| dc.description.abstract | Elephant foot yam (Amorphophallus oncophyllus) as tuber crops which grows wildly at subtropical and tropical forest in Indonesia, apparently is one of the potential exports commodity. The export of this yam tubers to Japan is usually in the form of chips or flour, which then processed to be a kind of traditional food, “shirataki” noodle and “konyakku” tofu. Elephant foot yam tubers can be purified into a glucomannan flour that has special characteristics. The special characteristics of glucomannan flour among other hydrocolloid is its capability to form thick solution in water, swell by a high swelling power, form gel, form thin film in sodium hydroxide solution or form impermeable thin layer with glycerin. It also has a melting characteristics like agar-agar, so it can be used for microbial growth media. In industry, glucomannan is used as raw material of paper, textile and glue, celluloid material, blasting material, foodstuff, cosmetics and cleaner. The conventional method for preparation of glucomannan flour is by mechanical, like sieving, blowing, and polishing. High purified glucomannan flour is produced by separating starch from yam flour. This study has done in other approach that the utilization of α-amylase as starch digesting enzyme will release the starch from cell glucomannan so it resulted to the high purified glucomanna. This research will examine the effects of t temperature (65 oC, 80 oC, and 95 oC) and enzyme dose (1 Unit/g flour, 2 Unit/ g flour dan 3 Unit/ g flour) to the characteristics of glucomannan flours. The result from preliminary research showed that carbohydrate is the main components in fresh tuber and flour. The α-amylase shows the highest activity in pH 5 and has activity on 1.764,71 U/ml, 3.363,29 U/ml and 13.545,75 U/ml for temperature 65 oC, 80 oC, and 95 oC, respectively Starch content in glucomannan flour after α–amylolysis declined from 10.63 % to 4.76 - 0.40 %, while glucomannan content increased from 28.75 % to 42.35 - 80.53 %. The value of whiteness degree changed from 21.26 % of glucomannan flour before hydrolysis into 19.48 % until 28.37 %. The viscosity of glucomannan declined from 16,833.33 cPs to 1500 - 3925 cPs. The water absorption capability of glucomannan flour changed from 1464.75 % to 1288.78 – 1696.29 %. Bulk density of glucomannan flour before hydrolysis is 741.65 kg/m3 then changed to 641.48 - 776.01 kg/m3 after hydrolysis. Value of pH flour glucomannan before and after hydrolysis had changed from pH 6.58 to around pH 4.90 - 5.21. Hydrolysis temperature, enzyme dose treatment and interaction both of them obviously influenced to the starch content, glucomannan content, and whiteness degree of flour, while the yield and viscosity are only influenced by temperature (p<0,05). Glucomannan flour after hydrolysis and extracted by using ethanol 95 % gives high glucomannan content but has lower value of viscosity. The best treatment for preparing the glucomannan flour by α–amylolysis can be obtained from 65 oC of hydrolysis temperature, 3 U/g flour of enzyme dose for 30 minutes | en |
