Eddo / Tarro / Colocasia esculenta

Colocasia, met de Nederlandse naam olifantenoor, is een tropische plant uit de familie van Araceae (Aronskelken) waar onder andere ook de Anthurium, Philodendron, Arum, Zantedeschia en Alocasia toe behoren. 
Van oorsprong is dit kruidachtige gewas afkomstig uit de tropische delen van Zuidoost Azië en Polynesië. De knollen of rhizomen van C. esculenta zijn onder andere in Polynesië, maar eigenlijk in een groot deel van de tropen, een zeer belangrijke bron van voedsel en worden vaak aangeboden onder de naam Taro. Ook het blad wordt gegeten. Alle delen van de plant bevatten oxaalzuur en zijn alleen veilig om te eten wanneer ze gekookt worden.

Teelt: In het voorjaar kunnen de knollen opgepot worden in goed doorlaatbare grond op een warme plaats. De watergift dient in het begin beperkt te zijn omdat de rhizomen gevoelig zijn voor rot. Zodra er leven waargenomen wordt kan de watergift duidelijk verhoogd worden; in het algemeen houden Colocasia's van erg veel water. In principe kunnen ze prima in potten gehouden worden maar een plek in de volle grond zal uiteindelijk een veel groter plant opleveren. Zodra er geen kans meer is op nachtvorst kunnen de planten in de volle grond geplaatst worden. Zoals de meeste exoten is een goede waterdoorlaatbare en humusrijke grond ideaal. Veel zon en water zal de groei nog eens extra stimuleren, een oeverplek bij een vijver is vaak perfect. Na het uitplanten zal de groei eerst enige tijd stil vallen maar zodra deze weer op gang komt gaat het hard. De rest van de zomer verlangen de colocasia's, behalve water geven en een keer bijmesten, weinig aandacht.

De tot 4 kg zware wortelknollen zijn wit, grijs of rozig bruin tot blauwpaars van kleur. Ze bevatten tot 25% zetmeel. Het gehalte aan eiwit (3 %) en vitaminen is relatief gering. De knollen worden gekookt, geroosterd, gebakken en gefrituurd. In Afrika worden de knollen soms in een pasta ("fufu") verwerkt. Jonge bladeren en bladstelen kunnen ook worden gegeten. Alle plantendelen bevatten oxaalzuur, wat door verhitting afgebroken wordt. Een populaire snack gemaakt van de taro zijn tarochips

De taro behoort tot de oudste cultuurplanten. In Azië wordt de taro al duizenden jaren verbouwd. De wereldproductie ligt rond de 6 miljoen. Ongeveer de helft daarvan wordt verbouwd in Afrika. In Polynesië is de taro een belangrijk stapelvoedsel.
  • In Bangladesh noemt met het "mukhi kochu", gekookt met kleine garnalen in een dikke kerrie.
  • In China zegt men "yùtou" of "yùnãi".
  • Japanners noemen hem "satoimo" de dorpsaardappel.
  • Arvi Gosht is een populaire gerecht in Noord-India. Taro met lams- of schapenvlees.
  • De Indianen in Suriname noemen de wortel "aroei" en is algemeen bekend als "Chinese Tayer".
  • De nauw verwante soort Xanthosoma is de basis voor de populaire Surinaamse gerecht pom.
  • In Vietnam, waar taro "Khoai Môn" heet, wordt het gebruikt als vulling in loempia's, cakes, puddingen, smoothies, soepen en andere desserts.

Eddoe or Eddo is a tropical vegetable, a variety of Colocasia esculenta, closely related to taro (dasheen), that is primarily used for its thickened stems (corms). It has smaller corms than taro, and in all but the best cultivars there is an acrid taste that requires careful cooking. The young leaves can also be cooked and eaten, but (unlike taro) they have a somewhat acrid taste.
Eddoes appear to have been developed as a crop in China and Japan and introduced from there to the West Indies where they are sometimes called "Chinese eddoes". They grow best in rich loam soil with good drainage, but they can be grown in poorer soil, in drier climates, and in cooler temperatures than taro.
Eddoes are also called malangas in Spanish-speaking areas, but that name is also used for other plants of the Araceae family, including tannia (Xanthosoma spp.). Eddoe is known as arvi or arbi in Urdu and Hindi and kochur mukhi in Bengali in South Asia. And chembb or Chembu in Malayalam.
Eddoes make part of the generic classification cará or inhame of the Portuguese language that, beside taro, also includes root vegetables of the genera Alocasia and Dioscorea. They are the most commonly eaten inhames/carás in the states of São Paulo, Rio de Janeiro and Espírito Santo, as well as surrounding regions of all. They are also fairly common in Northeastern Brazil, where they might be called batata (literally "potato"), but less so than true yams of the genus Colocasia. According to Brazilian folk knowledge, the eddoes most appropriate to be cooked are those that are more deeply pink, or at least pinkish lavender, in the area where the leaves were cut.

