Judul: Physical and Organoleptic Properties of Probiotic Yogurt With The Addition of Red Fruit (Pandanus conoideous L.).
Abstrak: Yogurt can be made from homogenized milk, low-fat milk or skimmed milk with the addition of powdered milk. Starter culture commonly used in yogurt is Lactobacillus bulgaricus and Streptococcus thermophillus can not survive in environments with high acidity, so probiotics needed. One of the fruits that can be used in the process of making yogurt is red fruit (Pandanus Conoideus L). The observed physical characteristics consist of pH, viscosity, total acid concentration and water activity (aw) and organoleptic arachnids observed consisting of color, flavour, aroma and consistency. This research using a complete randomized design (RAL. The results showed that the addition of red fruit has a real effect (P<0.05) on pH, viscosity and total acid titrated and organoleptic test shows the addition of red fruit has a noticeable effect on color, flavour, aroma and viscosity in hedonic quality tests, then in hedonic tests affect aroma and flavour. Based on the results of yogurt testing with the addition of 2.5% this is the closest to control and acceptable to indonesian national standards (SNI)., Yogurt dapat dibuat dari susu yang telah dihomogenisasi, susu berkadar lemak rendah atau susu skim dengan penambahan susu bubuk. Kultur starter yang biasa digunakan dalam yogurt yaitu Lactobacillus bulgaricus dan Streptococcus thermophillus tidak dapat bertahan pada lingkungan dengan keasaman yang tinggi, sehingga diperlukan probiotik. Salah satu buah yang dapat ditambahkan adalah buah merah (Pandanus Conoideus L). Karakteristik fisik yang diamati terdiri atas pH, viskositas, total asam tertitrasi dan aktivitas air (aw) serta karakteristik organoleptik yang diamati terdiri atas warna, flavour, aroma dan kekentalan. Penelitian dilakukan dengan menggunakan rancangan acak lengkap (RAL). Hasil penelitian menunjukan bahwa penambahan buah merah berpengaruh nyata (P<0,05) terhadap pH, viskositas dan total asam tertitrasi. Uji organoleptik memperlihatkan penambahan buah merah berpengaruh nyata terhadap warna, flavour, aroma dan kekentalan pada uji mutu hedonik, lalu pada uji hedonik berpengaruh pada aroma dan flavour. Berdasarkan hasil pengujian yogurt dengan penambahan 2,5% ini yang paling mendekati dengan kontrol dan memenuhi standar nasional Indonesia (SNI).
Keyword: yogurt, red fruit, probiotic, characteristic physic, characteristic organoleptic

Judul: Chemical Properties and Total Lactic Acid Bacteria of Probiotik Yogurt with Addition of Red Fruit (Pandanus conoideus L.)
Abstrak: Produk susu fermentasi yang menggunakan bakteri Lactobacillus bulgaricus and Streptococcus thermophilus dan atau bakteri asam laktat lain disebut yogurt. Penambahan probiotik pada yogurt dapat membantu memperbaiki proses pencernaan. Buah merah memiliki kandungan senyawa antioksidan dan karotenoid. Penelitian ini bertujuan menganalisis sifat kimia dan total bakteri asam laktat yogurt probiotik dengan penambahan buah merah. Persentase buah merah yang ditambahkan ke dalam yogurt yaitu 0%, 2,5%, dan 5%. Pengujian yang dilakukan pada penelitian ini, yaitu uji sifat kimia meliputi kadar lemak, protein, air, abu, nilai pH, keasaman tertitrasi, serta uji total bakteri asam laktat. Analisis data yang digunakan adalah Rancangan Acak lengkap, dengan tiga kali ulangan. Hasil dari penelitian ini menunjukkan bahwa penambahan ekstrak buah merah ke dalam yogurt probiotik dengan persentase yang berbeda berpengaruh nyata (P<0,05) pada pH dan keasaman tertitrasi. Seluruh yogurt P0, P1, P2 menunjukkan nilai mikrobiologi yang sesuai sebagai minuman probiotik. Yogurt P1 dengan penambahan 2,5% ekstrak buah merah menjadi produk terbaik yang sesuai dengan mutu SNI., Fermented milk products that use Lactobacillus bulgaricus and Streptococcus thermophilus bacteria and or other lactic acid bacteria called yoghurt. The addition of probiotic to yoghurt can improve the digestive process. Red fruit contains antioxidants and carotenoids. This study aims to analyze the chemical properties and total lactic acid bacteria of probiotic yoghurt with addition of red fruit extract. The percentages of red fruit added to yoghurt is 0%, 2,5%, and 5%. The analysis carried out in this study was chemical analysis including the content of fat, protein, water, ash, pH value, titrated acidity, and total lactic acid bacteria. Data analysis used was Completely Randomized Design with three repetitions. The result of this research indicated that the addition of red fruit extract into probiotic yoghurt with different percentages had a significant effect (P<0,05) on pH and titrated acidity. All yoghurts P0, P1, P2 showed appropriate microbiological value as probiotic drinks. Yoghurt P1 with the addition of 2,5% red fruit extract is the best product according to the Indonesian National Standard.
Keyword: hemical properties, lactic acid bacteria, probiotic, red fruit, yoghurt

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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