Judul: Karakterisasi Gel Cincau Hijau Kemasan Selama Penyimpanan Dingin
Abstrak: Green grass jelly without heat treatment has a very short shelf life, which is one day if stored at ambient temperature. In the previous research, green grass jelly with addition of hydrocolloid had been made to maintain its physical characteristic after heat treatment. The objective of this research is to study the characteristic of pasteurized (CHP) and steamed (CHK) green grass jelly at cool storage (5-10oC) for 15 days. The product had been analyzed for its physical (gel strength, colour, syneresis rate, and pH value), microbiological (TPC), and functional properties (total chlorophyll, phenolic compound, antioxidant capacity, dietary fiber) every three days. The result showed that CHP and CHK commonly have similar pattern of changes, which had increased in syneresis rate, dietary fiber, and total microbes, whereas green colour intensity, pH value, total chlorophyll, total phenolic compound, and antioxidant capacity decreased after stored within 15 days. In the end of storage period, syneresis rate of CHP (6,66%) was higher than CHK (4,90%). pH value were relatively stable during storage for both products. CHK had higher green colour intensity (a* value more negative) than CHP, which prominently showed at the beginning of storage. All functional properties of CHP and CHK slightly decreased during storage. CHK complied SNI 7388:2009 without storage, while CHP complied SNI until 12 days of storage.
Keyword: pasteurization, steaming, cool storage, green grass jelly

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: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix