Judul: Recovery Enzim Katepsin dari Air Cucian Surimi dengan Pra- perlakuan pH dan Suhu
Abstrak: Surimi, which is used for food industry such as kamaboko, is an itermediate fish product. The arising problem with surimi production is liquid waste disposal. Surimi wash water has poluted the environment because of the high Biological Oxygen Demand (BOD). Liquid waste from surimi production is contained with rich organic matter such as enzyme chatepsin. The purpose of this research is determine pH and temperature for enzyme cathepsin recovery from surimi wash water. Temperature and pH which used for recovery are 30°C, 40°C, 50°C, 60°C, 70°C and 3, 4, 5, 6, 7. Sample from every treatment tested with enzyme cathepsin activity assay and total protein. The result from both assay is used to determine spesific enzyme chatepsin activity and purification fold. Recovery enzyme cathepsin was maximised when surimi wash water was treated with acid (pH 5) and heat (60°C) based on spesific enzyme cathepsin activity. Optimized purifification fold was achieved (117) when surimi wash water was treated with acid (pH 5) and heat (60°C).
Keyword: temperature, surimi wash water, pH, enzyme recovery, cathepsin

Judul: The Role of The Tripsin Enzyme of Big Eye Tuna Improving The Quality of Red Tilapia Surimi
Abstrak: Pemanfaatan limbah jeroan ikan dapat didgunakan sebagai sumber potensial enzim pencernaan, salah satunya enzim tripsin yang diekstrak dari usus ikan tuna mata besar. Pemanfaatan enzim protease pada produk perikanan sudah banyak, contohnya pada surimi. Surimi merupakan produk perikanan yang memiliki tekstur unik dan gizi yang tinggi. Bahan baku surimi lebih sering menggunakan ikan berdaging putih banyak terdapat di spesies ikan air tawar, salah satunya ikan nila. Ikan nila sangat cocok untuk pembuatan surimi karena dagingnya yang tebal dan berwarna putih. Tujuan penelitian ini adalah ekstraksi dan karakterisasi tripsin dari usus ikan tuna mata besar serta menentukan kosentrasi tripsin terbaik dalam meningkatan mutu surimi ikan nila merah. Penelitian terbagi menjadi dua tahap, yang pertama yaitu ekstaksi dan karakterisasi enzim tripsin. Tahap kedua yaitu aplikasi enzim tripsin pada pembuatan surimi. Analisis yang digunakan pada penelitian meliputi penentuan aktivitas, konsentrasi protein, suhu dan pH optimum enzim. Konsentrasi tripsin 0%, 1%, 2%, 3%, 4% (v/b) ditambahkan dalam pembuatan surimi dan kemudian dilihat pengaruhnya terhadap kualitas surimi yang dihasilkan. Analisis data dilakukan menggunakan metode Rancangan Acak Lengkap (RAL) dengan tiga ulangan. Ekstrak kasar tripsin memiliki aktivitas 0,121 U/mL. sedangkan untuk konsentrasi protein yang didapatkan yaitu 0,158 mg/mL dengan suhu optimum 50 ºC dan pH 7. Surimi dengan penambahan tripsin 2% menunjukkan hasil terbaik yaitu kadar air 81,54%, kadar protein 13,99%, kadar abu 0,23%, kadar lemak 0,48%, pH 7, protein larut garam (PLG) 0,9 mg/mL, WHC 18%, derajat putih 62%, ukuran partikel 1054 μm, kenampakan 8, uji lipat 2,7 dan uji gigit 6,5., Utilization of fish offal waste can be used as a potential source of digestive enzymes, one of which is the trypsin enzyme extracted from the intestines of bigeye tuna. There are many uses of protease enzymes in fisheries product, for example in surimi. Surimi is a fishery product that has a unique texture and high nutrition. The raw material for surimi more often uses white-fleshed fish, which is found in many freshwater fish species, one of which is tilapia. Tilapia is very suitable for making surimi because of its thick and white flesh. The purpose of this study was to extract and characterize trypsin from the intestines of bigeye tuna and to determine the best trypsin concentration in improving the quality of red tilapia surimi. The research was divided into two stages, the first was extraction and characterization of the trypsin enzyme. The second stage is the application of the trypsin enzyme in the manufacture of surimi. The analysis used in this study included determining the activity, protein concentration, temperature and optimum pH of the enzyme. Trypsin concentrations of 0%, 1%, 2%, 3%, 4% (v/w) were added in the manufacture of surimi and then seen their effect on the quality of the surimi produced. Data analysis was performed using a completely randomized design (CRD) method with three replications. The crude trypsin extract has an activity of 0.121 U/mL. while the protein concentration obtained was 0.158 mg/mL with an optimum temperature of 50 C and pH 7. Surimi with the addition of 2% trypsin showed the best results, namely 81.54% water content, 13.99% protein content, 0.23%
Keyword: pH, proximate, protease

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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