Judul: Characterization of Fruit Juice Drink Fortified with Yellowfin Tuna Skin Collagen Hydrolysate
Abstrak: Pengolahan limbah kulit dan lambung ikan tuna dapat dimanfaatkan menjadi hidrolisat kolagen yang memiliki antioksidan kuat serta memiliki bobot molekul lebih rendah dari kolagen agar mudah diserap oleh tubuh. Pembuatan hidrolisat kolagen melalui proses hidrolisis secara enzimatis dengan enzim pepsin. Hidrolisat kolagen memiliki potensi dalam pembuatan produk minuman fungsional misalnya sari buah jeruk dan apel yang ditambahkan hidrolisat kolagen dengan konsentrasi 0%; 1,5%; 2%; dan 2,5%. Penambahan hidrolisat kolagen pada minuman sari buah berpengaruh terhadap nilai pH, viskositas, total mikroba, dan aktivitas antioksidan. Penambahan hidrolisat kolagen cenderung menaikan nilai pH dan nilai viskositas. Nilai pH masih dalam rentang pH umum minuman asam, yaitu 3-4. Nilai viskositas cenderung naik pada kedua produk ketika ditambahkan hidrolisat kolagen. Total mikroba pada produk masih dalam rentang SNI 7388:2009 tentang batas maksimum cemaran mikroba dalam pangan sehingga aman dikonsumsi. Aktivitas antioksidan pada produk memiliki nilai yang tinggi dan termasuk ke dalam antioksidan kuat., The treatment of tuna skin and stomach waste can be used as collagen hydrolysate which has strong antioxidants and has a lower molecular weight than collagen to be easily absorbed by the body. The manufacture of collage n hydrolysate through an enzymatic hydrolysis process with the enzyme pepsin. Collagen hydrolyzate has potential in the manufacture of functional beverage products such as cider and apples to which collagen hydrolysate is added with a concentration of 0%; 1,5%; 2%; and 2.5%. The addition of collagen hydrolysate to fruit juice drinks has an influence on pH value, viscosity, total microbes, and antioxidant activity. The addition of collagen hydrolysate tends to increase the pH value and viscosity value. The pH value has 3-4 which is still in the pH range of acidic drinks, and viscosity tends to rise when collagen hydrolysate is added. The total microbes in the product are still within the range of SNI 7388:2009 concerning the maximum limit of microbial contaminants in food for consumption. The antioxidant activity of the product has a high value and is classified as a strong antioxidant.
Keyword: antioxidants, pepsin enzymes, collagen hydrolyzate, tuna fish, cider

Judul: Aplikasi enzim pepsin dari lambung ikan tuna sirip kuning dalam pembuatan hidrolisat kolagen kulit tuna sirip kuning (Thunnus albacares)
Abstrak: Hidrolisat kolagen merupakan produk peptida dengan bobot molekul rendah yang dihasilkan dari proses hidrolisis dengan penambahan enzim pada suhu spesifik. Penelitian ini memiliki tujuan untuk menentukan konsentrasi enzim pepsin dalam proses hidrolisis kolagen dari kulit ikan tuna, serta menentukan karakteristik produk hidrolisat. Penelitian ini dilakukan dengan tiga tahapan yaitu produksi pepsin, ekstraksi kolagen dan hidrolisis kolagen. Ekstraksi kolagen dilakukan menggunakan asam, sedangkan hidrolisis kolagen dilakukan menggunakan enzim pepsin dengan aktivitas 7.000, 14.000 dan 21.000 U. Ekstrak pepsin yang diperoleh memiliki aktivitas sebesar 27.438,50 U/mg. Kolagen yang dihasilkan memiliki bobot molekul 260-150 kDa. Hidrolisat kolagen dengan perlakuan aktivitas pepsin 14.000 dan 21.000 U menghasilkan potongan pita protein dengan bobot molekul 41-3 kDa. Uji aktivitas antioksidan menghasilkan nilai IC50 hidrolisat kolagen dengan perlakuan 7.000 U sebesar 485,9±27,08 ppm, perlakuan 14.000 U sebesar 233,42±2,39 ppm yang paling baik diperoleh hidrolisat kolagen dengan perlakuan 21.000 U sebesar 167,7±0,47 ppm. Hidrolisat kolagen memiliki aktivitas inhibitor ACE pada konsentrasi 0,5 mg/ml protein memperoleh nilai inhibisi paling tinggi pada perlakuan 21.000 U yaitu sebesar 68,63%., Hydrolyzed collagen is a group of peptides with low molecular weight that can be obtained by enzymatic action at a specific incubation temperature. This study aimed to determine the concentration of the pepsin enzyme in the hydrolysis process of collagen from tuna skin and to determine the characteristics of the hydrolyze product. This research was conducted in three stages namely pepsin production, collagen extraction, and collagen hydrolysis. Collagen extraction was carried out using acid, while collagen hydrolysis was carried out using the enzyme pepsin with an activity of 7.000, 14.000 and 21.000 U. Pepsin extract obtained had an activity of 27.438,50 U/mg. The resulting collagen had a molecular weight of 260-150 kDa. Collagen hydrolyze with pepsin activity 14.000 and 21.000 U resulted band in low molecular weight sections in the range of 41-3 kDa. The test of antioxidant activity resulting IC50 value of collagen hydrolyze with 7.000 U treatment was 485,9 ± 27,08 ppm, the 14.000 U treatment was 233,42 ± 2,39 ppm, the best obtained was collagen hydrolyze with 21.000 U treatment of 167,7 ± 0,47 ppm. Collagen hydrolyze has an ACE inhibitory activity at a concentration of 0,5 mg/ml protein, obtaining the highest inhibition value at 21.000 U, which is 68,63%.
Keyword: Antioxidant, Extraction, Hydrolysis, Peptide

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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