Judul: Pertumbuhan Total Mikroba Keju Ricotta yang Dibuat Menggunakan Jenis Asam yang Berbeda pada Penyimpanan Suhu Rendah
Abstrak: Keju ricotta merupakan keju lunak tanpa proses pemeraman yang berasal dari Italia. Keju ricotta dibuat dari koagulasi susu atau whey dengan asam. Tujuan penelitian ini yaitu menganalisis pertumbuhan total mikroba keju ricotta dengan perhitungan Total Plate Count, dan respon panelis terhadap keju ricotta yang disimpan pada suhu rendah dengan pemberian jenis asam yang berbeda. Analisis data dilakukan dengan metode rancangan percobaan Rancangan Acak Kelompok (RAK) dengan 5 perlakuan jenis asam dan 3 kelompok. Hasil yang berbeda nyata selanjutnya diuji dengan uji Tukey. Hasil penelitian menunjukkan pertumbuhan mikroba pada keju ricotta tidak berbeda antar perlakuan. Respon panelis menunjukkan panelis menyukai keju ricotta dengan rasa yang tidak masam, tidak beraroma susu, berwarna putih hingga putih kekuningan. Panelis menyukai keju ricotta dengan tekstur yang lembut maupun keras. Simpulan dari penelitian ini yaitu perbedaaan perlakuan jenis asam pada keju ricotta tidak memengaruhi pertumbuhan total mikroba serta jumlah koloni mikroba pada keju ricotta sudah memenuhi standar.
Keyword: analisis sensori, keju ricotta, mikroba, total plate count

Judul: Karakteristik keju lunak hasil fermentasi dengan bakteri asam laktat indigenus
Abstrak: Milk with a high fat and protein content can be used in cheese production. Initially, cheese products in Indonesia are imported for supply the specific consumer. However, the cheese has become a kind of common food for Indonesian people. Cheese is usually consumed as a supplement and a flavor enhancer of food. This growing triggers some dairy-based food industry in Indonesia to produce cheese and its diversification. The diversifications are ranging from fresh to processed cheese. One of innovation product is the probiotic cheese products. This study used three different types of lactic acid bacteria: 1) Lactobacillus acidophilus RRM-01 (LA-RRM01), 2) Bifidobacterium longum RRM-01 (BL-RRM01) and 3) Lactococcus lactis DSB 42 (LL-DSB42) to produce a functional cheese product by fermentation of lactic acid bacteria. Analysis was performed on the quality of fresh milk using a pH meter and milko tester, bacterial culture are prepared by refreshment and propagation, soft cheese production by the addition lactic acid bacteria cultures. The analysis of the products includes physical (yield), chemical (pH, moisture content, protein rude, crude fat and ash) and microbiological (lactic acid bacteria). The research used the factorial completely randomized design in three replication. The parameters are pH value, carbohydrate, LAB population. Analysis of crude protein, crude fat, moisture content were performed by randomized block design (RBD). The data were collected from seven treatments of lactic acid bacteria culture (LA-RRM-01/LA, BL-RRM-01/BL, LL-DSB 42/LL, BL-LA, BL-LL, LA-LL and BL-LA-LL). The data were analyzed by analysis of variance (ANOVA) and followed by Duncan test for multiplication comparison test. The Sensory analysis was tested by non-parametric analysis. Fresh milk quality of FH cows with a fat content (4.9%), protein (3.8%), lactose (4.0%) and pH (6.7) is accordance with the SNI 314.1:2011 standard. The cheese was produced contain the yield ranging from 17.9% -22.5%, pH values from 5.10 to 5.79, and classified as soft cheese. The treatment did not effect in moisture content, crude protein and ash, but there were significant differences (P <0.05) in the carbohydrate and crude fat either in single culture or culture of the three bacteria. The use of single culture bacteria or in a mixture did not inhibit the other cultures. The population of lactic acid bacteria in the products is approximately 9 log10 cfu g-1. The hardness product cultured by mixed two bacterial cultures were significantly different (P <0.05) with that of three bacterial cultures. Fifty panelists gave neutral and like slightly assessment for the color, flavor, aroma and general preferences of soft cheese (value 3.6 to 5.3), dislike slightly for the appearance of texture (value 2.5 to 3.6). Panelists assessment of the hedonic quality were white-yellow (value 5.0 to 6.1), bitter-sour taste typical cheese-(value 4.4 to 5.0), the typical cheese-sour aroma (value 5.3 -5.6), texture (value 5.2 to 6.4) and consistency (value 5.3 to 7.1). Because of high water content in all the soft cheese products (> 55%) and looks watery consistency, the texture of the products is less preferred by the panelists. Panelists felt bitter and sour after taste. It was concluded that the milk used for cheese production meets
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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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