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: Physicochemical Properties and Antioxidant Activity of Grilled Beef with the Additional of Kecombrang and Different Marination Duration
Abstrak: Penelitian ini bertujuan menganalisis pengaruh penambahan bunga kecombrang pada bumbu dan waktu marinasi yang berbeda terhadap sifat fisikokimia (kadar air, aw, pH) dan aktivitas antioksidan daging sapi panggang. Penelitian ini menggunakan daging sapi bagian shortplate yang diiris dengan ketebalan 3,5 cm. Daging sapi panggang sebelumnya dimarinasi dengan bumbu tanpa kecombrang, atau bumbu yang ditambah kecombrang selama 30 atau 60 menit. Sebagai kontrol digunakan daging yang tanpa marinasi. Hasil penelitian menunjukkan bahwa penggunaan bumbu marinasi, baik dengan ataupun tanpa penambahan bunga kecombrang nyata menurunkan pH (p<0,05) dan meningkatkan aktivitas penghambatan terhadap DPPH serta kapasitas antioksidan (p<0,05) dibanding kontrol. Tidak ada perbedaan pH dan aktivitas antioksidan pada daging sapi yang dimarinasi dengan bumbu tanpa ataupun dengan penambahan bunga kecombrang. Tidak ada perbedaan antara lama marinasi 30 ataupun 60 menit pada semua peubah. Kesimpulannya adalah bahwa untuk efisiensi waktu, marinasi selama 30 menit menggunakan bumbu, baik tanpa maupun dengan penambahan bunga kecombrang merupakan lama marinasi terbaik untuk diaplikasikan., The aim of this study was to analyze the effect of kecombrang flowers addition to seasonings and different marination duration on physicochemical properties (moisture content, aw, pH) and antioxidant activity of grilled beef. This study used beef shortplate sliced with a thickness of 3.5 cm. The grilled beef is previously marinated using seasoning without or with kecombrang flowers for 30 or 60 mins. As a control, unmarinated meat was used. The results showed that the use of marinade, either with or without the addition of kecombrang flowers significantly reduced the pH (p<0.05) and increased the DPPH scavenging activity and antioxidant capacity (p<0.05) compared to the control. There was no difference in pH and antioxidant activity in marinated beef using seasonings with or without kecombrang flower addition. There was no difference between 30 or 60 mins marinations duration on all variables. The conclusion is that for time efficiency, marinating for 30 mins using seasoning, with or without kecombrang flower addition is the best marination duration to apply.
Keyword: antioxidant activity, grilled beef, marinade, marination duration, physicochemical 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.
Keyword: