Judul: Fermentasi Kopi Menggunakan Bakteri Xilanolitik dari Luwak
Abstrak: Civet coffee is a coffee produced by civet and come out with feces. One of the predominant microorganisms involved for civet fermentation is xylanolitic bacteria. This study was aimed to select the best xylanolitic bacteria and use it in the fermentation. The xylanolitic bacteria has been tested and identified as Agrobacterium tumifaciens and Stenotrophomonas sp. However, these experiments use only Agrobacterium tumifaciens because it has higher enzyme activity than Stenotrophomonas sp. The fermentation was held at 30, 40, and 50oC for five days. The enzyme activity, shrinkage weights, levels of carbohydrate and protein content were tested daily. The second and third day of fermentation at 30 and 40oC showed a relative higher decrease of shrinkage weight and carbohydrate content. It suggests a good fermentation conditions for civet coffee production. The organic acid in the coffee were analyzed by HPLC (High Performance Liquid Chromatographic). The oxalic acid, lactic acid, ascorbic acid and caffeine content of the experiment were lower whereas the butyric acid was higher than the civet coffee. The experiment fermentation gave a better quality coffee product than civet coffee.
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Judul: Fermentasi Biji Kopi Menggunakan Bakteri Selulolitik, Xilanolitik dan Proteolitik Asal Luwak
Abstrak: Civet coffee is fermented coffee which is produced naturally in the digestive tract of mongoose. The production of civet coffee is relied on the availability of the civet, therefore the production is costly. This research aim was to produce synthetic civet coffee by enzymatic fermentation.The enzymes were produced by cellulolytic, xylanolytic, and proteolytic bacteria that were isolated from civet feces. The combination treatment was examined the highest enzymatic production from different bacteriawiththe variation oftemperature during four days. During the fermentation, the produced enzymes were used for hidrolize the substrate. Enzymatic process was determined by changing the total and reducing of sugar, weight losses, protein content and the enzyme activity produced in the substrate. The fermentation was done by cellulolytic bacteria and combination of threebacteria. Alltreatment were resulledan approximate similarcaffein reduction (48%), however the nutrition content indicated by organic acid were shown that thecoffee fermentation has a low oxalic acid and higher butyric, lactic and ascorbic acid.
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Judul: Simulasi persamaan keadaan bintang dengan pendekatan klasik dan relativistik
Abstrak: Komposisi bintang yang selalu berubah akanmempengaruhi massa dan radius bintang itu sendiri. Dimana semakin tua sebuah bintang, maka bintang akan didominasi oleh unsur-unsur berat. Dengan persamaan politrop dan metode Runge-Kutta orde 4 didapatkan radius dan massa bintang semakin berkurang seiring berkurangnya nilai Ye, sedangkan kerapatan semakin meningkat. Pendekatan terbaik terdapat pada nilai Ye sebesar 0.5 dimana didapatkan bahwa massa bintang katai putih sebesar 1.4Mo sesuai dengan massa Chandrasekhar dengan radius bintang 5000 km dan nilai kerapatan bintang sebesar 5.31x 106 g cm-3. Untuk massa bintang neutron diperoleh nilai 0.05Modan radius bintang sebesar 2300 km, sedangkan kerapatannya bintang neutron diperoleh sebesar 1.84 x 107 g cm-3 dengan menggunakan pendekatan relativistic. Pendekatan relativistic terbukti lebih baik untuk menentukan radius dan massa bintang, dengan pendekatan terbaik pada nilai Ye sebesar 0.5 yaitu pada bintang katai putih
Keyword: Composition of the stars, density of the stars, mass of the stars, radii of the stars