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: Adding effect of phenolic compound on the gel properties of catfish (Clarias gariepinus) surimi
Abstrak: Catfish (Clarias gariepinus) has potential as raw material of surimi because the production is abundant. However, research is needed to enhance the gel strength of catfish surimi. The effect of leaching times on the proximate composition and gel properties of catfish surimi were studied. Three times of leaching produced better characteristics of the gel rather than leaching 1 and 2 times. Commercial tannic acid and tea leaf extract were added in producing surimi gel. Ethanol extracts from tea leaves powder 100 mesh size used in surimi since had higher total phenol content (47.34 mg/g) than 60 mesh. The effects of different oxidised phenolic compounds (tannic acid (K) and tea leaf extract (T) at different levels (0–0.50%) of protein content) on the properties of gels from catfish (Clarias gariepinus) surimi were investigated. Gels with addition of 0.50% tannic acid and 0.4% tea extract increased in WHC by 27.27 % and 20.5% and decreased in EMC by 34.55% and 44.85% respectively. The highests deformation, gel strength and breaking force had been reached by 0.5% tannic acid and 0.4% tea leaf extract. Whiteness decreased slightly with the increasing of phenolic concentration. Tannic acid 0.5% and tea leaf extract 0.4% gave the best textural properties on gel surimi. Result of sensory evaluation indicated that addition of oxidised phenolic compounds had positive impact in folding test and teeth cutting test however there were no effect in taste of surimi gels. Gels with addition of all oxidised phenolics exhibited fibrillar structures which were more compact in compared to control. Optimum concentration of phenolic compound to enhance catfish surimi gel are 0.5 % for tannic acid and 0.4% for tea leaf extract.
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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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