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: Gel Cincau Hijau (Premna oblongifolia Merr.) Manis yang Diperkaya dengan Antioksidan dan Flavor Ekstrak Pandan, Lemon, dan Suji
Abstrak: Green grass jelly is a functional food that has many beneficial healt effects, such as an anticancer. Traditional green grass jelly is susceptible to syneresis and of microbial contamination, resulting in a decrease in quality. Previous studies showed that the addition of carrageenan and NaHCO3 has resulted in pasteurized green grass jelly with exterded shelf life. The purpose of this study were to obtain the best formulation of green grass jelly with the addition of pandan, lemon, and suji extracts based on its physical and sensory properties, and to study its functional and microbiological characteristic. Jelly with 10% pandan extract and 5% lemon juice were known to have lower syneresis and was accepted by the panelist. Therefore, were selected as the best product. Lemon flavored jelly was better than pandan jelly in term of antioxidant and total phenol. The antioxidant capacity in green grass jelly with lemon juice was 0.5184 mg AEAC/g w.b and total phenol was 29.6407 mg GAE/g w.b. The antioxidant capacity of green grass jelly with pandan extract was 0.3375 mg AEAC/g w.b and total phenols was 21.9382 mg GAE/g w.b. However, pandan jelly contain a higher amount of chlorophyll (0.0230 mg/g w.b) than the lemon jelly (0.0185 mg/g w.b). Total plate count result showed the bacterial content was < 2,5 x 102 CFU/g, this value met the requirement of SNI that is < 1,0 x 104 CFU/g.
Keyword: antioxidants, pandan leave extract, lemon juice, green grass jelly

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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