Judul: The Effect of Drying Methods on  Pepsin Activity from Yellowfin Tuna Gastric (Thunnus albacares)
Abstrak: Pepsin merupakan enzim proteolitik yang aktif dalam kondisi asam. Bahan baku alternatif penghasil pepsin adalah lambung ikan tuna sirip kuning. Tujuan penelitian ini mengkarakterisasi enzim pepsin dari lambung tuna sirip kuning dan menentukan pengaruh pengeringan terhadap aktivitas enzim. Metode pengeringan yang digunakan, yaitu spray drying dan freeze drying. Aktivitas spesifik ekstrak kasar pepsin 19.982,52 U/mg, dengan Vmaks 50.000 mmol/s dan Km 0,5 mM. Pepsin optimum pada suhu 50°C dan pH 2, serta memiliki bobot molekul 32,837 kDa. Pepsin hasil spray dryer memiliki aktivitas spesifik 7693,5 U/mg, serta nilai Vmaks 833,33 mmol/s dan Km 0,5 mM, sedangkan hasil freeze dryer memiliki aktivitas spesifik 8606,75 U/mg, serta nilai Vmaks dan Km berturut-turut 1666,67 mmol/s dan 0,833 mM. Bobot molekul pepsin hasil pengeringan spray dryer 33,764 kDa dan freeze dryer 33,64 kDa. Hasil penelitian menunjukkan aktivitas spesifik pepsin menurun setelah proses pengeringan., Pepsin is a proteolytic enzyme that has the ability active in acidic conditions. The alternative raw material for pepsin is the stomach of yellowfin tuna. The purpose of this study was to characterize the pepsin enzyme from the stomach of yellowfin tuna and to analyze the enzyme activity after drying process. The drying method was used spray drying and freeze drying. The specific activity of pepsin crude extract was 19.982,52 U/mg, with Vmax 50.000 mmol/s and Km 0,5 mM. The optimum pepsin at 50oC temperature and pH 2, and has a molecular weight 31,837 kDa. The dried pepsin with spray drying has a specific activity 7693,5 U/mg, with Vmax 833,33 mmol/s and Km 0,5 mM, whereas with freeze drying has a specific activity 8606,75 U/mg, Vmax and Km values respectively 1666,67 mmol/s and 0,833 mM. The molecular weight of pepsin enzyme with spray drying 33,764 kDa and freeze drying 33,64 kDa. The results showed the specific activity of pepsin decreased after the drying process
Keyword: Aktivitas enzim, Pengeringan beku, Pengeringan semprot, Pepsin

Judul: Optimization of Spray Drying Temperature and Microencapsulation of Maltodextrin to Pepsin Enzyme Acitvity from the Gastric of Yellowfin Tuna (Thunnus albacares)
Abstrak: Enzim pepsin merupakan enzim pada pencernaan utama dalam perut yang berada di epitel dinding lambung. Penelitian terdahulu melakukan pengeringan pepsin tanpa bahan penyalut memperoleh penurunan aktivitas pepsin yang signifikan, yaitu 71% pada spray drying dan 57% pada freeze drying. Oleh karena itu tujuan penelitian ini adalah menentukan pengaruh penggunaan maltodekstrin dengan beberapa konsentrasi terhadap aktivitas enzim pepsin dari lambung tuna. Fungsi mikroenkapsulasi yaitu melindungi bahan inti terhadap degradasi dari pengaruh lingkungan. Proses mikroenkapsulasi yang digunakan pada penelitian ini yaitu melalui penambahan penyalut maltodekstrin dengan beberapa konsentrasi (1%, 2%, 3%) lalu dikeringkan dengan spray dryer. Penambahan bahan penyalut maltodekstrin berpengaruh nyata terhadap nilai aktivitas spesifik enzim pepsin. Perlakuan terbaik berdasarkan aktivitas spesifiknya yaitu penggunaan maltodekstrin 2% dan dikeringkan dengan suhu spray dryer 150℃. Karakteristik enzim pepsin bubuk tersebut memiliki aktivitas spesifik 27.810,33 U/mg, Vmaks 3333 mmol/s, Km 2,3 mM , dan bobot molekul 31,841 kDa., Pepsin enzyme is the main digestive enzyme in the stomach that is in the epithelium of the stomach wall. Previous research on drying pepsin without a padding material gained a significant decrease in pepsin activity, which is 71% in spray drying and 57% in freeze drying. Therefore, the purpose of this study is to determine the effect of maltodextrin with some concentration on the activity of the pepsin from gastric of tuna. The function of microencapsulation is to protect core materials against degradation. The microencapsulation method used in this study is the addition of maltodextrin pads with some concentration (1%, 2%, 3%) after which it is dried with a spray dryer. The addition of maltodextrin method has a real effect on specific activity of pepsin enzymes. The best treatment based on its specific activity is a 2% maltodextrin that is dried with a spray dryer temperature of 150 ° C. The enzyme pepsin powder with 2% maltodextrin obtained a specific activity value of 27,810.33 U/mg, Vmaks 3333 mmol/s, Km 2.3 mM, and a molecular weight of 31,841 kDa.
Keyword: enzyme activity, maltodextrin, microencapsulation, pepsin enzyme

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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