conomon), an heirloom vegetable cultivated in Kyoto, Japan is at the risk of extinction. Japanese food culture has traditionally used immature and midripened fruit in the preparation of pickles, the consumer demand of which has markedly decreased. A new strategy was adopted for Katsura-uri, aimed at increasing its inclusion in the present diet habit (e.g., Katsura-uri juice as a functional drink to prevent obesity and diabetes). Methods: Chemical analysis was performed to determine sugar profiles of fully ripened Katsura-uri fruits that uniquely possess muskmelon-like fragrance. In the questionnaire-based sensory evaluation, palatability was compared among the fruit juices without sweeteners and those with sugar or zero-calorie sweetener. Results: Chemical analysis results showed that the fully ripened Katsura-uri fruit had significantly lower levels of fructose, glucose, and sucrose (low-calories and lack of sweetness) than muskmelon fruits. In the questionnaire-based sensory evaluation, zero-calorie sweetener dramatically improved the palatability of the unprocessed fruit juice without altering its low-calorie properties and muskmelon-like fragrance. Conclusion: This demonstrated a new strategy to protect this heirloom vegetable from extinction by adding a new function that could increase its demand as a low-calorie fruit in the present diet habit for human health