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 Effect of Papain Enzyme Levels on the Byproducts of the Eel Industry (Anguilla bicolor bicolor)
Abstrak: Hasil samping ikan sidat dapat dikembangkan menjadi produk bernilai ekonomi tinggi yaitu dengan pembuatan hidrolisat protein. Hidrolisat protein merupakan hasil penguraian protein menjadi peptida sederhana melalui proses hidrolisis oleh enzim, asam, atau basa. Tujuan penelitian ini adalah menentukan pengaruh penambahan enzim papain (1, 2, 3%) terhadap derajat hidrolisis, bobot molekul dan aktivitas antioksidan serta struktur mikroskopis hidrolisat protein hasil samping ikan sidat segar dan rebus. Hidrolisat protein dengan perlakuan segar dan rebus menggunakan enzim papain 1, 2, dan 3% tidak berpengaruh nyata terhadap derajat hidrolisis. Hidrolisis dilakukan pada suhu 55℃ selama 3 jam dengan waterbath shaker. Derajat hidrolisis tertinggi yaitu pada hidrolisat segar 3% dan rebus 1%. Bobot molekul hidrolisat protein hasil samping ikan sidat yang diperoleh berkisar 7-11 kDa. Aktivitas dan kapasitas antioksidan tertinggi terdapat pada sampel yang telah diberi perlakuan penambahan enzim yakni hidrolisat segar dan hidrolisat rebus., The by-product of eel can be developed into a product with high economic value by making protein hydrolysate. Protein hydrolysate is the result of the breakdown of proteins into simple peptides through the hydrolysis process by enzymes, acids, or bases. This study aimed to determine the effect of the addition of papain enzymes (1, 2, 3%) on the degree of hydrolysis, molecular weight, and antioxidant activity as well as the microscopic structure of protein hydrolysate byproducts of fresh and boiled eel. Protein hydrolyzate with fresh and boiled treatment using papain 1, 2, and 3% enzymes did not significantly affect the degree of hydrolysis. Hydrolysis was carried out at 55℃ for 3 hours with a water bath shaker. The highest degree of hydrolysis was at 3% fresh hydrolyzate and 1% boiled. The molecular weight of the protein hydrolyzate by-product of eel obtained ranged from 7-11 kDa. The highest antioxidant activity and capacity were found in samples that had been treated with the addition of enzymes, namely fresh hydrolyzate, and boiled hydrolyzate.
Keyword: antioxidant, by-product, hydrolysis, papain, ntioxidant, by-product, hydrolysis, papain

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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