Judul: Pengaruh Penambahan Enzim terhadap Kualitas Pasta Ubi Jalar Ungu (Ipomoea batatas L.)
Abstrak: Ubi jalar ungu merupakan salah satu komoditas yang umum ditemui dan memiliki banyak manfaat, sehingga berpotensi digunakan sebagai bahan baku produk pangan. Salah satu upaya peningkatan kualitas pasta ubi jalar ungu dilakukan melalui proses penambahan enzim. Penelitian ini bertujuan meningkatkan kualitas pasta ubi jalar ungu dengan metode hidrolisis enzimatis. Proses hidrolisis dilakukan dengan 3 perlakuan penambahan enzim yaitu enzim α-amilase (1 U/g) pada suhu 95°C, enzim selulase (1 U/g) dan konsorsium enzim secara simultan (1:1 U/g) pada suhu 60°C. Pengaruh penambahan enzim terhadap kualitas pasta ubi jalar ungu diamati pada parameter viskositas, gula total, gula pereduksi, derajat polimerisasi, antosianin dan antioksidan. Hasil analisis statistik menunjukkan bahwa penambahan enzim berpengaruh signifikan terhadap karakteristik pasta ubi jalar ungu (α=5%). Berdasarkan hasil analisis, penambahan konsorsium enzim secara simultan menghasilkan pasta ubi jalar ungu dengan karakteristik fisikokimia terbaik yaitu dengan kadar gula total 91,97 (%) (b.k), gula pereduksi 17,19 (%) (b.k), derajat polimerisasi 5,35 (%), antosinain 184,4 (mg/100g) dan nilai IC50 5,52 (ppm). Perlakuan ini memberikan hasil terbaik dikarenakan enzim bekerja spesifik dengan mendegradasi polisakarida menjadi sakarida dengan rantai yang lebih pendek sehingga meningkatan kandungan gula total dan menyebabkan antosianin yang terperangkap dalam vakoula sel terlepas sehingga kadar antosianin dan aktivitas antioksidan produk meningkat.
Keyword: antioksidan, antosianin, enzim, pasta ubi jalar ungu

Judul: Pengaruh Perlakuan Fisik Terhadap Kualitas Pasta Ubi Jalar Ungu (Ipomoea batatas L.).
Abstrak: Ubi jalar ungu merupakan sumber bahan pangan yang memiliki banyak manfaat namun belum dimanfaatkan secara optimal. Hal itu menyebabkan ubi jalar berpotensi untuk diolah lebih lanjut untuk ditingkatkan kualitas fungsionalnya. Perlakuan fisik merupakan salah satu cara untuk meningkatkan kualitas pasta ubi jalar. Pemanasan dapat menyebabkan gelatinisasi dan terjadinya pelunakan jaringan daging ubi jalar ungu dan menginaktivasi polifenol oksidase dan peroksidase sehingga kerusakan enzimatis antosianin selama ekstraksi dapat ditekan. Penelitian ini bertujuan untuk meningkatkan kualitas pasta ubi ungu dengan perlakuan fisik. Perlakuan yang digunakan dalam penelitian ini adalah pengukusan (suhu 100oC selama 15 menit), microwave (power level 100% selama 3 menit), dan Heat Moisture Treatment (HMT) (suhu 121oC selama 1 jam dengan tiga kali siklus). Berdasarkan hasil analisis, pasta ubi kukus memiliki kadar antosianin tertinggi yaitu 156,10 mg/100g dan nilai IC50 yang dihasilkan sebesar 5,95 ppm, nilai viskositas 9150 cP dan total gula 69,5%. Pasta ubi jalar ungu dengan perlakuan microwave memiliki nilai viskositas (15300 cP), total gula (72,63%) dan gula pereduksi (8,06%) tertinggi. Pada modifikasi pasta ubi jalar ungu HMT diperoleh viskositas (6500 cP) dan total gula (59,83%) terendah dengan kadar antosianin (81,19 mg/100g) dan aktivitas antioksidan (IC50 9,01 ppm) lebih tinggi dari pasta ubi jalar ungu microwave. Kata kunci : heat moisture treatment, microwave, pengukusan , ubi jalar ungu
Keyword: heat moisture treatment, microwave, purple sweet potato, steaming

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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