Judul: Physical Properties, Organoleptic, and Total Lactic Acid Bacteria of Yogurt with the Addition of Ambon Banana Fruit Puree (Musa paradisiaca L.)
Abstrak: Yoghurt merupakan hasil olahan susu dari fermentasi bakteri asam laktat (BAL) yaitu Streptococcus thermophilus dan Lactobacillus bulgaricus. Buah pisang ambon memiliki rasa yang manis dan kandungan gizi yang tinggi. Penelitian ini bertujuan menganalisis sifat fisik (nilai pH, viskositas, dan total asam tertitrasi), organoleptik (intensitas kecerahan, cita rasa, kekentalan, serta aroma), dan total bakteri asam laktat pada yoghurt dengan penambahan pure buah pisang ambon. Persentase puree buah pisang ambon yang ditambahkan ke yoghurt yaitu 0%, 5%, dan 10%. Rancangan yang digunakan dalam penelitian ini adalah rancangan acak lengkap (RAL) dengan tiga kali ulangan. Hasil penelitian menunjukkan bahwa penambahan buah pisang ambon pada yoghurt berpengaruh nyata (P<0,05) terhadap nilai viskositas dan uji mutu hedonik pada sifat organoleptik yoghurt, tetapi tidak berpengaruh nyata (P>0,05) terhadap nilai pH, total asam tertitrasi (TAT), uji hedonik parameter aroma pada sifat organoleptik yoghurt dan total BAL. Persentase terbaik ditemukan pada perlakuan penambahan buah pisang ambon sebanyak 10%., Yogurt is a dairy product from the fermentation of lactic acid bacteria (LAB), namely Streptococcus thermophilus and Lactobacillus bulgaricus. Ambon banana fruit has a sweet taste and high nutritional content. This study aims to analyze the physical properties (pH value, viscosity, and total titratable acid), organoleptic (intensity of brightness, taste, viscosity, and aroma), and total lactic acid bacteria in yogurt with the addition of ambon banana fruit puree. The percentage of banana puree added to yogurt was 0%, 5%, and 10%. The design used in this study was a complete randomized design (RAL) with three replications. The results showed that the addition of ambon banana fruit to yogurt had a significant effect (P<0,05) on the viscosity value and hedonic quality test on the organoleptic properties of yogurt, but no significant effect (P>0,05) on pH value, total titratable acid (TAT), hedonic test of aroma parameters on the organoleptic properties of yogurt and total LAB. The best percentage was found in treatment of adding 10% ambon banana fruit.
Keyword: lactic acid bacteria, yogurt, ambon banana fruit puree, organoleptic, physical properties

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.
Keyword: