Judul: Produksi bioetanol dari empulur sagu menggunakan enzim dan khamir dari isolat lokal
Abstrak: Starch and fiber from Sago palm can be used for making bioethanol. Starch are accumulate in the pith core of sago palm steam. The pith was pretreated with conventional heating (autoclaving) or microwave. After pretreatment, the sago pith was hydrolysed using α-amylase at 95 oC. The saccharification of sago pith was conducted using consortia of three enzymes (amyloglucosidase, cellulase and xylanase) at 60 o C. Hydrolysis of sago pith was done with these commercial starch degradating enzymes and self-prepared enzymes from local isolates of cellulolytic and xylanolytic bacteria. Yeast used at the fermentation process was isolated from rotten fruits. Selection of yeast was based on their ability to consume mixed substrates of xylose and glucose; and the ethanol production. After 72 hours of fermentation the ethanol production was analyzed using Gas Chromatography. Ethanol produced from conventional heating was greater than microwave heating by using yeast isolate MP (8.11%).
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Judul: Sakarifikasi Empulur Sagu (Metroxylon sagu) dengan Konsorsium Enzim Amilolitik dan Holoselulolitik untuk Produksi Bioetanol
Abstrak: Starchy materials such as sago in bioethanol production is one effort in finding solutions to the depletion of fossil fuel reserves but leaving a large amount of wastes. In this research, native sago pith was used directly for bioethanol production. Sago pith is heterogeneous substrates that need pretreatment to reduce the level of crystallinity of fibers and dissolve the starch; also required a number of enzymes to hydrolyze. This research aim is to determine the effects of microwave treatment and consortia of enzymes (α-amylase, amyloglucosidase and pullulanase, cellulase and xylanase) in fermentable sugar production process from the pith of sago palm and its utilization for bioethanol production. This study included the preparation of raw materials sago pith, pith composition analysis including proximate components, starch, amylose and the composition of fiber (cellulose, hemicellulose, and lignin), characterization and preparation of enzymes for determining the optimum temperature, the process of hydrolysis and characterization of syrup. Furthermore, the results of hydrolysis are used in the production of bioethanol in batch and closed systems. The results showed that, microwave treatment made starch easy to swell and break the crystalline structure of fiber. Enzymes consortia in saccharification increased the fermentable sugar production but S. elippsoides used tend to convert glucose into organic acids in spite ethanol.
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Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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