Judul: Isolasi Salmonella Spp. Pada Sampel Daging Sapi Di Wilayah Bogor Serta Uji Ketahanannya Terhadap Proses Pendinginan Dan Pembekuan
Abstrak: Nowadays people must be aware to their choose of food, due to many case affected by salmonella contamination. This research focusing on level of salmonella contamination in beef samples and its survival ability at frozen (-16°C) and refrigeration (6°C) temperature. Beef samples (ground and cut) was collected from 5 traditional market and 10 modern market in Bogor area. The contamination level was determined by aerobic plate count method and conventional isolation of Salmonella spp. The average of aerobic plate count from traditional market was 7.49 ± 0.49 log CFU/g and from modern market was 6.09 ± 0.85 log CFU/g. Meanwhile, the isolation level of Salmonella spp. with API 20E from total 30 samples reach 16.67%. One sample was indicated 99.9% (excellent identification) of Salmonella spp. while the other 4 samples was indicated 89.4% (excellent identification). Salmonella spp. in beef samples kept at -16°C and 6°C show that it was good to survive in both temperature, no matter first inoculum in 3 log CFU/g or 6 log CFU/g. Its survival ability can be seen from insignificant change of total Salmonella spp. counted (p>0,05).
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Judul: Kombinasi iradiasi dan penyimpanan pada suhu beku terhadap kandungan bakteri pada daging sapi asal rumah potong hewan di kabupaten serta kota Bogor
Abstrak: Beef contains nutrients such as protein and water content is so high that suitable media for microbial growth. The presence of microbial can degrade beef’s quality. Therefore it needs to do some efforts to slow the damage by microbes on the beef with frozen storage and use of irradiation technology. This study on the effect of frozen storage and irradiation of the content of bacteria in beef. Also performed to determine the concentration of protein and water, and identification of Salmonella. Meat samples taken from three Slaughter Houses (RPH) in the District and the City of Bogor. Storage carried out for 4 weeks in the freezer with irradiation doses of 0, 3 and 5 kGy. The results showed levels of protein in meat slaughterhouses A, B and C were irradiated with 0 kGy dose at week 0, respectively 67.95%, 61.13% and 70.40%, while the water content of beef slaughterhouses A, B and C, each for 75.31%, 74.26% and 73.91%. No Salmonella obtained from three samples of beef. In general, the dose of 3 kGy could eliminate the total aerobic bacteria, coliform, Escherichia coli and Staphylococcus spp. that meet the SNI (2008) in all three samples of beef and looks significantly different to that are not irradiated (p <0.05). Combination treatment of frozen storage with irradiation provides a real impact on reducing the total count of aerobic bacteria, coliform, Escherichia coli and Staphylococcus spp
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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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