Judul: Hidrolisis Pati Umbi Tacca Menggunakan Ekstrak Kasar α-Amilase dari Brevibacterium sp. untuk Menghasilkan Oligosakarida
Abstrak: Oligosaccharides have an important function in various sectors such as healthcare, industrial, food and feed, including as functional food ingredients (prebiotics). Oligosaccharides were produced from Tacca tubers (Tacca leontopetaloides) which containing 66.65 % of starch. Tacca tubers were used from Hutan Jati, and enzymes were used α-amylase from Brevibacterium sp. which has enzyme activity of 1.78 U mL-1 . The purposes of this research are to determine the optimum conditions Tacca tuber starch hydrolysis reaction and determine the type of oligosaccharides using Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). Optimal production was achieved at 3 % substrate concentration, enzyme and substrate ratio of 1:5 and hydrolysis time of 6-8 hours. Oligosaccharides profile analysis both using TLC and HPLC showed that the enzimatically hydrolyzed samples contained maltose, maltotriose and maltotetraose.
Keyword: High Performance Liquid Chromatography (HPLC), Thin Layer Chromatography (TLC), maltooligossacharides, Brevibacterium sp., Tacca tubers

Judul: Produksi Oligosakarida dari Umbi Kentang Hitam melalui Hidrolisis Ekstrak Kasar α-Amilase asal Brevibacterium sp.
Abstrak: Oligosaccharides is a carbohydrate macromolecule composed of 2-10 monosaccharide residues that have benefits in the field of food and health. One way to produce oligosaccharides with enzymatic hydrolisis of starch. Black potatoes have high carbohydrate content, especially starch by 83%. Activity of amylase enzyme from raw extraction have 1.708 U/ml. Degree of polymerization of black potatoe’s starch is 10. Hydrolysis reaction of black potatoe’s starch with that enzyme gave 3 spots on TLC analysis with mobile phase n-buthanol:acetic acid:water purified (2:1:1). In HPLC analysis showed 3 main peaks that means consist of 3 compound with mobile phase acetonitrile:water (75:25). Fresh sample consist of glucose as many as 1,60% (b/v), maltose 0,36% (b/v), and maltotriose 0,46% (b/v). Freeze dried sample consist of glucose as many as 4,20% (b/v), maltose 0,21% (b/v), and maltotriose 0,30 % (b/v).
Keyword: Brevibacterium sp., α-amylase enzyme, HPLC, oligosaccharides, black potatoes

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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