Judul: Production of Dried Lactobacillus plantarum NHC6 Starter by Using Rice Bran Matrix
Abstrak: Starter Bakteri Asam Laktat (BAL) merupakan kultur BAL instan yang telah dipreparasi untuk menginisiasi produksi asam laktat dalam proses fermentasi. Pembuatan starter BAL membutuhkan media alternatif sebagai pengganti media MRS yang memakan banyak biaya bila digunakan untuk produksi skala industri. Starter kering memiliki keunggulan dibandingkan dengan starter cair. Untuk melindungi sel, diperlukan matriks enkapsulan yang berfungsi memberi pelindung bagi sel bakteri terhadap proses pengeringan yang dapat merusak sel. Diperlukan media yang baik dan mampu menjadi matriks enkapsulasi dalam pembuatan starter BAL kering. Bekatul dalam bentuk fraksi larut air panas terbukti mampu menjadi media pertumbuhan dan matriks enkapsulasi bagi Lactobacillus plantarum NHC6 dengan konsentrasi 10% menggunakan metode spray drying. Starter kering yang dihasilkan mengandung populasi Lactobacillus plantarum NHC6 sebanyak 1 x 107 CFU/g dan mampu mempertahankan viabilitas yang lebih baik pada penyimpanan suhu 4°C selama 28 hari masa penyimpanan. Berdasarkan keunggulan dan kemampuan mempertahankan viabilitasnya, starter Lactobacillus plantarum NHC6 kering dengan matriks bekatul berpotensi menjadi produk pangan probiotik nonsusu.
Keyword: LAB, rice bran, dried starter, encapsulation, probiotic

Judul: Seleksi Bakteri Asam Laktat dan Pemanfaatannya sebagai Starter Kering Menggunakan Matriks Tapioka Asam
Abstrak: Starter is a microbial preparation that will be added to the raw materials in production of fermented food products. It is used to accelerate the fermentation process and reduce the risk of failure during the fermentation. Although starter cultures could be in the liquid or dry forms, the dried culture is more advantageous due to its long stability without regenerated. The most widely used bacteria for starter cultures production is lactic acid bacteria (LAB). LAB as a starter should be safe for other natural microorganisms in human body and has a high fermentation productivity. Therefore, the strains selection of LAB which would be used as a starter is important to do. The important criterias for LAB selection are the ability of producing lactic acid and antibiotic sensitivity. LAB should also have a high cell viability after the drying process and during storage, meaning that drying techniques and proper matrix are also pivotal factors to produce a desirable starter cultures. Sour cassava starch is a modified starch which is produced from fermented tapioca. This material has promising properties for LAB encapsulation matrix because it is prepared using LAB-induced fermentation, and does not contain food chemical additives as well as contain fermented monosaccharides which can act as a protective agent (protectant) during drying and storage. Raw materials of sour cassava starch are widely available, economical and renewable. The aims this study were to produce LAB dried starter using sour cassava starch matrix and to study its viability after storage. Eleven local LAB isolates obtained from spontaneous fermentation of carbohydrate commodity were selected based on their acid production ability and antibiotic sensitivity. The initial selection of the acid production ability was conducted by measuring the total acid and pH level of culture media. The isolate sensitivity to antibiotics tetracycline, erythromycin and chloramphenicol were tested by disc diffusion method. The isolate that produce high level of acid and is vulnerable to antiobiotics was selected and subsequently evaluated its lactic acid production using high performance liquid chromatography (HPLC). The isolate that have a higher production of lactic acid was choosen for this study. Furthermore, its morphological character and growth curve were observed. Morphological characters have been observed using a light microscope including Gram staining and cell shape observation. Growth curve was observed by calculation of cell numbers (log CFU/mL) while the optical density (OD) using a spectrophotometer at a wavelength (λ) 620 nm. Cell numbers was calculated using total plate count (TPC) on de Man Rogosa Sharpe agar (MRSA) medium were incubated at 37°C for 48 hours. Observation was conducted every hour until the cells reached a maximum specific growth rate (μm,h-1). Dried starter of selected isolate was produced using freeze dryer (-50oC) and spray dryer (inlet 170°C, outlet 70°C). The matrix used was sour cassava starch and sour cassava starch enriched with 10 % skim milk were used as the positive control. Starter has been stored in an airtight aluminum foil for water content analysis (%), cell viability (log CFU/g) and survival rate (%) after drying. Storage stability of the best starter was evaluated in four
Keyword: dried starter, lactic acid bacteria, sour cassava starch, freeze drying, spray drying

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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