Judul: Produksi Pati Ganyong (Canna edulis Kerr) Resisten Tipe IV melalui Modifikasi Asetilasi
Abstrak: Edible canna is a potential forest product that can be used as food diversification. The objective of this research was to obtain resistant starch which has been proven for its physiological effect. The production of resistant starch was done by chemically modified which used different concentration of acetic anhydride, namely 3, 4, and 5% in 300 g of edible canna. Two types of edible canna used in this research are red edible canna and white edible canna. The degree of substitution which gained through acetylation is 0.082, 0.168, 0.257 for red edible canna and 0.082, 0.168, 0.257 for white edible canna. Through proximate analysis, modification of edible canna starch resulted in increase of water content and decrease of ash content, while protein content, lipid and carbohydrate content showed no relatively difference. Total starch content, amylose, amylopectin, dietary fiber, resistant starch and digestibility of starch were measured for edible canna and the selected modified edible canna (4%). The results showed that modification through acetylation can increase resistant starch content. It increased 3.54% in red edible canna while for white edible canna is 3.80%. These results influenced the increasing of total dietary fiber with value 2.45% for red edible canna and 1.95% for white edible canna. The increasing of dietary fiber will result in the decreasing of digestibility of starch with value 1.58% for red edible canna and 1.98% for white edible canna.
Keyword: starch modification, resistant starch type IV, digestibility, Canna edulis

Judul: Time and Temperature Effects of Ultrasound Treatments on the Resistant Starch Content of Canna edulis Ker
Abstrak: Ultrasonication was applied to Ganyong (Canna edulis Ker) starch for three treatment of times (15, 30, and 45 minutes) at controlled temperature (30⁰, 45⁰, and 60⁰C). Ganyong as a local indigenous plant was chosen as the material in this study because it has big potential to produce resistant starch from its high content of amylose compared to other tuber’s starch, such as cassava, sweet potato, yam and arrowroot. Ultrasonication at 60⁰C and 45 minute was chosen as best treatment combination in this study due to the highest yield of resistant starch produced. Native canna starch was observed to have 1.45±0.24 % of resistant starch, however the number significantly increased to 48.19 ± 0.84% of resistant starch after modification (p<0.05). Further physicochemical changes of native and modified starch were observed. The results showed that there were no significant changes in the proximate analysis profiles before and after treatment. However, the ultrasonication significantly influence the pasting profiles (p<0.05) which was also expected due to the increase of starch granule size range from 30-160 μm to 45-179 μm after modification. The morphological changes were clearly observed by SEM and PLM, which showed swollen granule with rougher surface and fissures after modification. Thermal analysis using DSC did not significantly influenced the gelatinization temperature of the granule starch, however the increase of enthalpy (ΔH) occured from 2.99 to 10.86 J/kg. This result indicated the increase of resistant starch within canna starch granule.
Keyword: ganyong, Canna edulis Ker., resistant starch, ultrasonication

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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