Ulluco (Ullucus tuberosus Loz.)

Ulluco (Ullucus tuberosus Loz.) is a traditional staple food crop grown northern Argentina to Venezuela at elevations between 2,400 and 4,200 metres. As one of the "lost crops" used by the Incas it is still grown and eaten today, mainly by subsistence farmers. It is largely unknown outside South America.

In South America ulluco was probably brought into cultivation from the wild in the central Andes of Peru and Bolivia in about 5500 BC. Botanical material from several coastal Peruvian archaeological sites has been identified as containing starch grains, vessels and xylem of ulluco. Illustrations of ulluco have been found on wooden vessels, ceramic urns
and sculptures from the same region, which are dated from about 2,250 - 2,050 BC. The Incas cultivated a wide variety of root crops including ulluco, which became less important as they were forced to grow European vegetables after the Spanish invasion in 1531.

The name ulluco is derived form the Quechua word ulluku. The large number of local names including ulluma, illaco, melloco, papalisas, michur and rubas shows the importance of ulluco in these regions of South America.

Ulluco is a compact, potato-like herbaceous annual crop which produces below ground auxiliary stolons which enlarge to form terminal starchy tubers. The tubers are smooth and spherical with waxy skins, between 2-10 cm across, or curved and elongate, and between 2-15 cm long. A wide range of bright skin colours is produced both between and within cultivars, including white, yellow, orange, red, magenta, or green. Tubers may also be spotted or even candy striped.

In South America ulluco are most often boiled, shredded, grated, mashed, pickled, mixed with hot sauces, or used to thicken soups and stews with meat and other vegetables. They are used in a number of traditional dishes including soups in Ecuador, olluquito con charqui (with meat) in Peru, and ají de papalisas (with peppers) in Bolivia. Contemporary dishes incorporate cooked ulluco tubers in salads, and the leaves are also eaten in soups and salads. Cooked ulluco tubers have been reported as having a smooth texture and a slight earthy taste, and others describe the flavour as mucilaginous and similar to okra. Some cultivars contain mucilage which can be removed by soaking or preboiling before cooking.

Ulluco have recently been introduced into New Zealand from South America and are being evaluated as a potential new addition to the range of vegetables consumed in this country. This tuber has the potential to be popular with New Zealand consumers. Because of the large variety of colours, they could be sold as a mixed blend rather than as a uniform product.

The skin of ulluco tuber is soft and does not need to be peeled before eating. The white to lemon-yellow flesh has a smooth silky texture with a nutty taste. A major appeal of ulluco is its crisp texture, which remains even when cooked. Ulluco tubers are reported to have a long shelf life Some tubers contain high mucilage levels which could be seen as a negative feature because of the resulting gumminess in texture - mucilage is a non-starch polysaccharide so contributes to the total carbohydrate content of the tuber. In South America however ulluco with high mucilage levels are often used to thicken stews. Ulluco tubers with high mucilage content are gummy when raw, but after cooking this characteristic is usually reduced or lost. The mucilage can easily be removed by soaking the tubers in water or parboiling before use.
Ulluco tubers are usually cooked whole and take about the same time as potatoes to cook. However, the use of the microwave may reduce this cooking time.

Sensory evaluation in New Zealand showed that panellists liked the red tubers best. This is in contrast to a study done in Ecuador which showed that consumers preferred the yellow and red tubers. Other researchers who studied ulluco in Peru, Bolivia and northern Argentina also reported that the yellow cultivar was the most popular one eaten from the markets they sample. The commercial success of potato (Solanum tuberosum), sweet potato (Ipomoea batatas) (kumara in New Zealand) and oca (Oxalis tuberosa) in New Zealand suggests that ulluco and other tuber crops may also be grown successfully in New Zealand and could enjoy profitable niches in supermarkets, health food stores and in the restaurant trade as well as for the general public.