Judul: Sifat Fisikokimia, Organoleptik dan Aktivitas Antioksidan Dendeng Daging Ayam dengan Penambahan Serbuk Bunga Rosella
Abstrak: Dendeng berpotensi mengalami reaksi oksidasi yang dapat dihambat dengan antioksidan. Senyawa antioksidan banyak terkandung dalam bahan alami, seperti bunga rosella. Penelitian ini bertujuan untuk menguji sifat fisikokimia, organoleptik dan aktivitas antioksidan dendeng daging ayam dengan penambahan serbuk bunga rosella. Variabel yang diukur dalam penelitian ini meliputi nilai pH, aw, kadar air, aktivitas penghambatan terhadap 2,2-difenil-1-pikrilhidrazil (DPPH), kapasitas antioksidan, nilai TBARS, dan sifat organoleptik (warna, aroma, tekstur, dan rasa) dendeng daging ayam. Rancangan yang digunakan dalam penelitian ini adalah rancangan acak lengkap (RAL) dengan tingkat penambahan serbuk bunga rosella yang berbeda (0%; 0,15%; 0,30%). Hasil penelitian menunjukkan bahwa penambahan serbuk bunga rosella berpengaruh nyata (p<0,05) terhadap nilai pH yang semakin menurun, serta nilai aw dan kadar air yang semakin meningkat. Penambahan serbuk bunga rosella tidak berpengaruh nyata terhadap nilai TBARS, aktivitas penghambatan DPPH dan kapasitas antioksidan. Secara keseluruhan dendeng daging ayam dengan penambahan serbuk bunga rosella pada taraf 0,15% dan 0,30% tidak memberikan pengaruh terhadap sifat fisikokimia, organoleptik, dan aktivitas antioksidan., Jerky has the potential to undergo oxidation reactions that can be inhibited by antioxidants. Many antioxidant compounds are contained in natural ingredients, such as rosella flowers. This study aimed to examine the physicochemical, organoleptic, and antioxidant activity of chicken meat jerky with the addition of roselle flower powder. The variables measured in this study included pH value, aw, moisture content, inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), antioxidant capacity, TBARS value, and organoleptic properties (color, aroma, texture, and taste) of chicken meat. The jerky design used in this study was a completely randomized design (CRD) with different levels of rosella flower powder addition (0%; 0.15%; 0.30%). The results showed that the addition of rosella flower powder had a significant effect (p<0.05) on the decreasing pH value and increasing water content. The addition of rosella flower powder did not significantly affect the TBARS value, DPPH inhibitory activity and antioxidant capacity. Overall chicken jerky with the addition of rosella flower powder at the level of 0.15% and 0.30% did not affect the physicochemical, organoleptic, and antioxidant activity properties.
Keyword: antioxsidant, meat chicken jerky, physicochemical sensory, rosella flowers, sensory properties

Judul: Sifat Fisikokimia, Organoleptik dan Aktivitas Antioksidan Dendeng Sapi dengan Penambahan Jahe Merah (Zingiber officinale Var. Rubrum) Segar
Abstrak: Dendeng merupakan produk olahan daging yang dapat mengalami ketengikan akibat reaksi peroksidasi lipid. Ketengikan dapat dicegah dengan penggunaan antioksidan, seperti jahe merah. Penelitian ini bertujuan menguji sifat fisikokimia, organoleptik dan aktivitas antioksidan dendeng sapi yang diberi penambahan jahe merah segar dengan konsentrasi sebanyak 0%, 10% dan 20% berdasarkan berat daging. Sampel dendeng yang diuji organoleptik berupa dendeng mentah dan matang. Pengujian sifat fisikokimia dan aktivitas antioksidan menggunakan dendeng yang mentah. Hasil penelitian menunjukkan bahwa penambahan jahe merah segar terhadap dendeng sapi berpengaruh nyata (P<0,05) terhadap nilai pH, aw, kadar air dendeng sapi, dan karakteristik organoleptik pada atribut rasa, aroma dan kelenturan dendeng sapi mentah dan matang. Penambahan jahe merah segar tidak berpengaruh nyata pada nilai TBARS dan aktivitas antioksidan. Secara keseluruhan, dendeng sapi dengan penambahan jahe merah segar sebesar 10% menunjukkan hasil terbaik untuk pengujian sifat fisikokimia, organoleptik dan aktivitas antioksidan., Jerky or dendeng is a processed meat product that can have rancidity due to lipid peroxidation reactions. Rancidity can be prevented by using antioxidants such as red ginger. This study aims to examine the physicochemical, sensory properties and antioxidant activity of beef jerky with the addition of fresh red ginger with proportion 0%, 10% and 20% based on beef weight. The sample that used for sensory evaluation were raw and cooked dendeng. Physicochemical properties as well as antioxidant activity measurement used raw dendeng. The addition of fresh red ginger to dendeng had a significant effect (P<0,05) on pH value, water activity dan sensory properties of taste, flavor and flexibility attribute. The addition of fresh red ginger to dendeng had no significant effect on TBARS value and antioxidant activity. Overall, beef jerky with the addition of 10% fresh red ginger showed the best results for physicochemical, sensory properties and antioxidant activity measurement.
Keyword: antioxidant, beef jerky, fresh red ginger, organoleptics

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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