Фіолетовий ямс

Yam is the common name for some plant species in the genus Dioscorea, family Dioscoreaceae, that form edible tubers. Sweet potatoes, which belong to the morning glory family, Convolvulaceae, are distant from actual yams, which are monocots in the order Dioscoreales. The name ube is derived from Tagalog in the Philippines, while uwhi derives from Māori in New Zealand.

Origin and Cultivation

Its origins are in the Asian and Oceanian tropics. Dioscorea alata was first cultivated in Southeast Asia, and it is one of the most important staple crops in Austronesian cultures. The Philippines shows the highest phenotypic diversity of ube, making it one of the likely centers of origin of ube domestication. Remains of ube have been recovered from the Ille Cave archaeological site in Barangay New Ibajay, El Nido, Palawan (c. 11,000 BP).

D. alata was carried along with the Austronesian migrations as a canoe plant, from Island Southeast Asia as far as Madagascar and Polynesia. Although not grown in the same quantities as the African yams, it has the largest distribution worldwide of any cultivated yam. Purple yam remains an important crop in Southeast Asia, particularly in the Philippines. It also remains important in Melanesia, where it is grown for ceremonial purposes tied to the size of the tubers at harvest time.

Chemistry

The color of purple varieties is due to various anthocyanin pigments. In two Thai accessions of purple yam, the anthocyanins had a cyanidin or peonidin nucleus. Alatanin C, a cyanidin glycoside, was the main anthocyanin in both accessions.

The tubers of those two accessions held 70 g starch and 25-30 g amylose per 100 g on a dried weight basis, depending on the accession and the age of the vine. D. alata has relatively high levels of oxalates (486-781 mg/100 g dry matter), which are associated with antinutritional effects and kidney stone formation.

Uses

Purple yam is most common in Philippine cuisine, where it is known as ube or ubi. It is widely applied for many Philippine desserts, such as ube cake, ube cheesecake and ube crinkles. It is often eaten boiled, baked, or as a sweetened dessert called ube halayá. The violet cultivars, in particular, turn dishes distinctively vivid violet because of the high amount of anthocyanins. Purple yams have edible tubers with a mildly sweet, earthy, and nutty taste, reminiscent of sweet potatoes or taro. Purple yams are also valued for the starch that can be processed from them. Ube halaya is made from peeled and boiled ube, which is grated and mashed. The mashed yam is added, with condensed milk (originally sweetened coconut milk) and added sugar, to a saucepan of melted butter or margarine, and the mixture is stirred until thickened.

Although available as a dietary supplement and used in folk medicine, no clinical evidence shows that D. alata has any therapeutic properties.