Judul: Pengaruh penambahan ekstrak etanol cengkeh (Eugenia caryophyllata Thunb) dalam sosis untuk penghambatan kerusakan oksidatif lemak
Abstrak: Oksidasi lemak merupakan penyebab utama kerusakan pada daging dan produk olahan daging. Sosis adalah produk olahan daging yang sudah cukup populer. Sosis mudah mengalami kerusakan oksidatif yang dapat menyebabkan ketengikan. Antioksidan sintetis seperti BHA dan BHT sering ditambahkan pada sosis untuk menghambat terjadinya oksidasi lemak. Namun karena kecenderungan saat ini untuk menggunakan bahan tambahan alami, sehingga penggunaan rempah-rempah sebagai salah satu bahan alami yang mengandung senyawa antioksidan semakin mendapat perhatian. Penelitian ini bertujuan untuk mengetahui pengaruh penambahan ekstrak etanol cengkeh dalam menghambat oksidasi lemak pada sosis sapi dan sosis ayam selama penyimpanan. Perlakuan yang diukur adalah penambahan ekstrak etanol cengkeh pada beberapa konsentrasi (200, 500 dan 800 ppm) dan kontrol (tanpa penambahan ekstrak etanol cengkeh) serta perlakuan lama penyimpanan. Penyimpanan sosis dilakukan pada suhu dingin (4oC) dan suhu beku (-10oC). Aktivitas antioksidan dari ekstrak etanol cengkeh diukur sebelum diaplikasikan pada sosis.
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Judul: Pengaruh Penambahan Ekstrak Etanol Cengkeh (Eugenia caryophyllata Thunb) dalam Sosis untuk Penghambatan Kerusakan Oksidatif Lemak
Abstrak: Lipid oxidation is responsible to the deterioration of meat and meat products. Sausages are popular processed meats which are easy to experience rancid. The addition of naturally occured antioxidant in spices might be possible to reduce the rancidity in meat products. The effect of ethanol clove extract addition at different concentrations (0, 200, 500 and 800 ppm) to inhibit the lipid oxidation of beef and chicken sausages were studied. The treated sausages were stored at chilling temperature of 4oC for 14 days as weel as at freezing temperature of -10oC for 56 days. Antioxidant activity of ethanol extract of clove were measured before its application to sausages. Lipid oxidation (peroxide and TBA value), fatty acid profile, and microbial growth were determined during the storage period. The result showed that ethanol extract of clove had better antioxidant activity than that of BHT (IC50 of ethanol extract of clove was 33 μg/ml, lower than BHT that was 65 μg/ml). All concentrations significantly reduced (p<0.05) the peroxide and TBA values of sausage compared to the control. Sausage with the addition of 800 ppm showed the lowest lipid oxidation and was sensorically acceptable. Combination of ethanol extract of clove and freezing temperature was more effective than combination of etanol extract of clove storing at chilling temperatur.
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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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