Judul: Penggunaan Belimbing Wuluh untuk Menghambat Oksidasi dan Mempertahankan Mutu Organoleptik pada Dendeng Sapi Selama Penyimpanan
Abstrak: Meat and meat products have a large amount of fat which can be oxidized easily during storage. Lipid oxidation causes off flavours, change of colour, rancidity, decreasing of nutritional contents and so on. The prevention of lipid oxidation can be done by utilization of antioxidants. Averrhoa bilimbi L. potentially used as natural antioxidant in meat and meat products. This research was conducted to study the influence of utilization of Averrhoa bilimbi L. as natural antioxidant to the qualities, antioxidant activities, and sensory acceptance of dendeng during storage. This research used factorial randomized completely design (RCD) 3x2 with 3 repetition. The first factor was the utilization of Averrhoa bilimbi L. that consisting of A0 (meat seasoning without added Averrhoa bilimbi L.); A1 (meat seasoning after soaking in Averrhoa bilimbi L. juice); A2 (meat seasoning with simultant addition of Averrhoa bilimbi L.). The second factor was the storage treatment after drying that consisting of B0 (without storage) and B1 (4 weeks of storage on room temperature). The result of this research showed that utilization of Averrhoa bilimbi L. had significant effect to the qualities, antioxidant activities, and organoleptics quality of dendeng. Dendeng which meat seasoning without added Averrhoa bilimbi L had no significant effect of moisture content, fat content and TBARS value with others. Dendeng which meat seasoning after soaking in Averrhoa bilimbi L. juice had the better means of activity water and percentage scavenging activity DPPH. Dendeng which meat seasoning with simultant addition of Averrhoa bilimbi L. had the better means of rendemen, peroxide value, phenolic content, color change of dendeng and the mold growth activity. Dendeng which meat seasoning with simultant addition of Averrhoa bilimbi L. bring in better qualities of dendeng.
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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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