Judul: Mutu Mikrobiologi dan Organoleptik Daging Sapi Panggang dengan Penambahan Kecombrang dan Waktu Marinasi 1 atau 12 Jam
Abstrak: Daging sapi panggang memerlukan upaya pada proses pengolahannya sehingga dapat meminimalkan kerusakan akibat mikroba dan mempunyai aspek sensorik yang dapat diterima oleh masyarakat. Penelitian ini bertujuan mempelajari pengaruh formula bumbu yang diberi penambahan kecombrang dengan marinasi jangka singkat atau panjang terhadap sifat mikrobiologi dan organoleptik daging sapi panggang. Rancangan yang digunakan dalam penelitian ini adalah rancangan acak kelompok (RAK) pola faktorial 3 x 2 dengan 3 kelompok periode pembuatan. Faktor pertama adalah penggunaan formula bumbu marinasi (tanpa bumbu, bumbu tanpa penambahan kecombrang, atau bumbu dengan penambahan kecombrang). Faktor kedua adalah lama marinasi (1 atau 12 jam). Hasil penelitian menunjukkan bahwa penambahan kecombrang pada bumbu marinasi tidak berpengaruh nyata terhadap mutu mikrobiologi namun berpengaruh nyata terhadap mutu organoleptik daging sapi panggang pada atribut warna dan rasa. Lama marinasi diantara 1 jam dan 12 jam pada daging sapi tidak berbeda secara signifikan terhadap mutu sensori maupun penghambatan pada pertumbuhan mikroba pada daging sapi panggang. Sebagai kesimpulan, marinasi selama 1 jam efektif dilakukan untuk bumbu tanpa maupun dengan penambahan kecombrang berdasarkan pertimbangan efisiensi waktu marinasi dalam pembuatan daging sapi panggang., Grilled beef requires proper processing method to minimize damaged caused by microorganisms and have sensory aspects that are acceptable by society. This study aimed to investigate the effects of marinade seasoning formula with the addition of torch ginger and short term or long term marination period on the microbiological and sensory properties of grilled beef. This study used randomized block design with a 3 x 2 factorial pattern and 3 groups of producing period. The first factor was the use of marinade formula (without marinade, marinade without torch ginger, marinade with adding torch ginger). The second factor was the length of marinating time (1 or 12 hours). The results showed that the addition of torch ginger in the marinade seasoning did not have a significant effect on the microbiological characteristics but had a significant effect on the sensory properties of grilled beef in terms of color and taste attributes. The marinating time between 1 hour and 12 hours on beef did not have a significant effect on sensory characteristics or inhibition of microbe growth in grilled beef. In conclusion, 1 hour marinating period was effective for both seasoning without or with torch ginger based on considerations of marinating time efficiency in the production of grilled beef.
Keyword: grilled beef, marinade, marinating time, torch ginger

Judul: Microbiological and Organoleptic Properties of Grilled Shortplate Beef with Different Seasoning Formulation and Short Marination Time
Abstrak: The development of marination methods is one of the ways that serves to reduce bacterial content and maintain the quality of beef. This study aims to analyze the influence of adding torch ginger (kecombrang) to the marinade with different short marination times on the microbiological and organoleptic properties of roasted beef. The study used a 3x2 factorial randomized block design. The first factor was different beef marinade spices, namely: without spices, marination without torch ginger, and marination with the addition of torch ginger. The second factor was the marination time, either 30 or 60 minutes. The results of the microbiological test showed that adding marinade spices with or without torch ginger did not significantly differ. However, the organoleptic test indicated that there was an increased preference of the panelists for color, aroma, taste, tenderness, and overall appearance with all marination times (p<0.05). The addition of torch ginger did not affect the microbiological properties of roasted beef but did influence the organoleptic properties of roasted beef in all short marination times., Pengembangan metode marinasi merupakan salah satu cara yang berfungsi untuk mengurangi kandungan bakteri dan menjaga kualitas daging sapi. Penelitian ini bertujuan menganalisis pengaruh penambahan kecombrang pada bumbu dengan lama waktu marinasi singkat yang berbeda terhadap sifat mikrobiologi dan organoleptik daging sapi panggang. Penelitian ini menggunakan rancangan acak kelompok faktorial 3x2. Faktor pertama adalah bumbu marinasi daging yang berbeda, yaitu: tanpa bumbu, marinasi tanpa kecombrang, dan marinasi dengan penambahan kecombrang. Faktor kedua adalah lama waktu marinasi yaitu: 30 atau 60 menit. Hasil uji mikrobiologi menunjukkan bahwa penambahan bumbu marinasi tanpa kecombrang atau dengan kecombrang tidak berbeda nyata. Namun, pada uji organoleptik menunjukkan bahwa terdapat peningkatan kesukaan panelis terhadap warna, aroma, rasa, keempukan, dan penampilan umum dengan semua waktu marinasi (p<0,05). Penambahan kecombrang tidak berpengaruh pada sifat mikrobiologis daging sapi panggang, namun berpengaruh pada sifat organoleptik daging sapi panggang pada semua waktu marinasi singkat.
Keyword: grilled beef, marinades, microbiological properties, organoleptic properties

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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