Judul: Pengaruh sitokinin CPPU dan CoSO4 terhadap kesegaran sepal dan mutu manggis (Garcinia mangostana L.) pada penyimpanan suhu dingin
Abstrak: Manggis (Garcinia mangostana L.) merupakan salah satu komoditas dari sepuluh komoditas hortikultura prioritas nasional. Jumlah buah manggis yang sudah mampu diekspor hanya merupakan sebagian kecil dari produksi manggis Indonesia. Kendala yang dihadapi adalah penurunan mutu penampakan buah dan rendahnya shelf life buah manggis yang ditunjukkan dengan kulit buah manggis segera mengeras dan berubah warna menjadi ungu tua kehitaman, dan sepal buah segera berubah menjadi coklat pada beberapa hari setelah panen. Penelitian ini dilakukan untuk mengetahui pengaruh CPPU dan CoSO4 sehingga bisa mempertahankan kesegaran dan menghambat pengerasan kulit buah manggis selama penyimpanan pada suhu dingin (15oC). Penelitian ini dilaksanakan pada bulan Februari hingga Maret 2010 di Laboratorium Produksi Tanaman (Postharvest Laboaratory) Departemen Agronomi dan Hortikultura IPB. Rancangan yang digunakan dalam penelitian ini adalah Rancangan Kelompok Lengkap Teracak (RKLT) dua faktor yaitu faktor pemberian CPPU dan CoSO4. Faktor perlakuan pemberian CPPU terdiri dari empat taraf konsentrasi yaitu 0 ppm (Z0), 10 ppm (Z1), 20 ppm (Z2), 30 ppm (Z3). Perlakuan CoSO4 terdiri dari empat taraf konsentrasi yaitu 0 ppm (P0), 500 ppm (P1), 1000 ppm (P2), 2000 ppm (P3). Buah manggis disortasi dengan indeks kematangan yang seragam. Kemudian buah dicuci dengan sabun cair dan dibilas dengan air bersih. Buah direndam dalam larutan TBZ 1 ppm selama 30 detik. Tahap selanjutnya adalah perlakuan buah, buah manggis direndam pada larutan CPPU yang ditambah tween-20 1%. Setelah itu, buah kembali direndam dengan larutan CoSO4 yang ditambah dengan tween-20 1%. Buah kemudian disimpan pada cold storage dengan suhu 15oC. iii Pengamatan dilakukan selama penyimpanan yang meliputi pengamatan mutu fisik, mutu kimia, dan uji hedonik. Setiap parameter pengamatan diamati dengan interval pengamatan 2 hari sekali, dimulai dari hari ke-0 sampai dengan hari ke-30 setelah perlakuan. Pengamatan mutu fisik terdiri atas: (1) kesegaran sepal buah, (2) resistensi kulit buah (kemudahan untuk dibuka), (3) susut bobot buah, (4) kadar air kulit buah, dan (5) warna kulit dan sepal buah. Pengamatan mutu kimia terdiri atas padatan terlarut total (PTT) dan total asam tertitrasi (TAT). Uji hedonik dilakukan terhadap penampilan warna dan kesegaran sepal serta kulit buah.
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Judul: Pengaruh CPPU dan CoSO4 terhadap kualitas pascapanen buah manggis (Garcinia mangostana L.) selama penyimpanan
Abstrak: Mangosteen (Garcinia mangostana L.) fruit is one of the most delicious tropical fruits, known as “queen of tropical fruit” with short shelf life during storage. The research objective was to study the effects of CPPU and CoSO4 on postharvest quality and physiological changes of mangosteen fruit during storage. The experimental design was arranged in a completely randomized block design (CRBD) with two factors, i.e., cobalt sulphate and CPPU. Postharvest treatment with CPPU was found to be effective to promote lightness of mangosteen fruit at day 4 and day 6, while CoSO4 tended to accelerate the darkening in both fruit and sepal. The resistance of mangosteen fruit pericarp was considered as low (less than 2 kgf/cm2), representing that fruit were still easily to be opened during 30 days of storage. CPPU and CoSO4 were less effective in inhibiting fruit hardening. Titratable acidity was significantly reduced in CPPU-treated fruit at the end of storage, while total soluble solids were not clearly affected by the treatment. TSS/TA ratio was significantly higher in fruit treated with CPPU at the end of storage. Respiration rate of mangosteen fruit was low and remained constant with prolonged storage period. CPPU and/or CoSO4 could considerably decrease the respiration rate, but less effective in inhibiting ethylene production during storage at 14oC-16oC (78%-96% RH).
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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