Judul: Pembuatan starter kering bakteri asam laktat dan pengaruhnya terhadap karakteristik dadih yang dihasilkan
Abstrak: Dadih merupakan bahan pangan tradisional dari Sumatera Barat hasil fermentasi alami susu kerbau. Proses fermentasi alami ini melibatkan sejumlah mikroorganisme yang meliputi bakteri gram positif (Lactobacillus plantarum, L. brevis, Streptococcus agalactiae, S. uberis dan Bacillus cereus) dan bakteri gram negatif (Escherichia coli dan Klebsiella sp) (Sirait et al.,1995). Kehadiran bakteri gram negatif yang bersifat patogen dapat menjadi kendala untuk mendapatkan produk pangan yang aman dan sehat untuk dikonsumsi serta mudah dalam pemasaran produk, disebabkan oleh aspek keamanan yang kurang terjamin. Pengolahan melalui proses fermentasi yang lebih terkendali dengan menggunakan starter bakteri asam laktat (BAL) tanpa melibatkan bakteri patogen diharapkan akan meningkatkan kualitas dadih yang dihasilkan. Penyediaan kultur dengan pengawetan dalam bentuk kering akan memudahkan cara penanganan kultur starter, sehingga fermentasi lebih terkontrol dan kualitas produk lebih terjamin. Disamping itu, ketersediaan kultur starter kering akan mempermudah distribusi dan transportasi kultur starter karena kultur starter kering dapat dikirim untuk jarak jauh tanpa kehilangan aktivitas dari BAL serta mempunyai daya simpan yang lama. Bahan baku yang digunakan dalam pembuatan dadih di Sumatra Barat berasal dari susu kerbau. Ketesediaan susu kerbau sangat terbatas sehingga alternatif yang digunakan yaitu susu sapi yang dimodifikasi dengan susu skim dan bahan pengisi agar-agar sehingga diharapkan menghasilkan dadih yang mempunyai karakteristik mirip dengan dadih susu kerbau. Penelitian ini bertujuan mengetahui pembuatan starter kering bakteri asam laktat (kombinasi Streptococcus thermophilus dan Lactobacillus casei serta Lactobacillus bulgaricus dan Lactobacillus casei) dan pengaruhnya terhadap karakteristik dadih susu sapi yang dihasilkan…
Keyword: Dadih, Starter kering bakteri asam laktat, Bogor Agricultural University, Institut Pertanian Bogor, IPB

Judul: Pembuatan Starter Kering Bakteri Asam Laktat dan Pengaruhnya terhadap Karakteristik Dadih Susu Sapi yang Dihasilkan.
Abstrak: Dadih is a traditional food from West Sumatera resulted from natural fermentation of buffalo milk. This natural fermentation process involves a number of microorganisms, including gram-positive and gram-negative bacteria. The presence of gram negative bacteria that are pathogenic can become an obstacle to get safe and healthy food product to consume and easy in the marketing of products, due to the security aspect is less reliable. The processing through a more controlled fermentation process using lactic acid bacteria starter without involving the bacterial pathogens are expected to improve the quality of the resulting dadih. The provision of culture with the preservation in the dry form will facilitate the handling of starter cultures, so that the fermentation is more controlled and the product quality is more assured. Besides that, the availability of dry starter cultures will facilitate the distribution and transportation of starter cultures because dry starter cultures can be sent for long distances without losing the activity of Lactic acid bacteria and have a long storage. Raw materials used in the manufacture of dadih in West Sumatera derived from buffalo milk. The availability of buffalo milk is very limited, that, the alternative used is cow modified with skim milk and jelly therefore it is expected produce Dadih which has the characteristic similar with dadih from buffalo’s milk. This study aimed to verify the making of dry starter of lactic acid bacteria (the combination Streptococcus thermophilus and Lactobacillus casei also Lactobacillus bulgaricus and Lactobacillus casei) and its effect towards the characteristic of resulting cow’s milk dadih. Various analytical results indicate that the interaction of combinations of lactic acid bacteria starter and concentration of dried starter powder of lactic acid bacteria significantly affect to the pH value and moisture content of dadih. interaction of a combination of lactic acid bacteria starter and dried starter powder concentration of lactic acid bacteria did not influence significantly to the value of titrable acid total, viscosity, ash content, and the total amount of lactic acid bacteria in dadih. Friedman test results showed that the assessment of panelists for color, aroma, taste, texture, and general acceptance of dadih was not significantly different. Based on weighting method for the determination of the best dadih products, showed that dadih fermented by a combination of starter S. thermophilus: L. casei (1 : 2) as much as three grams of powder has the highest weight value. Thus, the recommendation of the best dadih product is dadih product fermented by a combination of starter S. thermophilus : L. casei (1: 2) as much as three grams of dried starter powder. Microbiological test results showed that the lowest total lactic acid bacteria contained in dadih products, that is 8.4 x 109 CFU/ml. Thus, the dadih is eligible as fermented milk for the minimum amount of total lactic acid bacteria ranged 106-109 CFU/ml (Sari, 2007).
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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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