1). Physical-morphological properties
Have you ever seen a gadung tuber? Currently these types of tubers are rather difficult to find. In Indonesia, this plant has a name like bitule (Gorontalo), gadu (Bima), gadung (Bali, Java, Madura, Sunda) iwi (Sumba), ax (Sasak), Salapa (Bugis) and sikapa (Makassar). Umbrella elliptical bulb with sides that are almost parallel or widened against the peak, while the extent narrows around the base. Umbi gadung that is ripe brown or brownish yellow, fluffy with a length of about 5-6 cm.
Picture Umbi and Gadung plants
Umbi gadung can be grouped based on the color of the meat tubers, namely white gadung and yellow gadung. Examples of white gadung are gadung correct, lime gadung, white gadung, gadung punk, and arintil gadung. Examples of yellow rhinoceros are turmeric and rice gadung. Gadung arintil is a type of gadung that has the most number of bulbs in each gob. Thick one tuber bulbs ranging from 7 – 15 cm and diameter 15 – 25 cm, with a very sharp bulb fiber. Yellow yellow is generally larger and denser than white gadung. The color of the outer shell is grayish white with yellow tuber meat. The outer arintil skin outline is brownish and the color of white umbilical.
Transverse wedge slices almost the same structure with potatoes.
2). Chemical Properties
Umbi gadung contains carbohydrates, fats, crude fiber and lower ash compared with cassava. Water content and protein gadung gadung higher than cassava. Umbi gadung contains phosphor (P2O5) as much as 0.09%, calcium (CaO) 0.07 &, iron (Fe2O3) 0.003%. The chemical composition of the gadung tubers can be seen in Table 2.13.
Table 2.13. Chemical composition of gadung tubers
Umbrian tubers contain alkaloid dioscorin which is toxic and dioscorin which is non-toxic. Alkaloids are also found in other dioscorea. Besides the gadung bulb also contains a number of saponins, mostly in the form of a poisonous dioscin. Bulbs are left old color will turn green and toxic levels will increase.
The effect of gadung poisoning at first felt uncomfortable in the throat, dizziness, then vomiting blood, felt choked and exhausted. Usually to reduce or eliminate the toxins contained in the gadung tubers, done by mixing the ashes into the tuber gadung that has been sliced, let for a while, washed and ready to be processed.