Storage of Kiwano (Horned Melon) fruits

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The African horned melon (Cucumis metuliferus), also known as horned cucumber, kiwano and melano) is a cucurbit fruit with an yellow-orange exterior with thick blunt spines and a green, gelatinous pulp embedding the many seeds. It is endemic to semi-arid Africa (Bruecher, 1977; National Research Council, 2008). It is a specialty fresh produce item in the U.S. and is considered a “new crop plant” (Benzioni et al., 1993).

For marketing in the U.S, desirable characteristics for kiwanos include a size of about 250 g, a uniform yellow-orange exterior color, and a well developed and flavorful pulp. They are packed in single layer trays with shredded paper to protect the blunt spines. Postharvest losses due to spine punctures are common and the fruit are typically repacked during distribution. The pulp has a mild sweet-acid flavor, but the fruit often have a poor, insipid flavor. For the kiwano to have an adequate flavor, the fruit need to be harvested after the initiation of ripening or color change. The fruit’s main attraction in the U.S. market is its unique external appearance and color.

The stage of maturity at harvest is considered critical for an adequate eating quality and postharvest shelf-life ( Mendlinger et al., 1992). Sugars rapidly accumulate in the fruit during the last 10 days of development and ripening. The kiwano is very chilling sensitive. Fruit stored at 12°C or lower suffered high losses within 30 days. Fruits were stored for 3 months at 20 and 24°C with 30% and 0% decay, respectively (Benzioni et al., 1993). Growers in California store the fruit in buildings at ambient conditions and hope to achieve up to 6 months shelf-life. The kiwano responds to ethylene, and a postharvest treatment of ethylene just before marketing can improve the external color (Benzioni et al., 1993).

The objective of this study was to verify the storage temperatures and benefits of ethylene for California produced kiwano fruits.

Marita Cantwell
UC Davis Department of Food Science and Technology