Judul: Amobilisasi Sel Lactobacillus plantarum B134 dan β-Galaktosidase dengan Natrium Alginat dan Potensi Hidrolisisnya pada Susu UHT Skim dan Berlemak
Abstrak: Susu merupakan salah satu produk pangan yang memiliki nilai gizi yang baik. Sayangnya, konsumsi susu Indonesia hanya 11.09 per liter per kapita per tahun. Minimnya konsumsi susu dapat disebabkan karena intoleransi laktosa yaitu ketimakmampuan tubuh untuk mencerna laktosa karena tidak memiliki β-galaktosidase. Solusi alternatifnya adalah mengolah susu sampai kadar laktosanya menjadi rendah menggunakan β-galaktosidase dari mikroorganisme. L. plantarum B134 merupakan bakteri asam laktat dari Indonesia yang memiliki aktivitas β-galaktosidase yang tinggi. Penggunaan β-galaktosidase lebih efisien apabila dilakukan teknik penjebakan (amobilisasi) sehingga dapat digunakan berulang dan dapat menurunkan biaya produksi. Natrium alginat merupakan matriks penjebak yang murah dan aman untuk mengamobilisasi enzim dan sel. Penelitian ini bertujuan untuk menghidrolisis laktosa susu UHT berlemak dan skim dengan menggunakan sel L. plantarum B134 amobil dan β-galaktosidase amobil. Tahapan penelitian ini meliputi (1) optimasi amobilisasi sel L.plantarum B134 dan β-galaktosidase dengan natrium alginat, (2) pengaruh pH dan suhu pada sel L.plantarum B134 dan β-galaktosidase amobil, (3) stabilitas pH dan suhu β-galaktosidase amobil, (4) hidrolisis laktosa pada susu UHT berlemak dan skim, (5) keterulangan pemakaian beads sel L. plantarum B134 amobil dan β-galaktosidase amobil, dan (6) penyimpanan β-galaktosidase amobil. Sel L. plantarum B134 amobil mencapai optimum pada 1% natrium alginat, 0.1 M CaCl2, dan 12% b/v sel. Aktivitas β-galaktosidase mencapai optimum pada pH 6.5 dan suhu 45ºC selama 5 menit. Efisiensi amobilisasi sel L. plantarum B134 amobil adalah 28.95%. Laktosa susu UHT berlemak terhidrolisis sebesar 85.45% selama 12 jam sedangkan pada susu UHT skim sebesar 91.26% selama 9 jam. Sel L. plantarum B134 amobil dapat digunakan untuk kedua tipe susu UHT sebanyak 4 kali. β-Galaktosidase amobil mencapai optimum pada 1% natrium alginat, 0.1 M CaCl2, dan 26 U β-galaktosidase. Aktivitas β-galaktosidase amobil mencapai optimum pada pH 5.5, suhu 35ᵒC selama 15 menit. Efisiensi amobilisasi β-galaktosidase amobil adalah 96.69%. Stabiltas pH tercapai pada pH 5 dan stabilitas suhu pada 30ºC. Nilai Km dan Vmaks β-galaktosidase masing-masing sebesar 30.487 mM dan 1.742 μmol/menit. β-Galaktosidase amobil mereduksi 80.55% laktosa UHT belemak selama 15 jam dan 93.06% laktosa UHT skim selama 6 jam. β-Galaktosidase amobil dapat digunakan 3 kali untuk hidrolisis laktosa susu UHT berlemak dan 6 kali untuk susu UHT skim. Setelah penyipanan 35 hari pada suhu 4ºC, β-galaktosidase masih memiliki aktivitas relatif β-galaktosidase sebesar 52.01%.
Keyword: amobil, β-galaktosidase, Lactobacillus plantarum B134, natrium alginat, UHT

Judul: Amobilisasi β-galaktosidase Bakteri Asam Laktat Indigenos Strain D-210 dengan Natrium Alginat dan Potensi Hidrolisisnya pada Susu UHT
Abstrak: Lactose intolerance is a symptom who cannot produce the β-galactosidase enzyme (lactase) an enzyme that catalyzes hydrolysis of lactose into glucose and galactose, in their digestive system. In most cases this causes symptoms which may include abdominal bloating and cramps, flatulence, diarrhea and nausea. Immobilization of Indigenous Lactic Acid Bacteria strain D-210 β-galactosidase with natrium alginate and its potential in UHT milk has not been reported yet. Indigenous Lactic Acid Bacteria strain D-210 was found as bacteria producing β-galactosidase which was culture in MRS (Mann Rogosa Sharpe) and substrate lactose 3%. The β-galactosidase was dialyzed for getting the partial pure. The research results showed that the optimum production of β-galactosidase in Indigenous Lactic Acid Bacteria Strain D-210 was reached on 24 hours with activity 26.605 U/ml and total activities was 27.669 U, and Indigenous Lactic Acid Bacteria Strain D-210 optimum growth was reached on 24 hours with optimum optical density 1.984 and amount of cell was 1.81x10-8 cell/ml. The total activities partial purification of crude β-galaktosidase was 138.396 U, total activities after presipitation with amonium sulfat the total activities was 87.030 U and total activities after dialysis was 50.420 U. The inhibitors of β-galaktosidase were Hg and Cu with relative activities were 56.82% and 1.04%, while the activators were Mg,Mn,Ca,Co,Zn. Kinetic parameter of enzyme showed that the values of Km: 0.491 mM and Vmax:0.093 μmol/minute (free β-galactosidase), and values of Km:15.54 mM and Vmax 0.474 μmol/minute (immobilized β-galactosidase) . The optimum activity of the free β-galactosidase was reached on pH: 6.5 with activity 252.341 U/ml, and temperature: 45 oC with activity 180.093 U/ml. The optimum concentration of Na alginate for immobilized cell and β-galactosidase were 2% and 3% respectively. The concentration of Na alginat used for hydrolysis lactose in cell was 12% with the released total product 58.884 μmol and for the β-galactosidase was 20% with the released total product 91.752 μmol. The optimum activity of the immobilized β-galactosidase was reached on pH:6 with activity 40.428 U/ml, and on temperature: 40 oC with activity 41.194 U/ml. The optimum potential of cell imobilized and β-galactosidase for lactose hidrolysis in UHT milk were reached for 6 hours and 18 hours with relative activity 76.72% and 62.78% respectively. Repeated use of cell and enzyme β-galactosidase immobilized was 6 times with the use of relative hydrolisis activity were 39.52% and 53.68% respectively.
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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