Judul: Penentuan umur simpan yogurt kacang hijau (Phaeseolus radiatus, Linn)
Abstrak: Kacang hijau termasuk salah satu tanaman pangan yang telah dikenal luas oleh masyarakat, bahkan tanaman yang termasuk dalam keluarga kacang-kacangan ini sudah lama dibudidayakan. Di Indonesia, tanaman kacang hijau merupakan tanaman kacang-kacangan ketiga yang banyak dibudidayakan setelah kedelai dan kacang tanah. Oleh karena kandungan protein yang cukup tinggi dan harganya yang relatif murah, kacang hijau memiliki prospek yang baik sebagai bahan makanan bergizi yang dapat dikonsumsi masyarakat luas, sehingga sangat potensial untuk dikembangkan dalam rangka meningkatkan nilai ekonomisnya. Salah satu alternatif bentuk pengolahannya adalah dengan membuat yogurt dari kacang hijau. Namun umur simpan yogurt yang pendek terkadang menjadi kendala, karena ketidaktahuan konsumen tentang penyimpanan yogurt. Untuk menjamin bahwa yoghurt kacang kedelai masih layak dikonsumsi dan belum mengalami kerusakan, diperlukan informasi tentang umur simpan. Penelitian ini bertujuan untuk mengetahui umur simpan yoghurt kacang hijau dan mengukur penurunan mutu yogurt selama penyimpanan. Penelitian ini dilakukan dengan menyimpan yogurt kacang hijau di dalam tiga suhu berbeda, yaitu 5 oC, 15 oC dan 25 oC. Serta dikemas dalam tiga kemasan berbeda, yaitu botol gelas, HDPE dan PP. Untuk menentukan umur simpan yogurt kacang hijau digunakan metode Extended Storage Studies (ESS) atau metode konvensional yaitu penentuan tanggal kadaluwarsa dengan jalan menyimpan suatu produk pada kondisi normal sehari-hari dan dilakukan pengamatan terhadap penurunan mutunya hingga mencapai tingkat mutu kadaluwarsanya. Parameter mutu yogurt yang dianalisis selama penyimpanan adalah kadar lemak, kadar protein, pH, total asam tertitrasi, dan keberadaan bakteri koliform. Hasil penelitian untuk karakterisasi awal produk menunjukkan bahwa yogurt kacang hijau memiliki pH sebesar 4.06; total asam tertitrasi (TAT) sebesar 1.90%; kadar lemak sebesar 0.15%; kadar protein sebesar 7.85%; dan bernilai negatif untuk uji keberadaan bakteri koliform…
Keyword: Kacang hijau, Yogurt, Umur simpan, Bogor Agricultural University, Institut Pertanian Bogor, IPB

Judul: Penentuan Umur Simpan Yoghurt Kacang Hijau (Phaeseolus radiatus, Linn).
Abstrak: Mungbean include one of food plant that has been widely recognized by society, even the plants that belonging to the family of pulses has been long cultivated. In Indonesia, mungbean plant is the third-crop beans that are largely grown after soybean and peanuts. Because of its relatively high protein content and the price is relatively cheap, mungbean have a good prospect as a nutritious food that can be consumed by the public, so it is appropriate to be developed in order to increase their economic value. One alternative forms of processing, is to make yogurt from mungbean. However, the short shelf life of yogurt is sometimes become an obstacle, its because the ignoranced consumer about the storage of yogurt. To ensure that the yogurt is still worthy to consumed and not damaged, you need information about shelf life. This study aims to determine shelf life of mungbean yogurt and measuring the decline in the quality of yogurt during storage. This research was conducted with storing mungbean yogurt in the three different temperatures, that is 5 oC, 15 oC and 25 oC. And packaged in three different packaging, that is glass bottles, HDPE and PP. To determine the shelf life of mungbean yogurt, it use Extended Storage Studies (ESS) or the conventional method of determining the expiration date with in the way to save a product at normal conditions of daily and observed for its decrease quality until it reaches the quality level shelf. Quality parameters were analyzed during storage of yogurt that is fat content, protein content, pH, total acid, and the presence of coliform bacteria. The results for the initial characterization showed that the yogurt product having 4.06 in pH; total acid of 1.90%, 0.15% fat content, protein content of 7.85%, and negative values to test the presence of coliform bacteria. During the storage period there was a change of pH, total acid, fat and protein content, and presence of coliform bacteria. Critical parameters of shelf life of mungbean yogurt is the presence of coliform bacteria and total acid. Based on this research, for total acid as a critical parameters during storage, obtained that shelf life of mungbean yogurt is 21 days for yogurts that stored at 5 °C in glass bottle, HDPE and PP. Then, 18 days for yogurt that is stored on temperature of 15 oC in the packaging of HDPE, and 21 days for yogurt that packed with glass and PP packaging materials. Whereas, yogurt that stored at a temperature of 25 oC, has the shortest shelf life, its just six days for the products that are packed with every type of packaging, that are glass, HDPE and PP. For existence of coliform bacteria as a critical parameters, during storage at 5 °C, the yogurt that was not safe again to eat because of the presence of bacterial, is yogurt that packed with HDPE. For the yogurt that stored at a temperature of 15 oC, which already exceeds the safe limit of SNI is yogurt that packed with HDPE and PP. While, yogurt that stored at a temperature
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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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