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 (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: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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