Judul: Aplikasi Enzim Laktase Terimobilisasi dengan  Alginate Beads untuk Penurunan Kadar Laktosa pada Susu
Abstrak: Susu mengandung jenis gula yang spesifik yaitu laktosa. Terdapat beberapa kalangan yang tidak dapat mengonsumsi susu dan produk turunannya karena mengidap intoleransi laktosa. Salah satu cara untuk menurunkan kandungan laktosa dalam susu adalah memecah laktosa menjadi glukosa dan galaktosa dengan bantuan enzim laktase. Metode penurunan kadar laktosa yang digunakan pada skala industri adalah metode enzim terlarut yang dinilai tidak efisien karena memerlukan enzim laktase baru di setiap batch produksi. Metode imobilisasi enzim menjadi salah satu metode yang dapat diterapkan untuk mengefisienkan penggunaan enzim laktase. Penelitian ini bertujuan mengkaji penggunaan metode imobilisasi enzim laktase dengan manik alginat pada proses penurunan kadar laktosa dalam susu, mengkaji pengaruh perlakuan terhadap aktivitas dan stabilitas enzim serta karakteristik sensori susu. Penelitian dilakukan menggunakan Rancangan Acak Lengkap Faktorial (RALF) dengan 2 faktor yaitu konsentrasi enzim (0,1% dan 0,2%) dan waktu inkubasi (24 jam dan 38 jam). Hasil penelitian menunjukkan bahwa setiap kombinasi faktor perlakuan menghasilkan kadar laktosa yang berbeda mulai dari 2,79%-3,35%. Aktivitas enzim laktase terimobil juga mengalami penurunan setelah pemakaian berulang karena terdapat enzim laktase yang terlepas dari matriks Ca-alginat. Hasil uji sensori menunjukkan bahwa perlakuan yang dilakukan selama proses penurunan kadar laktosa dengan metode imobilisasi enzim berpengaruh secara signifikan terhadap atribut rasa, tekstur, dan keseluruhan susu., Milk contain specific type of sugar which is lactose. There are some people who cannot consume milk and its derivative products because they suffer from lactose intolerance. One way to lower the lactose content in milk is to break down lactose into glucose and galactose with the help of the lactase enzyme. Method of reducing lactose content that usually use in industrial scale is dissolved enzyme method which considered inefficient because it requires a new enzyme in each batch of production. The enzyme immobilization is one method that can be applied to efficiently the use of lactase enzyme. This study aimed to simulate the application of lactase enzyme immobilization with alginate beads in the process of reducing lactose content in milk, assessing the effect of treatment on enzyme activity and stability as well as sensory characteristic of milk. The study was conducted using Factorial Complete Randomized Design (RALF) with 2 factors, namely enzyme concentration (0.1% and 0.2%) and incubation time (24 hours and 38 hours). The results showed that each combination of treatments produced different lactose levels ranging from 2.79%-3.35%. Repeated use of immobilized lactase enzyme can decrease its activity because there is a lactase enzyme released from the Ca-alginate matrix. The results of sensory tests show that the treatment carried out during the process of reducing lactose content with the enzyme immobilization method has a significant effect on the taste, texture, and overall attributes of milk.
Keyword: enzim laktase, imobilisasi enzim, laktosa, manik alginat, susu, alginate beads, enzyme immobilization, lactase enzyme, lactose, milk

Judul: Optimization of Lactase Enzyme Immobilization in Alginate Beads with I-Optimal Design for Low Lactose Milk Production
Abstrak: Susu merupakan sumber protein hewani yang mengandung komponen gizi yang lengkap dan kompleks. Penderita intoleransi laktosa tidak mampu mengonsumsi susu yang mengandung laktosa karena tidak adanya enzim laktase dalam sistem pencernaannya untuk menghidrolisis laktosa menjadi glukosa dan galaktosa. Konsumen lactose intolerance dapat mengonsumsi laktosa dengan memecah terlebih dahulu laktosa yang ada dalam produk susu dengan menggunakan enzim laktase. Imobilisasi enzim dengan metode entrapment (penjebakan) menggunakan matriks alginat dan garam kalsium dibuat untuk memproduksi susu rendah laktosa yang ekonomis dalam industri pangan. Tujuan penelitian ini adalah (1) Mengkaji pengaruh dari garam kalsium yang berbeda dan konsentrasinya terhadap karakteristik matriks/beads Ca-alginat penjebak enzim laktase dan dampaknya terhadap kualitas susu rendah laktosa yang dihasilkan, (2) Mengkaji pengaruh dari perbedaan konsentrasi enzim laktase tehadap susu rendah laktosa yang dihasilkan, dan (3) Menentukan perlakuan terbaik susu rendah laktosa yang disukai konsumen. Penelitian ini dilakukan dua tahapan. Penelitian tahap pertama adalah pengujian bahan baku alginat, dan susu segar, meliputi pengujian kadar air, kadar abu, kadar glukosa, dan kadar laktosa. Pada Tahap kedua yang dilakukan adalah pembuatan beads alginat + laktase dengan optimasi response surface methodology (RSM), meliputi: (a) penentuan faktor optimum, besaran campuran, dan respon optimum, (b) pencampuran kombinasi level faktor yang diberikan oleh softwere design expert dan analisis kekuatan (hardness), kadar glukosa, laktosa, sensori, dan karakteristik beads alginat + laktase, (c) pencarian solusi terbaik (kombinasi optimal) campuran bahan baku. Penelitian dilakukan dengan metode response surface methodology (RSM) dengan perbedaan konsentrasi garam kalsium (0,1; 0,2; dan 0,3M), konsentrasi enzim laktase (4; 6; dan 8 mg/ml), dan jenis garam kalsium yang digunakan (kalsium klorida dan kalsium laktat) menghasilkan 19 perlakuan. Kemudian dilakukan uji verifikasi susu rendah laktosa perlakuan optimum. Pengolahan data pada penelitian ini menggunakan RSM dan SPSS. Hasil analisis bahan baku pada alginat dengan kadar air sebesar 12,57% (bb) dan kadar abu sebesar 22,42% (bb). Hasil analisis bahan baku pada susu segar pasteurisasi didapatkan kadar glukosa sebesar 0,07% dan kadar laktosa sebesar 3,83%. Perlakuan optimum yang didapat dari metode mixture design adalah 0,189M konsentrasi garam kalsium laktat dan 8mg/ml konsentrasi enzim laktase. Hasil analisis fisikokimia perlakuan optimum menunjukkan memiliki nilai kekerasan 0,0223Pa, kadar glukosa 4,94%, kadar laktosa 1,36%, dan nilai uji sensori 6,6. Hasil verifikasi menunjukkan perlakuan optimum berada dalam rentang (95% CI dan 95% PI). Hasil sensori menunjukkan perlakuan optimum lebih disukai konsumen dengan skor rasa dan keseluruhan lebih tinggi dibandingkan dengan perlakuan yang lainnya., Milk is a source of animal protein that contains complete and complex nutritional components. People with lactose intolerance cannot consume milk containing lactose because there is no lactase enzyme in their digestion system to hydrolyze lactose into glucose and galactose. Lactose intolerance consumers can consume lactose by first breaking down the lactose present in dairy products using the lactase enzyme. Enzyme immobilization by entrapment method using an alginate matrix and calcium salt is made to produce low-lactose milk, which is economical in the food industry. The aims of this study were (1) to examine the effect of different calcium salts and their concentrations on the characteristics of the lactase enzyme trapping Ca-alginate + Lactase bead and its impact on the quality of
Keyword: alginate, RSM, calcium Lactate, Calcium Chloride, Enzyme Immobilization

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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