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: Potensi Enzim -Galaktosidase dari Lactobacillus plantarum Strain B123 Indigenous untuk Hidrolisis Laktosa pada Susu UHT
Abstrak: Lactose concentration in milk is 4.6% (w/w) in average (Walstra 2006). The content of lactose with less than 1% (w/w) of final product is acceptable for people with lactose intolerance problem (Tuure and Corpela 2004). Enzymatic hydrolysis of lactose is one of the important biotechnological processes in the milk industry because of some beneficial effects including the elimination of lactose in milk for people with lactose intolerance, prevention of lactose crystallization and contribution to the product sweetness (Jurado et al, 2002). -Galactosidase enzyme can be produced by lactic acid bacteria. In this study, indigenous Lactobacillus plantarum strain B123 was isolated from Indonesian traditional fermented vegetable product. The use of this local potential strain was to increase its role to the added value products such as low lactose UHT milk. Even though low lactose UHT milk product has not been commercially marketed yet in Indonesia, however the need of low lactose milk for people with lactose intolerance was already present. This research was aimed to: (1) determine the growth condition of indigenous Lb. plantarum strain B123 to produce β-galactosidase (2) determine the production condition of -galactosidase from Lb. plantarum B123 strain with partial purification and (3) determine the potential of β-galactosidase from indigenous Lb. plantarum B123 strain to hydrolyze lactose of full cream and low fat-UHT milks, containing total fat 3.5 and 1.0% (w/v) respectively, in batch process. The result showed that the growth condition of indigenous Lb. plantarum B123 in MRSB to produce β-galactosidase were 2% inoculum, 1% of lactose, medium pH 8, and 24 h incubation time at 37°C. The enzyme showed an optimum activity to hydrolyzed oNPG substrate at pH 6.5 and temperature 50°C . Specific activity of -galactosidase has increased during the partial purification given 15.05 U/mg in crude enzyme to 109.58 U/mg in dialysed enzyme (at first production) and 87.09 U/mg in crude enzyme to 109.58 U/mg in dialysed enzyme (at second production). Lactose in full cream-UHT milk was hydrolyzed at a maximum rate of 60.0% (lactose concentration from 3.82% w/v to 1.52% w/v) and in low fat-UHT milk 81.1% (lactose concentration from 4.44% w/v to 0.84% w/v) by 7.2 U β-galactosidase/mL milk for 9 h at 50°C. Enzyme concentration, hydrolysis time and total fat concentration had a significant influence on the hydrolysis of lactose in UHT milk (p<0.05). According to the different analytical methods to monitor the lactose hydrolysis, a correlation between the results of glucose concentrations in full cream-UHT milk analyzed by GOD-POD kit and HPLC was observed. There was a positive correlation between analysis of glucose concentrations in full cream-UHT milk with GOD-POD kit and HPLC (r = 0.923).
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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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