Judul: Study Inhibitor Protease from Swamp Eel (Monopterus albus) and Its Role in Improving The Quality of Surimi
Abstrak: Abstrak Inhibitor protease adalah senyawa yang berpotensi menghambat aktivitas suatu protease atau beberapa enzim protease. Ini memiliki peran penting dalam pengolahan ikan untuk mencegah penurunan kualitas. Penelitian ini bertujuan untuk mengetahui aktivitas penghambatan plasma (crude dan fraksi) belut sawah (Monopterus albus) terhadap enzim papain dan pengaruh crude plasma dan fraksi etanol plasma belut sawah pada konsentrasi yang berbeda (0, 0,25, 0,5, 0,75, 1, 1,5, 2 mg/g) terhadap kualitas surimi ikan mujair (Oreochromis mossambicus). Parameter yang dianalisis adalah kadar protein, aktivitas penghambatan enzim papain, SDS-PAGE, kekuatan gel, expressible moisture, derajad putih, struktur mikro (SEM), kadar asam amino, zimogram, kelarutan protein, pola autolisis surimi, persen inhibisi. Hasil penelitian menunjukkan bahwa jumlah protein dalam plasma yang difraksinasi dengan etanol mengalami penurunan. Efektivitas dalam menghambat enzim papain meningkat dibandingkan dengan plasma kasar, dari 65 menjadi 128,56% per mg protein. Analisis dengan elektroforesis gel natrium dodesil sulfat-poliakrilamida menunjukkan bahwa kompleks protein alfa-2-makroglobulin dalam plasma sidat rawa terdiri dari dua subunit yang berbeda yaitu 120 kDa dan 110 kDa. Fraksi etanol plasma dapat mempertahankan kekuatan gel, ekspresi kelembaban, struktur mikro, kelarutan protein, dan persen penghambatan dalam autolisis ikan nila surimi dari aktivitas protease yang menyebabkan fenomena modori lebih baik daripada plasma mentah. Keputihan menurun dengan meningkatnya konsentrasi plasma yang digunakan. SDS-PAGE untuk analisis pola autolisis menunjukkan bahwa efektivitas plasma kasar sebagai inhibitor protease menurun seiring dengan peningkatan konsentrasi. Terjadi peningkatan penghambatan autolisis pada fraksi etanol plasma pada konsentrasi 1,5 mg/g. Proses pemurnain lebih lanjut mungkin diperlukan untuk memastikan hasil yang lebih baik dalam penerapan plasma untuk menghasilkan surimi yang berkualitas baik., Abstract A protease inhibitor is a compound that potentially could inhibit the activity of a protease or some protease enzymes. It has a significant role in fish processing to prevent quality deterioration. The study aimed to investigate the inhibitory activity of wild swamp eel (Monopterus albus) crude plasma and plasma fractionated with ethanol to papain enzyme and their effect on the quality of tilapia (Oreochromis mossambicus) surimi at different concentrations (0, 0.25, 0.5, 0.75, 1, 1.5, 2 mg/g). The parameters analyzed were protein content, inhibitory activity to papain enzyme, sodium dodecyl sulfate-polyacrylamide gel electrophoresis to demonstrate protein profile, gel strength, expressible moisture, whiteness, scanning electron microscopy, amino acid content, zymogram, protein solubility, autolysi pattern, and percent of inhibition. The result showed that the amount of protein in the plasma fractionated with ethanol was decreased. The effectiveness in inhibiting papain enzyme was increased compared to that of the crude plasma, from 65 to 128.56% per mg protein. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the protein complex alpha-2-macroglobulin in wild swamp eel plasma consists of two different subunits of 120 kDa and 110 kDa. Plasma ethanol fraction could maintain gel strength, expressible moisture, microstructure, protein solubility, and percent inhibition in autolysis of tilapia surimi from protease activity that caused modori phenomenon better than crude plasma. The whiteness decreased as the concentration of plasma used increased. SDS-PAGE for autolysis pattern analysis showed that the effectiveness of crude plasma as a protease inhibitor decreased as the concentration was increased. There was an increase in the inhibition of autolysis
Keyword: Autolysis, crude plasma, modori, plasma ethanol fraction, surimi, swamp eel

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: 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.
Keyword: