Judul: Physical, Chemical. Microbiological Quality of Buffalo Milk Curd from Bukittinggi and Isolation of Lactic Acid Bacteria
Abstrak: Dadih adalah produk fermentasi susu kerbau tradisional dalam tabung bambu dari Sumatera Barat. Proses fermentasi dilakukan oleh Bakteri Asam Laktat (BAL) yang secara alami terdapat pada susu kerbau. Penelitian ini bertujuan untuk mengevaluasi kualitas fisik, kimia dadih dan mikrobiologi serta mengisolasi bakteri asam laktat dari dadih susu kerbau asal Bukittinggi Sumatera Barat. Dari penelitian yang telah dilakukan didapatkan hasil pada uji nilai pH, aktivitas air (aw), kadar air, dan kadar protein menunjukkan bahwa dadih susu kerbau asal Bukittinggi tidak berpengaruh nyata (P>0,05). Data penelitian menunjukkan bahwa dadih susu kerbau berpengaruh nyata (P<0,05) terhadap peubah kadar lemak, kadar abu, total BAL, total E.coli, dan total mikroba yang dihasilkan. Hasil identifikasi menunjukkan bahwa dadih susu kerbau asal Bukittinggi yang di dapat berupa Gram positif berbentuk basil dan kokus, homofermentatif, dan katalase negatif., Dadih is a traditional fermented product of buffalo milk in a bamboo tube from West Sumatra. The fermentation process is carried out by lactic acid bacteria (LAB) naturally present in buffalo milk. This study aims to evaluate the physicochemical quality and microbiology and isolate LAB from dadih. From the research that has been done, the results on the pH, water activity test (aw), water content, and protein content show that the curd from Bukittinggi buffalo milk has no significant effect (P> 0.05). The research data showed that the curd of buffalo milk had a significant effect (P<0.05) on the variables of fat content, ash content, total LAB, total E.coli, and total microbes. The results of the identification showed that the curd from buffalo milk from Bukittinggi which was obtained was gram-positive in the form of bacilli and cocci, homofermentative, and catalase negative.
Keyword: bacteria, buffalo, curd, lactic, milk

Judul: Pengaruh Penambahan Bahan Tambahan Pangan (BTP) yang Dikombinasikan dengan Bakteri Asam Laktat (BAL) terhadap Karakteristik Dadih Susu Sapi
Abstrak: A decrease in productivity of buffalo milk leads us to seek the other solutions to change it as raw material of dadih. Productivity of cow's milk which abundant makes it potential as an alternative to buffalo milk. The different characteristics, both physically and chemically between them causes the characteristic of dadih is also different. Fortification the food additives that combined with lactic acid bacteria in cow's milk, is expected to improve the characteristics of dadih. The purpose of this study was to determine the best combination of the use of food additives and lactic acid bacteria ,which can produce dadih with good characteristics. Based on the results of test determining the best concentration of cow's milk as raw material for dadih so cow’s milk need be evaporated until 50% (v / v). The best concentration of food additives is 100 ppm for enzyme papain, the enzyme renin 2 ppm, and crude enzyme extract of Mucor sp. 0.5 ppm. Analysis of physical, chemical, and microbiological showed that the best treatment is the enzyme renin 2 ppm in combination with 3% Lactobacillus casei. Dadih from this treatments has a viscosity 2278 cP; pH 5,63; total acid value 0,56%; water content 75,03%; protein content 6,80%; fat content 3,35%; carbohydrate content of 13,21%;and total BAL 6,90 x 1010 cfu / gram. The results also showed that all treatments produced dadih with total BAL > 1010 cfu/gram, so that these dadih can classified as a probiotic food. Hedonic test showed that the addition of the enzyme renin 2 ppm and 3% Lactobacillus casei has advantages in terms of taste (3,24), aroma (3,20), texture (3,60), and public acceptance (3,32). As for the color parameters, the treatment was scored still quite high (3,48).
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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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