Judul: Kajian Aktivitas Antimikroba Ekstrak Belalang terhadap Bakteri E. coli dan S. aureus serta aplikasinya pada bakso daging
Abstrak: Javanese grasshopper (Vangala nigricornis) is one of various insects that grows in Indonesia. Beside to its nature is destructive and considered crop pests for farmers, Javanese grasshopper used as food for some people, particularly in Wonosari Jogjakarta. In addition to the useful as food, Javanese Grasshoppers also capable of inhibiting the growth of pathogenic bacterias, that are E. coli and S. aureus. The aim of this research was to find out the Javanese grasshopper as a preservative in fact, meat products. Research prefixed to prove the existence of the antimicrobial activity from Javanese grasshopper by using the well diffusion method. Extract derived from four solvents, that were water, ethanol, acetic acid, and hexan. From four extracts was got, extract acetic acid (± 9 mm) and extract ethanol (± 7 mm) that showed antibacterial activity. Next step was to determined the minimum inhibitory concentration of the extract was selected (acetic acid), which amounted to 6 %. The last step was to test to meatball products, from this test known the extracts Javanese grasshopper able to extend the life of stored meatballs than meatballs control.
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Judul: Aplikasi Substrat Antimikroba dari Bakteri Asam Laktat sebagai Biopreservatif pada Bakso Daging dengan Penyimpanan Dingin
Abstrak: Meetball (bakso) is a popular meat product in Indonesia. As other meat products, beef bakso has short shelf life at ambient temperature. The objective of this research were observed the effect of antimicrobial substrat as natural preservative on beef bakso at low temperature., which was isolated from Lactobacillus fermentum 2B4. The complete randomize design two factors was used to analyzed the effect of antimicrobial substrat to physical quality of beef bakso. Beef bakso with antimicrobial substrat 50% at 2 and 4 days preservation showed strong activity in inhibit growth of E. coli populations (P<0.05) Key word: beef, meat ball, substrat antimicrobials, microbiologic quality
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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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