Oca: Colorful Tubers from the Andean Highlands.
Oxalis tuberosa
Synonyms— Oxalis crenata; Oxalis Ockas; Surelle tubereuse.
Family — Oxalidaceae (Woodsorrel family)
Family Characteristics — Oxalidaceae family members tend to be small with shamrock-type leaves with flowers parts occurring in multiples of five [6].
Aliases — kao, New Zealand yam, Peruvian potato, oca, oxalis, sorrel (ENGLISH); apiña, apilla, kawi (AYAMARA); truffette acide {meaning: acid truffle}(FRENCH); Knollen-Sauerklee {meaning: sorrel tubers} (GERMAN); ok’a, okka, oqa, (QUECHUA); ciuba, cubio, ciuva, chullco, huisisai, ibia, ibias, oca, orcas, papa colorada, papa extrajera, papa roja, quiba, ruba, timbo (SPANISH).
Binomial Etymology—Oxalis, from GREEK, is a term generally referring to “sorrel;” tuberosa, from ancient LATIN, is a term for knobs or swellings. It can be gleaned that the binomial simply refers to “a tuber-bearing sorrel.”
Binomial Pronunciation: — ok-suh-lis too-bur-OH-zuh
When considering an ancient staple food that produces attractive and glossy tubers in a vast array of wild colors with— sometimes— twice the productivity of the potato [3], one is temped to wonder: “why is the oca not grown the world over?”
There are so many oca varieties exhibiting flavor characteristics ranging from sour to fruity-sweet with colors ranging from cherry red to canary yellow.
Sure, this native to the Andes of central Peru and northern Bolivia has gained traction as a profitable crop of agriculture in New Zealand and Mexico, but, aside from those areas, nobody else seems to be growing these en masse. Surely, there are reasons for that. Right?
Welcome to the colorful and ancient Andean world of Oxalis tuberosa!
Oca Culinary Uses
It is said that oca roots are so varied in flavor among varieties that some are sour, some are insipid, and some are sweet enough to be sold among fruits [3].
Therefore—unlike potatoes— oca tubers are known to be amenable to both savory and sweet preparations; they can be eaten raw with lemon, salt and pepper, boiled, steamed or baked like potatoes, preserved in vinegar, or even candied [3].
According to the Chinchero (indigenous community in southern Peru), oca tubers are said to naturally attain a degree of sweetness when sun-dried for two or more days according to personal taste [1][2]. If the dried tuber is then frozen, it is termed, khaya; if it is washed after freezing yielding a whiter color, it is known as okhaya [1]. Okhaya is traditionally ground into flour for porridges and desserts of various kinds [1].
Of course, as with any starch producing edible product known to man, oca tubers can be fermented to produce alcoholic beverages [3].
Oca Ethnobotany
Second only to the potato, oca was/is widely consumed and cultivated among indigenous high altitude tribes residing in Argentina, Bolivia, Peru, and Venezuela as a staple food [3].
From 1777 to 1788, the Spanish botanist, Don Hipolito Ruiz, collected notes on the ethnobotanical uses of plants by local inhabitants of Peru and Chile. This treasure trove of adventure writing and information would not be translated and published for another 164 years under the name: Ruiz Relación Histórica del Viage que Hizo a los Reynos del Perú y Chile el Botánico Hipolito Ruiz en el Año de 1777 hasta el de 1788 [4].
In Ruiz’s “Relación,” it was conveyed that the leaves and stems of the oca plant were used to bring down high fevers, namely, those associated with Typhoid fever; the tubers were crushed into a POULTICE and applied to swellings brought on by mumps or goiters. Relación also mentioned that oca was also used to treat sore throat, painful urination, jaundice, and choking [4].
Why is Oca Not Grown Everywhere?
There have been several mentioned limitations to widespread cultivation of this crop.
Daylength Sensitivity
While day length-insensitive cultivars are available in Mexico and New Zealand, the oca crop is known to be daylength sensitive, meaning, they will only produce tubers under day length conditions encountered in their native lands [3]. See: photoperiodism. Additionally, importing oca tubers from Mexico or New Zealand may be problematic depending on your country’s bureaucratic agricultural screening processes.
Socioeconomic Prejudice
Locally, in the Andean regions, oca has a reputation for being a “poor person’s food” [3]. This leads to unwillingness to cultivate a crop in a region hosting the highest biodiversity of oca variants on Earth.
For Fear of Oxalates
Neverminding the fact that oca tubers most often contain less oxalic acid (a substance associated with causing kidney stones) than spinach and sometimes even potato, oca—and sorrels in general— will forever be associated with the substance through their genus nomenclature: Oxalis [3]. After hearing my brother suffering with kidney stones, however, I have a certain empathy for these fears no matter how unwarranted.
Kidney stones?! WHAT? Get those things away from me!
Oca Bioactive Constituents
The recently isolated main storage protein in Oxalis tuberosa, ocatin, has been found to inhibit the growth of an array of phytopathogenic bacterium [5].
Oca Videos
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With Love,
Kevin.
