Judul: Quality changes of freeze dried catfish surimi and predicting of shelf life
Abstrak: Indonesian fish consumption rate in 2012 reached 30.17 kg/capita/year, but still lower than Singapore fish consumption levels of 48.1 kg/capita/year, even Malaysia reached the high level of fish consumption up to 56.61 kg/capita/year. Catfish as surimi raw material has a tremendous opportunity to be developed in order to utilize oversized catfish as an alternative efficiency in trade. Catfish easily cultivated and affordable for the grassroots level. Selling price of catfish is determined by its size, because it was adapted to the target market. Catfish with the normal size (7-10 fishes/kg) did not encounter sales problems due to high market demand. The problem faced is marketing catfish that weighs more than the consumption size (oversize) that accounted for 10% in each production cycle. The aforemention problems can occur lossing for farmers due to the many oversized catfish that will not sold. Therefore one of the proposed solutions is utilization of catfish in the manufacture of surimi as intermediate raw materials. Research and study of surimi has evolved, but the major problems are the sustainability and continuity of raw materials. Catfish as a aquaculture commodity is expected to be the solution. Surimi products have increased demand in several countries, including in Asia and Europe region. Further processing of surimi into powder form to be one of the important studies in recent years, surimi drying installations are considered to reduce the cost of freezing during storing and transporting. This study aims to determine the best concentration of NaHCO3 duration of soaking, surimi washing frequency and the best dryoprotectant, to evaluate quality changes of dried surimi and to estimate its shelf life. This research is expected to be useful as an initial step oversized catfish used as raw material for surimi products (intermediate product). This study provides an alternative technology in the manufacture of surimi and surimi industry to increase the potential raw material through using inexpensive types of fish that have not been used optimally. This study is conducted into two step mainly the process on making dried catfish surimi and surimi shelf life estimation. The first step research consisted of defatting process, selecting of surimi washing frequency, determination of dryoprotectant, as well as the comparison of the physicochemical properties of wet surimi and dried surimi. Lipid concentration is a key in the process of deffating, the best determination washing frequency is measured through whiteness value, WHC, gel strength, salt soluble protein content, pH value and sensory parameters (folding test and teeth cutting test) analysis. The second step is determination of the best dryoprotectant, the treatments given are trehalose 6%, carrageenan 2%, and mixture dryoprotectant (4% sorbitol, 4% sucrose and 0.5% phosphate). Some test were performed in order to measure and to find out the best dryoprotectant such as yield, water holding capacity, gel strength, salt soluble proteins, density, rehydration ratio, emulsion and foaming properties and the microstructure. The final step were comparison of fish meat, 8 wet surimi, dried surimi and kamaboko through measuring of SEM (microstruture) testing, yield, proximate, water holding capacity, gel strength, measurement of pH, gel strength and sensory testing (folding
Keyword: catfish, freeze dried surimi, microstructure, shelf life, trehalose

Judul: Karakterisasi Mutu Surimi Segar Ikan Lele Dumbo ( Clarias gariepinus) dan Aplikasinya Untuk Pembuatan Kamaboko
Abstrak: Catfish is one of the flagship products of aquaculture. It is estimated that the production of catfish will continue to increase along with the increase in commodity production of freshwater seed. The increasment of catfish production needs to be balanced with the diversification of the use of catfish products, especially for oversized catfish (10% for every production cycle) which are normally less marketable. One of the alternatives that can be applied is by manufacturing surimi catfish. This study aimed to characterize the quality of catfish based surimi and determine its class in quality standards of surimi-based testing kamaboko with or without the addition of starch. This experiment used four types of washing treatment, which were: Treatment A (without the addition of NaCl and NaHCO3), Treatment B (addition of NaHCO3 0.5%), Treatment C (addition of NaCl 0.3%) and Treatment D (combination NaHCO3 0.5 % and 0.3% NaCl) to obtain the best washing treatment. The results of the experiment showed that treatment D (a combination of 0.5% NaHCO3 and NaCl 0.3%) possessed the best results with a yield of 34.92% (p>0.05), the pH of 6.86 (p>0.05), whiteness 78.97% (p<0.05), gel strength of 505.43 g.cm (p<0.05), and salt-soluble proteins 5.41% (p<0.05). Application of catfish based surimi in kamaboko showed that the score for folding test was 4.67 that was interpreted as "not crack when folded quarter circle", bite test was 7.03 that was considered as "strong enough" and rating hedonic test showed of 5.9 value that was categorized as "somewhat like". Pursuant to the data obtained in this study, surimi catfish was categorized in the fifth grade "5" on the quality standards of surimi-based testing kamaboko with or without the addition of starch.
Keyword: Bogor Agricultural University (IPB), catfish surimi, washing treatments, catfish, kamaboko

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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