Judul: Kajian Proses Pasteurisasi Jelly Drink Cincau Hijau-Rosela Dalam Kaleng untuk Menghasilkan Daya Antioksidan Optimum.
Abstrak: Green grass jelly (Premna oblongifolia Merr.) and roselle (Hibiscus sabdariffa L. Merr.) are local food commodities that can be used to alleviate increased prevalence of metabolic syndrome. The purpose of this research is to study thermal process of green grass jelly-roselle jelly drink product with minimum antioxidant capacity decrease. This research was done in two stages; (1) thermal process treatment and (2) product’s antioxidant capacity characterization. Thermal process treatment is carried out by treating the samples at different combination of time and temperature to achieve pasteurization value equal to 6D85 (at 65 °C pasteurization requires 7.2 minutes, at 75 °C req. 5.25 minutes, and 85 °C req. 4 minutes). Antioxidant characterization of the product are used to determine the effect of thermal processes on the functional character of the product. Pasteurized product at 65 °C has the highest total phenolic content (58.19 mg GAE/ g sample) and antioxidant activity (IC50 0.38 g/mL). The highest total chlorophyll content is pasteurized product at 85 °C (17.21 mg/ 100 g sample). Each product doesn’t show any significant difference in crude fiber content. Based on it functional characteristic, pasteurized product at 65 °C is product that undergo optimal pasteurization process.
Keyword: antioxidant capacity, green grass jelly, pasteurization, roselle

Judul: Evaluasi Mutu Fisik, Mikrobiologi, dan Sifat Fungsional Gel Cincau Hijau (Premna Oblongifolia Merr.) dalam Kemasan dengan Perlakuan Pasteurisasi
Abstrak: Green grass (Premna oblongifolia Merr.) jelly is one of functional food, that has been widely studied for it’s beneficial effect. The purposes of this study are to design pasteurization condition of green grass jelly and to study the effect of pasteurization on the jelly properties. Thermal schedule based on 6D concept targetting S. aureus were applied on the product in three combinations of time and temperature. The combinations were 36 minutes in 75°C, 25 minutes in 85°C, and 22 minutes in 95°C. Pasteurization reduced pH value, L value, a value, b value, rate of syneresis, gel strenght, rupture point, and rigidity. Pasteurization also decreased the total of chloropyll, a chlorophyll, b chlorophyll, phenol, and capacity of antioxidant. But, pasteurization increased the total dietary fiber (TDF, SDF, dan IDF). The results showed that the best pasteurization condition was 22 minutes in 95°C based on the physical and functional properties. Physical characteristics of the selected product were 8.24 of pH value, 22.64 of L value, -0.60 of a value, 4.20 of b value, 2.84% of syneresis rate, 493.7105 g/cm2 of gel strength, 3.13 cm of rupture point, and 1.9955 g/cm of rigidity. Moreover, the functional characteristics were 1.2220 mg/L of total chloropyhll , 1.0385 mg/L of a chlorophyll, 0.1838 mg/L of b chlorophyll, 36.1220 mg GAE/L of total phenol, 19.1591 mg AEAC/L of antioxidant capacity, 3.0275% of TDF, 2.1743% of SDF, and 0.8532% of IDF. The product was organoleptically acceptable and microbiologically safe.
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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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