Judul: Assessment of current hygienic manufacturing practices and evaluation of additional food preservatives effect in Nam Prik Mushroom
Abstrak: Nam Prik Mushroom is ready-to-eat food product in Thailand which made from edible mushroom Schizophyllum commune with curry paste. It is produced by Chaiyo Farm, one of Thailand small-medium enterprise. Current hygienic and manufacturing practices in Chaiyo Farm and effectiveness of combination chemical food preservatives, propyl-paraben and calcium propionate, of Nam Prik Mushroom’s shelf life was assessed. Assessment of manufacturing practices at Chaiyo Farm resulted in total conformity of 25.83% based on Thailand Primary Good Manufacturing Practices. Propyl-paraben and calcium propionate did not influence pH, color, and water activity of Nam Prik Mushroom. The effectiveness combination of propyl-paraben and calcium propionate to extend the shelf life Nam Prik Mushroom was not proven. Either non-preserved or preserved Nam Prik Mushroom could not be accepted organically after 3 days storage at room temperature.
Keyword: Bogor Agricultural University (IPB), shelf life, Schizophyllum commune, calcium propionate, propyl-paraben, GMP

Judul: Pengemasan atmosfer termodifikasi pada jamur merang (Volvariella volvacea) blansir
Abstrak: Straw mushroom has a shelf life of 12 hours if left at room condition. This condition can be fixed by modified atmosphere packaging (MAP) application. The aim of this research was to obtain the best package design for modified atmosphere packaging of blanching straw mushroom. Before packaging, mushrooms treated blanching using hot water that serves to reduce the possibility of oxidation reactions. The addition of preservative aims to slow and inhibit the browning process of destructive microorganism, slow down, cover up or withhold the process of fermentation, putrefaction, acidification or other decomposition of destructive microorganism. Design of the package consisted of package size, number of perforation, and diameter of perforation. This research was also aimed to determine the best storage temperature. The parameters that observed during storage time were weight decrease, hardness, whiteness level, and the level of distortion. Each treatment had different perforation number and storage temperature. Perforation number that observered were 2, 4 and 8. Perforation diameter that used was 5 mm. While storage temperature that used were 5°C, 15°C, and 25°C. Each treatment made to twice repetition and stored for 14 days. The analysis done every 2 days. Every broken sample was not physically analyzed. During storage time weight, hardness, color, and quality decrease of straw mushroom is had happened thoroughly. Each package treatment had different effect on measured parameter. The result showed that package design of polypropylene plastic bag with 4 perforations and 5 mm perforation diameter that storaged in 15°C temperature was the best design to pack fresh straw mushroom. This package design was able to maintain mushroom quality for 10 days long, whereas other treatments were only able to maintain mushroom quality less than 10 days long. That package design was able to create optimum atmosphere compotition to pack mushroom so metabolism rate could be suppressed. Else, low storaging temperature could also suppressed metabolism rate as well as inhibited the growth of destructive microorganism. The result of mushroom measuring in that package at 10th day were weight decrease of 19:22%, hardness of 12.53 mm, whiteness level of 68.9, the level of damage by 38.49%. The damage indication that suffered by straw mushroom so it unable to consume were mushroom changed in color to brown, flabby and had decomposed smell.
Keyword: 

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