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: Enzyme Trypsin Activity from Yellowfin Tuna (Thunnus albacares) with Different Drying Methods
Abstrak: Enzim telah banyak digunakan dalam berbagai proses kimiawi, baik dalam bidang industri maupun dalam bidang bioteknologi salah satunya yaitu enzim tripsin. Enzim tripsin dari jeroan ikan bisa menjadi alternatif dari enzim tripsin komersil yang berasal dari babi dan sapi. Tujuan penelitian ini adalah mengkarakterisasi enzim tripsin dan menganalisis pengaruh pengeringan terhadap karakteristik enzim tripsin yang dihasilkan. Metode pengeringan yang digunakan, yaitu spray drying dan freeze drying. Nilai aktivitas spesifik dari ekstrak kasar tripsin 0,053 U/mg, dengan nilai Vmaks 0,0050 mmol/s dan Km 0,405 mM. Enzim tripsin didapatkan optimum pada suhu 60°C dan pH 8, dan memiliki bobot molekul sebesar 29,346 kDa. Tripsin hasil pengeringan menggunakan spray dryer memiliki aktivitas spesifik 0,068 U/mg, serta nilai Vmaks 0,0018 mmol/s dan Km 0,808 mM, sedangkan dengan freeze dryer memiliki aktivitas spesifik 0,069 U/mg, serta nilai Vmaks 0,0041mmol/s dan Km 0,317 mM. Bobot molekul tripsin dengan pengeringan spray dryer sebesar 28,119 kDa dan freeze dryer 28,665 kDa. Hasil penelitian menunjukan bahwa aktivitas spesifik tripsin tidak berpengaruh nyata setelah proses pengeringan., Enzymes have been used in various chemical process, either in industry or biotechnology and one of them is trypsin enzyme. Enzyme from fish viscera could be used as an alternative of commercial trypsin from pig or cow. The purpose of this study was to characterize the trypsin enzyme and and to analyze the enzyme activity after drying process. The specific activity of trypsin crude extract was 0,053 U/mg, with Vmax value 0,0050 mmol/s and Km 0,405 mM. The optimum trypsin enzyme at 60oC and pH 8, and has a molecular weight 29,346 kDa. The dried trypsin with spray drying has a specific activity value 0,068 U/mg, with Vmax value 0,0018 mmol/s and Km 0,808 mM, whereas with freeze drying has a specific activity value 0,069 U/mg, Vmax value 0,0041 mmol/s and Km 0,317 mM. The molecular weight of trypsin enzyme with spray drying was 28,119 kDa and freeze drying was 28,665 kDa. The results showed the specific activity of trypsin had no significant effect after the drying process.
Keyword: Enzim tripsin, Aktivitas enzim, Ikan tuna sirip kuning, Spray dryer, freeze dryer

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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