Removal of Cyanides from Gadung (Dioscorea hispida Dennst.) Tuber Chips using Leaching and Steaming Techniques

Gadung (Dioscorea hispida Dennst.) has been considered as one of staple foods in Indonesia. However, its high cyanides content has limited its utilisation for commercial food production. This work is aimed to investigate the removal of cyanides content from gadung tuber chips through two consecutive treatments, i.e. leaching and steaming and to propose mathematics model for the leaching process. The results showed that processing water flow rate and leaching time affected the efficiency of cyanides removal in the leaching process. The proposed mathematical model was able to represent the removal of cyanides through leaching process very well. The cyanides content removal was also found to be affected by steaming time. Best processing condition was at leaching using 5.00 10-5 m3.s-1 for 3,600 s, followed by steaming for 3,600 s to obtain cyanides content of 29.9 mgkg-1. While the yielded gadung tuber chips are considered as safe for consumption, further research on physicochemical characteristic of the gadung tuber flour is necessary for its utilisation consideration

Penurunan Sianida dalam Umbi Gadung dengan Proses Leaching yang Bekerja Batch

Yam is a tuber plant usually grown in tropical area. The starch contained is potential to be developed as food material like flour as a substitute for wheat in bread making. Although yam tubers were found to have high amount protein and amino acid, they also contained some antinutritional components like cyanogen substances, which can be toxic for human. Cyanogens substances were reduced by batch leaching process which used water as a leaching agent. Yam tuber was sliced into small chips and placed inside the leaching column. Later, 3 L per minute water was flown to the heap of yam chips. The changes of cyanogens content in the tuber chips were analyzed and, presented as HCN equivalent in mg per kg fresh sample every 0.5 hour. After the process, the cyanide content in the yam tuber decreased to an average of 24 ppm at solvent-to-solid ratio from 15 to 40 l/kg and leaching time 2.5 hours