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: Produksi Kopi Secara Enzimatis Menggunakan Bakteri Proteolitik dan Kombinasi Bakteri Selulolitik dan Xilanolitik Dari Luwak
Abstrak: Civet coffee is a commercial coffee produced from in vivo by civet. The production of civet coffee is rely on the availability and sustainability of civet life cycles. The purpose of this research was to produces civet like coffee by solid substrate fermentation. Coffee pulp (60 mesh) used as a media growth of bacteria and produced enzyme which used by coffee beans. The substrate of fermentation added inoculum at 10% (wet basis) and fermented for 4 days at 30oC and 37oC. Inoculum using a single bacteria (proteolytic), a mix between cellulolytic and xylanolytic bacteria, and a mix between proteolytic, cellulolytic, and xylanolytic bacteria. Data measured were reducing sugar, total sugar, protein content and enzyme activity daily. Coffee beans from the best fermentation for each treatment analyzed by HPLC. Fermentation using proteolytic bacteria shown best performance at 37oC for one day incubation, fermentation using a mix cellulolytic and xylanolytic bacteria at 30oC after three days incubation and the combination of three bacteria similar to using combination of two bacteria. Quality of fermented coffee based on organic acids and caffeine content equivalent to the original civet coffee. For all treatments was lower caffeine contents than civet coffee. Organic acids in fermented coffee shown higher lactate, butyrate, and ascorbate acids and lower oxalate acids. Fermented coffee has a better nutrition contents than original civet coffee.
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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