Judul: Produksi Xilitol dari Hidrolisat Limbah Tandan Kosong Sawit oleh Candida tropicalis.
Abstrak: Limbah padat terbesar yang dihasilkan dari perkebunan kelapa sawit salah satunya adalah tandan kosong kelapa sawit (TKKS). Limbah tersebut hingga saat ini dimanfaatkan sebagai pupuk organik namun pemanfaatan tersebut belum maksimal. Limbah TKKS dengan komponen utama hemiselulosa, selulosa, dan lignin dapat dihidrolisis menjadi xilosa dan dikonversi menjadi produk xilitol yang memiliki nilai jual tinggi. Xilitol merupakan gula alkohol yang memiliki manfaat untuk mencegah kerusakan gigi, memiliki nilai kalori dan nilai glikemik yang rendah sehingga aman bagi penderita diabetes. Penelitian ini bertujuan untuk memproduksi xilitol dari limbah TKKS dengan pemberian arabinosa sebagai kosubstrat pada sel Candida tropicalis. Xilosa dihidrolisis secara kimiawi menggunakan asam dan rendemen yang dihasilkan diukur dengan metode DNS, nilai rendemen xilosa tertinggi yaitu 4.93%. Xilitol yang dihasilkan diukur dengan ELISA Reader menggunakan kit D-sorbitol Colorimetric Assay pada panjang gelombang 540 nm dan waktu inkubasi selama 30 menit. Kadar xilitol tertinggi yang dihasilkan pada sampel TKKS sebesar 13.559%. Penambahan ko-substrat arabinosa tertinggi diperoleh pada arabinosa 5% di waktu fermentasi 8 jam.
Keyword: Arabinosa, C. tropicalis, tandan kosong kelapa sawit, xilitol

Judul: Xylitol Production from Sugarcane Bagasse Hydrolysate by Immobilized Cell Candida tropicalis and Candida guilliermondii.
Abstrak: Xilitol merupakan gula alkohol berkarbon lima yang banyak digunakan di bidang farmasi, kesehatan, dan pangan. Xilitol mempunyai harga tinggi tetapi ketersediaan xilitol dalam perdagangan masih rendah. Produksi xilitol secara komersial masih memiliki hambatan yaitu biaya produksi mahal, karena diperlukan energi yang tinggi (proses hidrogenasi) dan bahan baku xilosa murni. Oleh karena itu dibutuhkan teknik produksi alternatif yang lebih murah dengan memanfaatkan mikroba dan hidrolisat ampas tebu. Penelitian ini bertujuan mengoptimasi produksi xilitol dengan amobilisasi sel Candida tropicalis dan Candida guilliermondii serta pengaruh penambahan nutrien pada media hidrolisat ampas tebu. Fermentasi dilakukan pada suhu 30oC dengan kecepatan pengadukan 120 rpm. Pengukuran kadar xilitol ditentukan dengan metode spektrofotometer menggunakan kit D-sorbitol/D-xilitol pada panjang gelombang 492 nm. Hasil penelitian menunjukkan teknik amobilisasi sel mampu meningkatkan hasil produksi xilitol yaitu pada jam ke 96 diperoleh kadar xilitol 12.28 g/L untuk sel amobil dan 10.84 g/L untuk sel bebas. Sel Candida tropicalis menghasilkan produk xilitol lebih tinggi dibanding Candida guilliermondii. Kadar xilitol yang dihasilkan sel amobil Candida tropicalis diperoleh sebesar 12.28 g/L dari konsentrasi xilosa 30 g/L dan sel amobil Candida guilliermondii diperoleh 2.8 g/L. Perlakuan penambahan nutrien ekstrak khamir diperoleh kadar xilitol sebesar 17 g/L dan penambahan nutrien KH2PO4 menghasilkan kadar xilitol tertinggi, yaitu 20.31 g/L dan nilai rendemen 0.68 g/g.
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Judul: Exchange Market Pressure and Central Bank Intervention for Three ASEAN Countries
Abstrak: Two of the exchange rate systems which are adopted by many countries are the floating and the fixed exchange rate system. Both the exchange rate systems have different characteristics. Countries that implement fixed exchange rates system tend to set their domestic currency exchange rate at a certain point. On the contrary, countries which implement floating exchange rate system tend to let their domestic currency exchange rate to move flexibly and thus their value will always change according to the demand and supply of the currency in the foreign exchange market. Countries which implement floating exchange rate system are facing the risk of fluctuation in the exchange rate of their domestic currency against foreign currencies. The currency exchange rate fluctuation may be caused by economic problems such as a financial crisis. A country can also be potentially affected by other countries’ earlier financial crisis. This effect could potentially happen if these countries are in the same region, such as ASEAN. The 1997 ASEAN economic crisis was an example of a country’s financial crisis could affect other countries. At that time, some countries such as Indonesia, Malaysia and Thailand had to change their currency exchange rate system from the fixed exchange rate system to the floating exchange rate system due to the high costs which has to be incurred if they were to enforce the fixed exchange rate system. During 2002 until 2012, the domestic exchange rate of Indonesia, Malaysia and Thailand against the U.S. dollar had tended to fluctuate. If the domestic currency exchange rate fluctuated excessively then the central bank would intervene to stabilize the exchange rate in the foreign exchange market. The pressure on domestic currency exchange rate pressures has forced the central bank to intervene. The amount of those pressures can be analyzed by calculating the Exchange Market Pressure (EMP) index. Apart from that, the time when interventions are done by the central bank can be known based on EMP by calculating the Exchange Market Intervention (EMI) index. The purposes of this study were to determine the level of international pressure on the currency exchange market and monetary authorities intervene in three ASEAN countries, as well as to determine the effect of the monetary authorities intervene on the exchange rate of the domestic currency against the U.S. dollar in those three ASEAN countries. Based on the EMP index calculation results which are obtained during 2002 to 2012 period, the exchange rate of Indonesia, Malaysia and Thailand’s domestic currency had always fluctuated and the results of the EMP index indicated that each country were under diverse level of currency exchange rate appreciation and depreciation pressures. Thailand was the country with the highest currency exchange rate pressure compared to Indonesia and Malaysia. The results on the intervention index calculation showed that Indonesia, Malaysia and Thailand have intervention index between zero and one and more than one. We can also see from the intervention index that Indonesia and Thailand implement the controlled floating currency exchange rate instead of the freely floating one. Based on the calculation of the currency exchange rate by comparing
Keyword: exchange rate, exchange market pressure, intervention