Phytother Res. 2005 Sep;19(9):767-71. The anti-cancer effects of poi (Colocasia esculenta) on colonic adenocarcinoma cells In vitro. Brown AC1, Reitzenstein JE, Liu J, Jadus MR.
Hawaiians tend to have lower incidence rates of colorectal cancer and it was hypothesized that this may be due to ethnic differences in diet, specifically, their consumption of poi, a starchy paste made from the taro (Colocasia esulenta L.) plant corm. Soluble extracts of poi were incubated at 100 mg/mL in vitro for antiproliferative activity against the rat YYT colon cancer cell line. (3)H-thymidine incorporation studies were conducted to demonstrate that the poi inhibited the proliferation of these cancer cells in a dose-dependent manner. The greatest suppression of YYT colon cancer growth occurred when 25% concentration was used. When poi was incubated with the YYT cells after 2 days, the YYT cells underwent apoptotic changes as evidenced by a positive terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) stain. Poi enhanced the proliferation of normal mouse splenocyte control cells, suggesting that poi is not simply toxic to all cells but even has a positive immunostimulatory role. By flow cytometry, T cells (CD4+ and CD8+) were predominantly activated by the poi. Although numerous factors can contribute to the risk of colon cancer, perhaps poi consumption may contribute to the lower colon cancer rates among Hawaiians by two distinct mechanisms. First, by inducing apoptosis within colon cancer cells; second, by non-specifically activating lymphocytes, which in turn can lyse cancerous cells. Our results suggest for the first time that poi may have novel tumor specific anti-cancer activities and future research is suggested with animal studies and human clinical trials.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3769987/ Breast cancer mortality is primarily due to the occurrence of metastatic disease. We have identified a novel potential therapeutic agent derived from an edible root of the plant Colocasia esculenta, commonly known as taro, that has demonstrable activity in a preclinical model of metastatic breast cancer and that should have minimal toxicity. We have shown for the first time that a water-soluble extract of taro (TE) potently inhibits lung colonizing ability as well as spontaneous metastasis from mammary gland-implanted tumors, in a murine model of highly metastatic ER, PR and Her-2/neu negative breast cancer. TE modestly inhibits proliferation of some, but not all, breast and prostate cancer cell lines. Morphologic changes including cell rounding were observed. Tumor cell migration was completely blocked by TE. TE treatment also inhibited prostaglandin E2 (PGE2) synthesis and downregulated cyclooxygenase (COX) 1 and 2 mRNA expression. We purified the active compound(s) to near homogeneity with antimetastatic activity comparable to stock TE. The active compound with a native size of approximately 25 kD contains two fragments of nearly equal size. The N-terminal amino acid sequencing of both fragments reveals that the active compound is highly related to three taro proteins; 12 kD storage protein, tarin and lectin. All are similar in terms of amino acid sequence, post-translational processing and all contain a carbohydrate-binding domain. This is the first report describing a compound(s) derived from taro, that potently and specifically inhibits tumor metastasis.

Iran J Pharm Res. 2012 Spring; 11(2): 621–634.Antihypertensive and Diuretic Effects of the Aqueous Extract of Colocasia esculenta Linn. Leaves in Experimental Paradigms. Otari Kishor Vasant,a Bhalsing Gaurav Vijay,a Shete Rajkumar Virbhadrappa,a,* Nandgude Tanaji Dilip,a Mali Vishal Ramahari,b and Bodhankar Subhash Laxamanraob
Colocasia esculenta Linn (CE) is traditionally used for the treatment of various ailments such as high blood pressure, rheumatic pain, pulmonary congestion, etc. Hence in present study, the effect of aqueous extract of CE leaves (AECE) was evaluated for antihypertensive and acute diuretic activity in rats.
Preliminary phytochemical evaluation revealed the presence of carbohydrate, saponins, tannins, and flavonoids in AECE. The animals did not show any sign of toxicity and mortality after the administration of AECE 2000 mg/Kg in acute oral toxicity study. The administration of AECE (100, 200, and 400 mg/Kg/day, p.o.) for six weeks and AECE (10, 20, and 40 mg/Kg, IV) on the day of experiment in renal artery-occluded hypertensive rats and AECE (20 and 40 mg/Kg, IV) in noradrenalin-induced hypertension in rats produced significant (p < 0.05) anti-hypertensive effects. AECE (400 mg/Kg, p.o.) showed positive diuretic activity at 5 h. AECE (200 and 400 mg/Kg, p.o.) significantly increased sodium and chloride content of urine in 5 h and 24 h and additionally potassium in 24 h urine.
Hence, the results of the present study revealed the antihypertensive and weak diuretic activity of AECE. These effects may be attributed due to the ACE inhibitory, vasodilatory, β-blocking, and/ or Ca2+ channel blocking activities, which were reported for the phytoconstitunts, specifically flavonoids such as vitexin, isovitexin, orientin, and isoorientin present in the leaves of CE.