Judul: Kejadian Clostridium petfringens pada Daging Sapi yang Dijual di Beberapa Pasar Swalayan di Kota Bogor
Abstrak: Penelitian ini bertujuan untuk mengetahui kejadian Clostridium perfringens pada daging sapi yang dijual di pasar swalayan di Kota Bogor. C. perfringens merupakaan bakteri patogen penyebab penyakit asal makanan. Penelitian ini menggunakan sembilan sampel daging yang diperoleh dari tiga pasar swalayan. Sampel daging diberi perlakuan non heat shock dan heat shock pada suhu 75 °C selama 15 menit dalam penangas air untuk mengaktifkan spora. Koloni hitam yang tumbuh pada egg yolk-free tryptose sulphite cyclosenne agar (EY-free TSC) setelah 44-48 jam inkubasi pada suhu 37 °C dalam anaerobic jar diidentifikasikan sebagai presumtif positif C. perfringens, selanjutnya dikonfirmasi dengan menggunakan motility nitrate dan lactose gelatine media. Hasil pengamatan menunjukkan 88,9% sampel daging presumtif positif C. perfringens dan 51,47% merupakan C. perfringens tipe A Spora tidak terdeteksi pada sampel daging. Populasi presumtif sel vegetatif C. perfringens pada daging bagian depan karkas, daging bagian belakang karkas, dan daging giling adalah 0,89±0,84 loQ10 coloni forming unit (CFU)/gram, 1,63±1,09 I0Q10 CFU/gram, dan 1,43±0,51 log10 CFU/gram. Sebaran populasi presumtif sel vegetatif C. perfringens di ketiga pasar swalayan adalah 1,00±0,00 10910 CFU/gram di pasar swalayan A, 1,63±1,48 log10 CFU/gram di pasar swalayan B, dan 1,33±0,34 log10 CFU/gram di pasar swalayan C. Populasi tersebut berada diatas ambang batas maksimum kontaminasi Clostridium spp. pada daging yang ditetapkan Standar Nasional Indonesia (SNI) No. 01-6366-2000 yaitu 0 (nol) CFU/gram.
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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: 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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