Judul: Chemical Properties and Total of Lactic Acid Bacteria of Cow’s Milk Kefir with Addition of Red Fruit Extract  (Pandanus Conoideus Lam).
Abstrak: Kefir merupakan produk susu fermentasi yang menggunakan bakteri asam laktat dan ragi. Susu sapi dipilih karena susu sapi merupakan zat pelengkap yang kaya akan nutrisi seperti protein, lemak, vitamin, mineral dan karbohidrat. Buah merah berfungsi sebagai aditif dalam makanan untuk meningkatkan nilai gizi, dan bekerja sebagai antimikroba. Penelitian ini bertujuan menguji sifat kimiawi dan total bakteri asam laktat pada kefir susu sapi dengan penambahan buah merah. Penambahan buah merah sebesar 0%, 2,5% dan 5% dari total ekstrak buah merah dalam pembuatan kefir. Rancangan analisis statistik yang diujikan adalah rancangan acak lengkap (RAL) dengan perlakuan penambahan ekstrak buah merah pada konsentrasi yang berbeda dengan tiga kali ulangan yaitu pertama tanpa penambahan buah merah atau kefir 100% sebagai kontrol; penambahan kedua ekstrak buah merah 2,5%; penambahan ketiga ekstrak buah merah 5%. Hasil menunjukkan bahwa perbedaan persentase penambahan ekstrak buah merah pada formula kefir susu sapi tidak berpengaruh nyata (P>0.05) terhadap semua analisis kimia dan total bakteri asam laktat kecuali pada total asam tertitrasi berpengaruh nyata (P<0.05)., Kefir is a fermented milk product that uses lactic acid bacteria and yeast. Cow milk is the most prefereable raw material for kefir production due to its high nutrition content including protein, fat, vitamins, minerals and carbohydrates. Red fruit functions as an additive in food to increase nutritional value, and works as an antimicrobial. It leads to an assumption that the use of red fruit might be able to increase the functionality of kefir. The addition of red fruit by 0%, 2.5%, 5% of the total red fruit extract in the manufacture of kefir, the chemical analysis observed was the percentage of total protein, total fat, water content, ash content and total acid titrated. The microbiological analysis observed was the total lactic acid bacteria. The experiment was done under a completely randomized design. The data analysis was done under a one-way ANOVA. The results showed that the difference in the percentage of the addition of red fruit extract to the goat's milk kefir formula had no significant effect (P> 0.05) on all chemical analyzes and the total LAB except for TAT had a significant effect (P <0.05).
Keyword: Buah Merah, Kefir, Susu Sapi

Judul: Physical and Organoleptic Properties of kefir from cow’s milk Supplemented by Red Fruit Extract (Pandanus conoideus)
Abstrak: Kefir susu sapi merupakan produk susu fermentasi menggunakan starter biji kefir yang terdiri dari bakteri asam laktat, kapang, dan khamir. Kefir memiliki manfaat bagi kesehatan karena termasuk dalam pangan probiotik. Kefir juga mengandung eksopolisakarida dan peptida bioaktif yang dapat meningkatkan sistem imun tubuh. Buah merah adalah buah endemik dari Papua yang memiliki manfaat juga bagi kesehatan karena mengandung zat aktif yang dapat meningkatkan sistem imun tubuh. Zat aktif yang terkandung dalam buah merah adalah karotenoid, alfa tokoferol, beta karoten, asam linoleat, asam oleat, asam linolenat, dan asam dekanoat. Tujuan penelitian ini adalah menganalisis sifat fisik dan organoleptik kefir susu sapi dengan penambahan ekstrak buah merah 0%, 2,5% dan 5%. Analisis sifat fisik yang diuji adalah viskositas, nilai pH, nilai aw, dan total asam tertitrasi. Analisis sensori yang dilakukan adalah uji hedonik dan uji mutu hedonik. Hasil penelitian menunjukan penambahan ekstrak buah merah berpengaruh nyata (P < 0,05) terhadap nilai viskositas, total asam tertitrasi, uji hedonik parameter warna, dan aroma serta uji mutu hedonik parameter warna, aroma, dan kekentalan, namun tidak berpengaruh nyata (p > 0,05) terhadap nilai aw, nilai pH, uji hedonik parameter rasa dan kekentalan serta uji mutu hedonik parameter rasa., Cow's milk-based kefir is a fermented milk product that uses kefir grains utulizing of lactic acid bacteria (LAB) and yeast combination as fermentation starter. Kefir is very beneficial for health because it contains probiotic active exopolysaccharides and bioactive peptides that can stimulate the body's immune system. Red fruit (Pandanus conoideus) is an endemic fruit of Papua which had known to have various health benefit effects. Red fruit contains bioactive compounds which can boost the immune system. The compounds include carotenoids, alpha-tocopherol, beta carotene, linoleic acid, oleic acid, linolenic acid, and decanoic acid. This studsy aims to analyze the physical and organoleptic properties of cow's milk-based kefir with the addition of 0%, 2.5%, and 5% red fruit extract. The tested physical properties were viscosity, pH value, aw value, and total titrated acid, coupled with the sensory analysis through hedonic test and the hedonic quality test. The results showed that the addition of red fruit extract had a significant effect (P < 0,05) on the viscosity value, total titrated acid, the hedonic test for color and aroma parameters, and the hedonic quality test for color, aroma, and viscosity parameters, but had no significant effect (p > 0,05) on aw, pH, taste, and viscosity parameter hedonic test, and taste parameter hedonic quality test.
Keyword: Kefir, organoleptic, physical properties, red fruit extract

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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