Judul: Extraction optimization and characterization of fish oil from catfish (Clarias sp.) By-product
Abstrak: Catfish is a freshwater aquaculture fish production ranks first in Indonesia, with an increased production of 60% between 2009 and 2011. This high production resulted in an also high by-product. In this research, the aim was to characterize the raw material catfish by-product by looking at the raw material yield, proximatecontent, heavy metal residues, oil yield and fatty acid profiles of catfish by-product, to provide preliminary informationon the raw materials used and see the prospective by-product to be used in the production of fish oil. In this study was also conducted the optimization of production of fish oil extracted from the by-product selected using the low and high temperature treatment, heating time, and the ratio of solvents and materials. Yield of raw material catfish on each section by-product from the largest to the smallest are head 15,77%, gonad 8,17%, skin 4,55%, liver 1,14%, and intestine 0,81% repectively. Proximate content showed the highest fat content obtained from the intestine was 7%, while the fat content of the skin were 6%. Residues of heavy metals As, Hg, Cd, and Ni, obtained results are still below the threshold, but higher Pb found in the gut that is 1,82 ppm. The yield of oil producted by each by-product are intestine 8,15%; gonad 5,6%; head 4,39%, skin 4,26% and liver 3,63%. Fatty acid profile of catfish by-product of total saturated fatty acids (SFA) are gonad 20,48%; head 32,4%; intestine 29,63%; skin 33,17%; heart 25,16%. Total monounsaturated fatty acids (MUFA) are gonad 14,8%; head 27,14% intestine 24,78%; skin 24,96%; heart 16,22%. Total polyunsaturated fatty acids (PUFA) are gonad 26,65%; head 13,64% intestine 21,38%; skin 18,95%; heart 22,25%. Of the overall characterization of the raw materials, skin is a by-product that are productive to be produced as fish oil. Best extraction method as found in the treatment with a low temperature of 50 ºC with a 30 minute extraction time, treatment comparison does not give effect to the oxidation parameter values. Optimization using response surface method with the treatment of temperature and longer extraction time against oxidation and oil yield parameters, yield best oil production range with temperature (45-50) ºC with heating time (30-40) minutes. The optimum point is a located at 49,76 ºC with extraction time of 38,2 minutes heating time with the oidation parameter anisidine values 235,49 meq/kg; peroxide values 38,17 meq/kg; TOTOX 301,15, free fatty acids 0,50%; acid values 0,99 mgKOH/g; and the highest yield of 8%. Fatty acids that are found in most catfish skin oil is monounsaturated fatty acids 29,38% then followed 28% saturated fatty acids, and polyunsaturated fatty acids 14, 8%.
Keyword: by-product, catfish, extraction, fish oil, optimization

Judul: Extraction Optimization and Characterization of Fish Oil from Catfish (Pangasius hypophthalmus) By-product
Abstrak: Cultivation of catfish (Pangasius hypophthalmus) increased rapidly in 2008, as many as 102,010 tonnes, Increasing almost three times compared to the previous year production 36,780 tons. In 2010 the volume of catfish aquaculture production reached 147,890 tonnes, and is expected to reach 400,000 tons in 2011 (increased 70%). Catfish plays an important role in aquaculture production, and by 2013 the Indonesian government put catfish as one of the four commodities that enter the flagship program of fisheries industrialization. Unfortunately increasing production of catfish also resulted in increasing its by-product. The yield of catfish by-product is very high (50%). Therefore catfish by-product are potential to be a source of rich omega-3 oils. The purpose of this study was to characterize by-products and to determine the type of catfish by-product that are potential on producing fish oil, to determine the fatty acid profile of catfish by-product, selecting the best extraction and determination of the quality of fish oil of selected catfish by-product, and the optimization of production of fish oil by the response surface method. Based on the data obtained, the by-product selected for further extraction method were the catfish skin. The selected extraction was temperature and time of 60°C and 30 minutes, respectively. The optimum extraction process was obtained at 62.99°C for 32.68 minutes, with oxidation characteristic are yield, peroxide value, free fatty acid, p-anisidine value, acid value and total oxidation of 14.73%. , 73.15 meq/kg, 1.01%, 316.934 meq/kg, 1.06 mg KOH/kg and 512.508 respectively.
Keyword: by-product, catfish, extraction, fatty acids, optimization

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf