Judul: Karakterisasi sifat fisikokimia dan fungsional fraksi pati dan tepung umbi lima kultivar uwi (Dioscorea alata)
Abstrak: Yam (Dioscorea alata), as a bulbous plant, was rich in starch content. Yam starch pastes naturally had a character that was resistant to high temperatures, and this character was needed in food processing. A fairly high diversity, quitely high plant productivity and easily in cultivation of yam plant indicated the potential utilisation of yam tuber as raw material in food industry. Starch in food processing applications would result in the final product that was affected by refined starch physicochemical properties. As for food processing, information about the starch physicochemical characteristics was necessary, which was typical characteristic to the type (source) of starch. Physicochemical character was influenced by several factors such as the type (source) of starch, granule size, amylose content and starch crystallization. Starch with different on its granules sizes had different chemical composition that was contribute to the different pasting character and paste viscoelastisity. Pasting characters and paste viscoelastisity themselve were important functional characters of the starch in food processing applications as thickeners. In relation to that and for the development usage of yam tuber, this study was aimed to observe and to study the physicochemical characteristics and functional properties of starch granules and flour particle size fractionation from several yam cultivars, especially in the paste formation and paste viscoelastisity profile. The chemical composition of starch was specific for each yam cultivar which influenced the nature of the starch physical and functional properties. It was found that yam starch had unimoda asymmetrical distribution of its granule size with a higher portion on the large size, and the size ranged 7-100 μm. The morphology of yam starch granules was round disc-shaped, elliptical, oval and round with smooth wavy surfaces. The chemical composition of yam starch had lipid content ranged 16-30 % db, amylose ranged 23.44-26.99 % db and phosphorus ranged 268.15- 365.36 ppm db. Yam starch crystallinity structure had type-B pattern with low crystallinity which was ranged 20.6-30.4 %. Based on the viscoelastisity profile of its cold paste, yam starch had strong resistance to high friction up to =107 rad/s. of the sweep test frequency Fractionation of yam starch was achieved by dry sieving Retsch Siever with 400 and 500 meshes, and was resulted in unperfectly separated of the size fractions. The fractionation was provided a significantly different on average value among the fractions for all cultivars with the range of average of 20.89- 27.93 μm as smaller fraction, 22.41-28.82 μm as medium size fraction and 25.00- 34.80 μm as large size fraction. Based on the average value of the fraction, the larger the granule size contributed to the increase of amylose and phosphorus content and reduced starch crystallinity. The difference in the granule size fraction was not enough to produce any significant effect of size on gelatinization character. In the paste formation, the starches showed type-B profile and higher paste stability could be found in the bigger granule size. The viscoelastisity character showed that the value of storage modulus (G') was increase as the granule size increase which was lead to the stronger gel formation of the paste from small granule
Keyword: yam starch, size fractionation, pasta profile, gelatinization, viscoelastisity

Judul: Kajian Proses Pemurnian Tepung Glukomanan dari Umbi Iles- Iles Kuning (Amorphophallus Oncophyllus) dengan Menggunakan Enzim α-Amilase
Abstrak: 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
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Judul: Portofolio Arbitrase Pada Capital Market Line Dan Security Market Line
Abstrak: sekuritas atan portofolio. Salah satu asumsi yang digunakan dalam model ini adalah tidak diperbolehkan terjadinya arbitrase. Arbitrase adalah tindakan yang memanfaatkan terjadinya perbedaan harga sekuritas P<lda w'.. . ktu yang bersamaan pada dua pasar yang berbeda atau lebih. Ketika tidak diperbolehkan adanya arbitrase, semua investor akan memilih portofolio pasar yaitu portofolio yang terdiri atas semua sekuri(HS yang ada di pasar. Portofolio pasar ini merupakan portofoJio sekurilas berisiko yang oplimaL Portofolio optimal ini jika digambarkan pada SML dan CML akan berada tepat pacta garis-garis tersebut. Faktanyd dalam dunia nyata saa! ini arbitrase dapat terjadi. Apabila arbitrase terjadi maka investor tidak akan memilih portofolio pasar melainkan memilih portofolio arbitrase karena lebih menguntungkan. Portofolio arbitrase ini menguntungkan karena nilai harapan returnnya lebih besar daripada nilai hardpan return portofolio pasar dengan risiko yang
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